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* Merge tag 'tty-4.1-rc1' of ↵Linus Torvalds2015-04-211-35/+18
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty/serial updates from Greg KH: "Here's the big tty/serial driver update for 4.1-rc1. It was delayed for a bit due to some questions surrounding some of the console command line parsing changes that are in here. There's still one tiny regression for people who were previously putting multiple console command lines and expecting them all to be ignored for some odd reason, but Peter is working on fixing that. If not, I'll send a revert for the offending patch, but I have faith that Peter can address it. Other than the console work here, there's the usual serial driver updates and changes, and a buch of 8250 reworks to try to make that driver easier to maintain over time, and have it support more devices in the future. All of these have been in linux-next for a while" * tag 'tty-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (119 commits) n_gsm: Drop unneeded cast on netdev_priv sc16is7xx: expose RTS inversion in RS-485 mode serial: 8250_pci: port failed after wakeup from S3 earlycon: 8250: Document kernel command line options earlycon: 8250: Fix command line regression earlycon: Fix __earlycon_table stride tty: clean up the tty time logic a bit serial: 8250_dw: only get the clock rate in one place serial: 8250_dw: remove useless ACPI ID check dmaengine: hsu: move memory allocation to GFP_NOWAIT dmaengine: hsu: remove redundant pieces of code serial: 8250_pci: add Intel Tangier support dmaengine: hsu: add Intel Tangier PCI ID serial: 8250_pci: replace switch-case by formula for Intel MID serial: 8250_pci: replace switch-case by formula tty: cpm_uart: replace CONFIG_8xx by CONFIG_CPM1 serial: jsm: some off by one bugs serial: xuartps: Fix check in console_setup(). serial: xuartps: Get rid of register access macros. serial: xuartps: Fix iobase use. ...
| * console: Add extensible console matchingPeter Hurley2015-03-261-34/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add match() method to struct console which allows the console to perform console command line matching instead of (or in addition to) default console matching (ie., by fixed name and index). The match() method returns 0 to indicate a successful match; normal console matching occurs if no match() method is defined or the match() method returns non-zero. The match() method is expected to set the console index if required. Re-implement earlycon-to-console-handoff with direct matching of "console=uart|uart8250,..." to the 8250 ttyS console. Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * Merge 4.0-rc3 into tty-testingGreg Kroah-Hartman2015-03-091-1/+0
| |\ | | | | | | | | | | | | | | | This resolves a merge issue in drivers/tty/serial/8250/8250_pci.c Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| | * console: Preserve index after console setup()Peter Hurley2015-03-071-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Before register_console() calls the setup() method of the matched console, the registering console index is already equal to the index from the console command line; ie. newcon->index == c->index. This change is also required to support extensible console matching; (the command line index may have no relation to the console index assigned by the console-defined match() function). Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | | Merge branch 'iocb' into for-nextAl Viro2015-04-121-2/+2
|\ \ \ | |/ / |/| |
| * | fs: move struct kiocb to fs.hChristoph Hellwig2015-03-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | struct kiocb now is a generic I/O container, so move it to fs.h. Also do a #include diet for aio.h while we're at it. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * | fs: remove ki_nbytesChristoph Hellwig2015-03-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | There is no need to pass the total request length in the kiocb, as we already get passed in through the iov_iter argument. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | | console: Fix console name size mismatchPeter Hurley2015-03-072-1/+2
| |/ |/| | | | | | | | | | | | | | | | | | | | | commit 6ae9200f2cab7 ("enlarge console.name") increased the storage for the console name to 16 bytes, but not the corresponding struct console_cmdline::name storage. Console names longer than 8 bytes cause read beyond end-of-string and failure to match console; I'm not sure if there are other unexpected consequences. Cc: <stable@vger.kernel.org> # 2.6.22+ Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* | Merge tag 'for_linux-3.20-rc1' of ↵Linus Torvalds2015-02-211-1/+1
|\ \ | |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb Pull kgdb/kdb updates from Jason Wessel: "KGDB/KDB New: - KDB: improved searching - No longer enter debug core on panic if panic timeout is set KGDB/KDB regressions / cleanups - fix pdf doc build errors - prevent junk characters on kdb console from printk levels" * tag 'for_linux-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb: kgdb, docs: Fix <para> pdfdocs build errors debug: prevent entering debug mode on panic/exception. kdb: Const qualifier for kdb_getstr's prompt argument kdb: Provide forward search at more prompt kdb: Fix a prompt management bug when using | grep kdb: Remove stack dump when entering kgdb due to NMI kdb: Avoid printing KERN_ levels to consoles kdb: Fix off by one error in kdb_cpu() kdb: fix incorrect counts in KDB summary command output
| * kdb: Avoid printing KERN_ levels to consolesDaniel Thompson2015-02-191-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently when kdb traps printk messages then the raw log level prefix (consisting of '\001' followed by a numeral) does not get stripped off before the message is issued to the various I/O handlers supported by kdb. This causes annoying visual noise as well as causing problems grepping for ^. It is also a change of behaviour compared to normal usage of printk() usage. For example <SysRq>-h ends up with different output to that of kdb's "sr h". This patch addresses the problem by stripping log levels from messages before they are issued to the I/O handlers. printk() which can also act as an i/o handler in some cases is special cased; if the caller provided a log level then the prefix will be preserved when sent to printk(). The addition of non-printable characters to the output of kdb commands is a regression, albeit and extremely elderly one, introduced by commit 04d2c8c83d0e ("printk: convert the format for KERN_<LEVEL> to a 2 byte pattern"). Note also that this patch does *not* restore the original behaviour from v3.5. Instead it makes printk() from within a kdb command display the message without any prefix (i.e. like printk() normally does). Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Joe Perches <joe@perches.com> Cc: stable@vger.kernel.org Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | printk: correct timeout comment, neaten MODULE_PARM_DESCJoe Perches2015-02-131-6/+6
|/ | | | | | | | | Neaten the MODULE_PARAM_DESC message. Use 30 seconds in the comment for the zap console locks timeout. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge tag 'trace-seq-buf-3.19-v2' of ↵Linus Torvalds2014-12-131-2/+8
|\ | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fixlet from Steven Rostedt: "Remove unnecessary preempt_disable in printk()" * tag 'trace-seq-buf-3.19-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: printk: Do not disable preemption for accessing printk_func
| * printk: Do not disable preemption for accessing printk_funcSteven Rostedt (Red Hat)2014-12-111-2/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | As printk_func will either be the default function, or a per_cpu function for the current CPU, there's no reason to disable preemption to access it from printk. That's because if the printk_func is not the default then the caller had better disabled preemption as they were the one to change it. Link: http://lkml.kernel.org/r/CA+55aFz5-_LKW4JHEBoWinN9_ouNcGRWAF2FUA35u46FRN-Kxw@mail.gmail.com Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* | Merge tag 'trace-seq-buf-3.19' of ↵Linus Torvalds2014-12-111-9/+32
|\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull nmi-safe seq_buf printk update from Steven Rostedt: "This code is a fork from the trace-3.19 pull as it needed the trace_seq clean ups from that branch. This code solves the issue of performing stack dumps from NMI context. The issue is that printk() is not safe from NMI context as if the NMI were to trigger when a printk() was being performed, the NMI could deadlock from the printk() internal locks. This has been seen in practice. With lots of review from Petr Mladek, this code went through several iterations, and we feel that it is now at a point of quality to be accepted into mainline. Here's what is contained in this patch set: - Creates a "seq_buf" generic buffer utility that allows a descriptor to be passed around where functions can write their own "printk()" formatted strings into it. The generic version was pulled out of the trace_seq() code that was made specifically for tracing. - The seq_buf code was change to model the seq_file code. I have a patch (not included for 3.19) that converts the seq_file.c code over to use seq_buf.c like the trace_seq.c code does. This was done to make sure that seq_buf.c is compatible with seq_file.c. I may try to get that patch in for 3.20. - The seq_buf.c file was moved to lib/ to remove it from being dependent on CONFIG_TRACING. - The printk() was updated to allow for a per_cpu "override" of the internal calls. That is, instead of writing to the console, a call to printk() may do something else. This made it easier to allow the NMI to change what printk() does in order to call dump_stack() without needing to update that code as well. - Finally, the dump_stack from all CPUs via NMI code was converted to use the seq_buf code. The caller to trigger the NMI code would wait till all the NMIs finished, and then it would print the seq_buf data to the console safely from a non NMI context One added bonus is that this code also makes the NMI dump stack work on PREEMPT_RT kernels. As printk() includes sleeping locks on PREEMPT_RT, printk() only writes to console if the console does not use any rt_mutex converted spin locks. Which a lot do" * tag 'trace-seq-buf-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: x86/nmi: Fix use of unallocated cpumask_var_t printk/percpu: Define printk_func when printk is not defined x86/nmi: Perform a safe NMI stack trace on all CPUs printk: Add per_cpu printk func to allow printk to be diverted seq_buf: Move the seq_buf code to lib/ seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions tracing: Have seq_buf use full buffer seq_buf: Add seq_buf_can_fit() helper function tracing: Add paranoid size check in trace_printk_seq() tracing: Use trace_seq_used() and seq_buf_used() instead of len tracing: Clean up tracing_fill_pipe_page() seq_buf: Create seq_buf_used() to find out how much was written tracing: Add a seq_buf_clear() helper and clear len and readpos in init tracing: Convert seq_buf fields to be like seq_file fields tracing: Convert seq_buf_path() to be like seq_path() tracing: Create seq_buf layer in trace_seq
| * printk/percpu: Define printk_func when printk is not definedSteven Rostedt (Red Hat)2014-11-211-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To avoid include hell, the per_cpu variable printk_func was declared in percpu.h. But it is only defined if printk is defined. As users of printk may also use the printk_func variable, it needs to be defined even if CONFIG_PRINTK is not. Also add a printk.h include in percpu.h just to be safe. Link: http://lkml.kernel.org/r/20141121183215.01ba539c@canb.auug.org.au Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * printk: Add per_cpu printk func to allow printk to be divertedSteven Rostedt (Red Hat)2014-11-201-9/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Being able to divert printk to call another function besides the normal logging is useful for such things like NMI handling. If some functions are to be called from NMI that does printk() it is possible to lock up the box if the nmi handler triggers when another printk is happening. One example of this use is to perform a stack trace on all CPUs via NMI. But if the NMI is to do the printk() it can cause the system to lock up. By allowing the printk to be diverted to another function that can safely record the printk output and then print it when it in a safe context then NMIs will be safe to call these functions like show_regs(). Link: http://lkml.kernel.org/p/20140619213952.209176403@goodmis.org Tested-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Petr Mladek <pmladek@suse.cz> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* | Merge branch 'akpm' (patchbomb from Andrew)Linus Torvalds2014-12-111-27/+22
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge first patchbomb from Andrew Morton: - a few minor cifs fixes - dma-debug upadtes - ocfs2 - slab - about half of MM - procfs - kernel/exit.c - panic.c tweaks - printk upates - lib/ updates - checkpatch updates - fs/binfmt updates - the drivers/rtc tree - nilfs - kmod fixes - more kernel/exit.c - various other misc tweaks and fixes * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (190 commits) exit: pidns: fix/update the comments in zap_pid_ns_processes() exit: pidns: alloc_pid() leaks pid_namespace if child_reaper is exiting exit: exit_notify: re-use "dead" list to autoreap current exit: reparent: call forget_original_parent() under tasklist_lock exit: reparent: avoid find_new_reaper() if no children exit: reparent: introduce find_alive_thread() exit: reparent: introduce find_child_reaper() exit: reparent: document the ->has_child_subreaper checks exit: reparent: s/while_each_thread/for_each_thread/ in find_new_reaper() exit: reparent: fix the cross-namespace PR_SET_CHILD_SUBREAPER reparenting exit: reparent: fix the dead-parent PR_SET_CHILD_SUBREAPER reparenting exit: proc: don't try to flush /proc/tgid/task/tgid exit: release_task: fix the comment about group leader accounting exit: wait: drop tasklist_lock before psig->c* accounting exit: wait: don't use zombie->real_parent exit: wait: cleanup the ptrace_reparented() checks usermodehelper: kill the kmod_thread_locker logic usermodehelper: don't use CLONE_VFORK for ____call_usermodehelper() fs/hfs/catalog.c: fix comparison bug in hfs_cat_keycmp nilfs2: fix the nilfs_iget() vs. nilfs_new_inode() races ...
| * | printk: drop logbuf_cpu volatile qualifierAlex Elder2014-12-111-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pranith Kumar posted a patch in which removed the "volatile" qualifier for the "logbuf_cpu" variable in vprintk_emit(). https://lkml.org/lkml/2014/11/13/894 In his patch, he used ACCESS_ONCE() for all references to that symbol to provide whatever protection was intended. There was some discussion that followed, and in the end Steven Rostedt concluded that not only was "volatile" not needed, neither was it required to use ACCESS_ONCE(). I offered an elaborate description that concluded Steven was right, and Pranith asked me to submit an alternative patch. And this is it. The basic reason "volatile" is not needed is that "logbuf_cpu" has static storage duration, and vprintk_emit() is an exported interface. This means that the value of logbuf_cpu must be read from memory the first time it is used in a particular call of vprintk_emit(). The variable's value is read only once in that function, when it's read it'll be the copy from memory (or cache). In addition, the value of "logbuf_cpu" is only ever written under protection of a spinlock. So the value that is read is the "real" value (and not an out-of-date cached one). If its value is not UINT_MAX, it is the current CPU's processor id, and it will have been last written by the running CPU. Signed-off-by: Alex Elder <elder@linaro.org> Reported-by: Pranith Kumar <bobby.prani@gmail.com> Suggested-by: Steven Rostedt <rostedt@goodmis.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Petr Mladek <pmladek@suse.cz> Cc: Luis R. Rodriguez <mcgrof@suse.com> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * | printk: add and use LOGLEVEL_<level> defines for KERN_<LEVEL> equivalentsJoe Perches2014-12-111-15/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use #defines instead of magic values. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jason Baron <jbaron@akamai.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * | printk: remove used-once early_vprintkJoe Perches2014-12-111-11/+8
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Eliminate the unlikely possibility of message interleaving for early_printk/early_vprintk use. early_vprintk can be done via the %pV extension so remove this unnecessary function and change early_printk to have the equivalent vprintk code. All uses of early_printk already end with a newline so also remove the unnecessary newline from the early_printk function. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Chris Metcalf <cmetcalf@tilera.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* / pstore: Honor dmesg_restrict sysctl on dmesg dumpsSebastian Schmidt2014-11-051-1/+1
|/ | | | | | | | | | | | | | | | When the kernel.dmesg_restrict restriction is in place, only users with CAP_SYSLOG should be able to access crash dumps (like: attacker is trying to exploit a bug, watchdog reboots, attacker can happily read crash dumps and logs). This puts the restriction on console-* types as well as sensitive information could have been leaked there. Other log types are unaffected. Signed-off-by: Sebastian Schmidt <yath@yath.de> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Tony Luck <tony.luck@intel.com>
* Merge branch 'for-3.18-consistent-ops' of ↵Linus Torvalds2014-10-151-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu Pull percpu consistent-ops changes from Tejun Heo: "Way back, before the current percpu allocator was implemented, static and dynamic percpu memory areas were allocated and handled separately and had their own accessors. The distinction has been gone for many years now; however, the now duplicate two sets of accessors remained with the pointer based ones - this_cpu_*() - evolving various other operations over time. During the process, we also accumulated other inconsistent operations. This pull request contains Christoph's patches to clean up the duplicate accessor situation. __get_cpu_var() uses are replaced with with this_cpu_ptr() and __this_cpu_ptr() with raw_cpu_ptr(). Unfortunately, the former sometimes is tricky thanks to C being a bit messy with the distinction between lvalues and pointers, which led to a rather ugly solution for cpumask_var_t involving the introduction of this_cpu_cpumask_var_ptr(). This converts most of the uses but not all. Christoph will follow up with the remaining conversions in this merge window and hopefully remove the obsolete accessors" * 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (38 commits) irqchip: Properly fetch the per cpu offset percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t -fix ia64: sn_nodepda cannot be assigned to after this_cpu conversion. Use __this_cpu_write. percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t Revert "powerpc: Replace __get_cpu_var uses" percpu: Remove __this_cpu_ptr clocksource: Replace __this_cpu_ptr with raw_cpu_ptr sparc: Replace __get_cpu_var uses avr32: Replace __get_cpu_var with __this_cpu_write blackfin: Replace __get_cpu_var uses tile: Use this_cpu_ptr() for hardware counters tile: Replace __get_cpu_var uses powerpc: Replace __get_cpu_var uses alpha: Replace __get_cpu_var ia64: Replace __get_cpu_var uses s390: cio driver &__get_cpu_var replacements s390: Replace __get_cpu_var uses mips: Replace __get_cpu_var uses MIPS: Replace __get_cpu_var uses in FPU emulator. arm: Replace __this_cpu_ptr with raw_cpu_ptr ...
| * kernel misc: Replace __get_cpu_var usesChristoph Lameter2014-08-261-2/+2
| | | | | | | | | | | | | | | | Replace uses of __get_cpu_var for address calculation with this_cpu_ptr. Cc: akpm@linux-foundation.org Signed-off-by: Christoph Lameter <cl@linux.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | printk: git rid of [sched_delayed] message for printk_deferredMarkus Trippelsdorf2014-10-141-6/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 458df9fd4815 ("printk: remove separate printk_sched buffers and use printk buf instead") hardcodes printk_deferred() to KERN_WARNING and inserts the string "[sched_delayed] " before the actual message. However it doesn't take into account the KERN_* prefix of the message, that now ends up in the middle of the output: [sched_delayed] ^a4CE: hpet increased min_delta_ns to 20115 nsec Fix this by just getting rid of the "[sched_delayed] " scnprintf(). The prefix is useless since 458df9fd4815 anyway since from that moment printk_deferred() inserts the message into the kernel printk buffer immediately. So if the message eventually gets printed to console, it is printed in the correct order with other messages and there's no need for any special prefix. And if the kernel crashes before the message makes it to console, then prefix in the printk buffer doesn't make the situation any better. Link: http://lkml.org/lkml/2014/9/14/4 Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de> Acked-by: Jan Kara <jack@suse.cz> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | printk: don't bother using LOG_CPU_MAX_BUF_SHIFT on !SMPGeert Uytterhoeven2014-10-141-1/+6
| | | | | | | | | | | | | | | | | | | | | | When configuring a uniprocessor kernel, don't bother the user with an irrelevant LOG_CPU_MAX_BUF_SHIFT question, and don't build the unused code. Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Luis R. Rodriguez <mcgrof@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | switch /dev/kmsg to ->write_iter()Al Viro2014-10-091-13/+7
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | kernel/printk/printk.c: fix faulty logic in the case of recursive printkPatrick Palka2014-09-111-3/+3
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We shouldn't set text_len in the code path that detects printk recursion because text_len corresponds to the length of the string inside textbuf. A few lines down from the line text_len = strlen(recursion_msg); is the line text_len += vscnprintf(text + text_len, ...); So if printk detects recursion, it sets text_len to 29 (the length of recursion_msg) and logs an error. Then the message supplied by the caller of printk is stored inside textbuf but offset by 29 bytes. This means that the output of the recursive call to printk will contain 29 bytes of garbage in front of it. This defect is caused by commit 458df9fd4815 ("printk: remove separate printk_sched buffers and use printk buf instead") which turned the line text_len = vscnprintf(text, ...); into text_len += vscnprintf(text + text_len, ...); To fix this, this patch avoids setting text_len when logging the printk recursion error. This patch also marks unlikely() the branch leading up to this code. Fixes: 458df9fd4815b478 ("printk: remove separate printk_sched buffers and use printk buf instead") Signed-off-by: Patrick Palka <patrick@parcs.ath.cx> Reviewed-by: Petr Mladek <pmladek@suse.cz> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: Add function to return log buffer address and sizeVasant Hegde2014-08-131-0/+12
| | | | | | | | | | | | | | | | | Platforms like IBM Power Systems supports service processor assisted dump. It provides interface to add memory region to be captured when system is crashed. During initialization/running we can add kernel memory region to be collected. Presently we don't have a way to get the log buffer base address and size. This patch adds support to return log buffer address and size. Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: Andrew Morton <akpm@linux-foundation.org>
* kernel/printk/printk.c: fix bool assignementsNeil Zhang2014-08-071-3/+3
| | | | | | | | Fix coccinelle warnings. Signed-off-by: Neil Zhang <zhangwm@marvell.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: enable interrupts before calling console_trylock_for_printk()Jan Kara2014-08-071-10/+21
| | | | | | | | | | | | | | | | | | | | | | | | | We need interrupts disabled when calling console_trylock_for_printk() only so that cpu id we pass to can_use_console() remains valid (for other things console_sem provides all the exclusion we need and deadlocks on console_sem due to interrupts are impossible because we use down_trylock()). However if we are rescheduled, we are guaranteed to run on an online cpu so we can easily just get the cpu id in can_use_console(). We can lose a bit of performance when we enable interrupts in vprintk_emit() and then disable them again in console_unlock() but OTOH it can somewhat reduce interrupt latency caused by console_unlock(). We differ from (reverted) commit 939f04bec1a4 in that we avoid calling console_unlock() from vprintk_emit() with lockdep enabled as that has unveiled quite some bugs leading to system freezes during boot (e.g. https://lkml.org/lkml/2014/5/30/242, https://lkml.org/lkml/2014/6/28/521). Signed-off-by: Jan Kara <jack@suse.cz> Tested-by: Andreas Bombe <aeb@debian.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: miscellaneous cleanupsAlex Elder2014-08-071-13/+13
| | | | | | | | | | | | | | | | | | | | | | | | Some small cleanups to kernel/printk/printk.c. None of them should cause any change in behavior. - When CONFIG_PRINTK is defined, parenthesize the value of LOG_LINE_MAX. - When CONFIG_PRINTK is *not* defined, there is an extra LOG_LINE_MAX definition; delete it. - Pull an assignment out of a conditional expression in console_setup(). - Use isdigit() in console_setup() rather than open coding it. - In update_console_cmdline(), drop a NUL-termination assignment; the strlcpy() call that precedes it guarantees it's not needed. - Simplify some logic in printk_timed_ratelimit(). Signed-off-by: Alex Elder <elder@linaro.org> Reviewed-by: Petr Mladek <pmladek@suse.cz> Cc: Andi Kleen <ak@linux.intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: Jan Kara <jack@suse.cz> Cc: John Stultz <john.stultz@linaro.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: use a clever macroAlex Elder2014-08-071-10/+2
| | | | | | | | | | | | | | | Use the IS_ENABLED() macro rather than #ifdef blocks to set certain global values. Signed-off-by: Alex Elder <elder@linaro.org> Acked-by: Borislav Petkov <bp@suse.de> Reviewed-by: Petr Mladek <pmladek@suse.cz> Cc: Andi Kleen <ak@linux.intel.com> Cc: Jan Kara <jack@suse.cz> Cc: John Stultz <john.stultz@linaro.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: fix some commentsAlex Elder2014-08-071-11/+12
| | | | | | | | | | | | | | | Fix a few comments that don't accurately describe their corresponding code. It also fixes some minor typographical errors. Signed-off-by: Alex Elder <elder@linaro.org> Reviewed-by: Petr Mladek <pmladek@suse.cz> Cc: Andi Kleen <ak@linux.intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: Jan Kara <jack@suse.cz> Cc: John Stultz <john.stultz@linaro.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: rename DEFAULT_MESSAGE_LOGLEVELAlex Elder2014-08-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | Commit a8fe19ebfbfd ("kernel/printk: use symbolic defines for console loglevels") makes consistent use of symbolic values for printk() log levels. The naming scheme used is different from the one used for DEFAULT_MESSAGE_LOGLEVEL though. Change that symbol name to be MESSAGE_LOGLEVEL_DEFAULT for consistency. And because the value of that symbol comes from a similarly-named config option, rename CONFIG_DEFAULT_MESSAGE_LOGLEVEL as well. Signed-off-by: Alex Elder <elder@linaro.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Borislav Petkov <bp@suse.de> Cc: Jan Kara <jack@suse.cz> Cc: John Stultz <john.stultz@linaro.org> Cc: Petr Mladek <pmladek@suse.cz> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: tweak do_syslog() to match commentsAlex Elder2014-08-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | In do_syslog() there's a path used by kmsg_poll() and kmsg_read() that only needs to know whether there's any data available to read (and not its size). These callers only check for non-zero return. As a shortcut, do_syslog() returns the difference between what has been logged and what has been "seen." The comments say that the "count of records" should be returned but it's not. Instead it returns (log_next_idx - syslog_idx), which is a difference between buffer offsets--and the result could be negative. The behavior is the same (it'll be zero or not in the same cases), but the count of records is more meaningful and it matches what the comments say. So change the code to return that. Signed-off-by: Alex Elder <elder@linaro.org> Cc: Petr Mladek <pmladek@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Joe Perches <joe@perches.com> Cc: John Stultz <john.stultz@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: allow increasing the ring buffer depending on the number of CPUsLuis R. Rodriguez2014-08-071-0/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The default size of the ring buffer is too small for machines with a large amount of CPUs under heavy load. What ends up happening when debugging is the ring buffer overlaps and chews up old messages making debugging impossible unless the size is passed as a kernel parameter. An idle system upon boot up will on average spew out only about one or two extra lines but where this really matters is on heavy load and that will vary widely depending on the system and environment. There are mechanisms to help increase the kernel ring buffer for tracing through debugfs, and those interfaces even allow growing the kernel ring buffer per CPU. We also have a static value which can be passed upon boot. Relying on debugfs however is not ideal for production, and relying on the value passed upon bootup is can only used *after* an issue has creeped up. Instead of being reactive this adds a proactive measure which lets you scale the amount of contributions you'd expect to the kernel ring buffer under load by each CPU in the worst case scenario. We use num_possible_cpus() to avoid complexities which could be introduced by dynamically changing the ring buffer size at run time, num_possible_cpus() lets us use the upper limit on possible number of CPUs therefore avoiding having to deal with hotplugging CPUs on and off. This introduces the kernel configuration option LOG_CPU_MAX_BUF_SHIFT which is used to specify the maximum amount of contributions to the kernel ring buffer in the worst case before the kernel ring buffer flips over, the size is specified as a power of 2. The total amount of contributions made by each CPU must be greater than half of the default kernel ring buffer size (1 << LOG_BUF_SHIFT bytes) in order to trigger an increase upon bootup. The kernel ring buffer is increased to the next power of two that would fit the required minimum kernel ring buffer size plus the additional CPU contribution. For example if LOG_BUF_SHIFT is 18 (256 KB) you'd require at least 128 KB contributions by other CPUs in order to trigger an increase of the kernel ring buffer. With a LOG_CPU_BUF_SHIFT of 12 (4 KB) you'd require at least anything over > 64 possible CPUs to trigger an increase. If you had 128 possible CPUs the amount of minimum required kernel ring buffer bumps to: ((1 << 18) + ((128 - 1) * (1 << 12))) / 1024 = 764 KB Since we require the ring buffer to be a power of two the new required size would be 1024 KB. This CPU contributions are ignored when the "log_buf_len" kernel parameter is used as it forces the exact size of the ring buffer to an expected power of two value. [pmladek@suse.cz: fix build] Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.cz> Tested-by: Davidlohr Bueso <davidlohr@hp.com> Tested-by: Petr Mladek <pmladek@suse.cz> Reviewed-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Andrew Lunn <andrew@lunn.ch> Cc: Stephen Warren <swarren@wwwdotorg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Petr Mladek <pmladek@suse.cz> Cc: Joe Perches <joe@perches.com> Cc: Arun KS <arunks.linux@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: make dynamic units clear for the kernel ring bufferLuis R. Rodriguez2014-08-071-1/+1
| | | | | | | | | | | | | | | | | | Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Suggested-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Andrew Lunn <andrew@lunn.ch> Cc: Stephen Warren <swarren@wwwdotorg.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Petr Mladek <pmladek@suse.cz> Cc: Joe Perches <joe@perches.com> Cc: Arun KS <arunks.linux@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: move power of 2 practice of ring buffer size to a helperLuis R. Rodriguez2014-08-071-4/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In practice the power of 2 practice of the size of the kernel ring buffer remains purely historical but not a requirement, specially now that we have LOG_ALIGN and use it for both static and dynamic allocations. It could have helped with implicit alignment back in the days given the even the dynamically sized ring buffer was guaranteed to be aligned so long as CONFIG_LOG_BUF_SHIFT was set to produce a __LOG_BUF_LEN which is architecture aligned, since log_buf_len=n would be allowed only if it was > __LOG_BUF_LEN and we always ended up rounding the log_buf_len=n to the next power of 2 with roundup_pow_of_two(), any multiple of 2 then should be also architecture aligned. These assumptions of course relied heavily on CONFIG_LOG_BUF_SHIFT producing an aligned value but users can always change this. We now have precise alignment requirements set for the log buffer size for both static and dynamic allocations, but lets upkeep the old practice of using powers of 2 for its size to help with easy expected scalable values and the allocators for dynamic allocations. We'll reuse this later so move this into a helper. Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Cc: Andrew Lunn <andrew@lunn.ch> Cc: Stephen Warren <swarren@wwwdotorg.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Petr Mladek <pmladek@suse.cz> Cc: Joe Perches <joe@perches.com> Cc: Arun KS <arunks.linux@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: make dynamic kernel ring buffer alignment explicitLuis R. Rodriguez2014-08-071-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We have to consider alignment for the ring buffer both for the default static size, and then also for when an dynamic allocation is made when the log_buf_len=n kernel parameter is passed to set the size specifically to a size larger than the default size set by the architecture through CONFIG_LOG_BUF_SHIFT. The default static kernel ring buffer can be aligned properly if architectures set CONFIG_LOG_BUF_SHIFT properly, we provide ranges for the size though so even if CONFIG_LOG_BUF_SHIFT has a sensible aligned value it can be reduced to a non aligned value. Commit 6ebb017de9 ("printk: Fix alignment of buf causing crash on ARM EABI") by Andrew Lunn ensures the static buffer is always aligned and the decision of alignment is done by the compiler by using __alignof__(struct log). When log_buf_len=n is used we allocate the ring buffer dynamically. Dynamic allocation varies, for the early allocation called before setup_arch() memblock_virt_alloc() requests a page aligment and for the default kernel allocation memblock_virt_alloc_nopanic() requests no special alignment, which in turn ends up aligning the allocation to SMP_CACHE_BYTES, which is L1 cache aligned. Since we already have the required alignment for the kernel ring buffer though we can do better and request explicit alignment for LOG_ALIGN. This does that to be safe and make dynamic allocation alignment explicit. Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> Tested-by: Petr Mladek <pmladek@suse.cz> Acked-by: Petr Mladek <pmladek@suse.cz> Cc: Andrew Lunn <andrew@lunn.ch> Cc: Stephen Warren <swarren@wwwdotorg.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Petr Mladek <pmladek@suse.cz> Cc: Joe Perches <joe@perches.com> Cc: Arun KS <arunks.linux@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: Davidlohr Bueso <davidlohr@hp.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel/printk/printk.c: revert "printk: enable interrupts before calling ↵Andrew Morton2014-07-031-26/+18
| | | | | | | | | | | | | | | | | | | | | | | console_trylock_for_printk()" Revert commit 939f04bec1a4 ("printk: enable interrupts before calling console_trylock_for_printk()"). Andreas reported: : None of the post 3.15 kernel boot for me. They all hang at the GRUB : screen telling me it loaded and started the kernel, but the kernel : itself stops before it prints anything (or even replaces the GRUB : background graphics). 939f04bec1a4 is modest latency reduction. Revert it until we understand the reason for these failures. Reported-by: Andreas Bombe <aeb@debian.org> Cc: Jan Kara <jack@suse.cz> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel/printk: use symbolic defines for console loglevelsBorislav Petkov2014-06-051-10/+3
| | | | | | | | | | | | | | | | | | | | ... instead of naked numbers. Stuff in sysrq.c used to set it to 8 which is supposed to mean above default level so set it to DEBUG instead as we're terminating/killing all tasks and we want to be verbose there. Also, correct the check in x86_64_start_kernel which should be >= as we're clearly issuing the string there for all debug levels, not only the magical 10. Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> Cc: Joe Perches <joe@perches.com> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: report dropping of messages from logbufWill Deacon2014-06-051-2/+7
| | | | | | | | | | | | | | | | | | | | If the log ring buffer becomes full, we silently overwrite old messages with new data. console_unlock will detect this case and fast-forward the console_* pointers to skip over the corrupted data, but nothing will be reported to the user. This patch hijacks the first valid log message after detecting that we dropped messages and prefixes it with a note detailing how many messages were dropped. For long (~1000 char) messages, this will result in some truncation of the real message, but given that we're dropping things anyway, that doesn't seem to be the end of the world. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Kay Sievers <kay@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: rename printk_sched to printk_deferredJohn Stultz2014-06-051-1/+1
| | | | | | | | | | | | | | | | | | After learning we'll need some sort of deferred printk functionality in the timekeeping core, Peter suggested we rename the printk_sched function so it can be reused by needed subsystems. This only changes the function name. No logic changes. Signed-off-by: John Stultz <john.stultz@linaro.org> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Cc: Jan Kara <jack@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jiri Bohac <jbohac@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: disable preemption for printk_schedJohn Stultz2014-06-051-0/+2
| | | | | | | | | | | | | | | | | | An earlier change in -mm (printk: remove separate printk_sched buffers...), removed the printk_sched irqsave/restore lines since it was safe for current users. Since we may be expanding usage of printk_sched(), disable preepmtion for this function to make it more generally safe to call. Signed-off-by: John Stultz <john.stultz@linaro.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jiri Bohac <jbohac@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: remove separate printk_sched buffers and use printk buf insteadSteven Rostedt2014-06-051-18/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To prevent deadlocks with doing a printk inside the scheduler, printk_sched() was created. The issue is that printk has a console_sem that it can grab and release. The release does a wake up if there's a task pending on the sem, and this wake up grabs the rq locks that is held in the scheduler. This leads to a possible deadlock if the wake up uses the same rq as the one with the rq lock held already. What printk_sched() does is to save the printk write in a per cpu buffer and sets the PRINTK_PENDING_SCHED flag. On a timer tick, if this flag is set, the printk() is done against the buffer. There's a couple of issues with this approach. 1) If two printk_sched()s are called before the tick, the second one will overwrite the first one. 2) The temporary buffer is 512 bytes and is per cpu. This is a quite a bit of space wasted for something that is seldom used. In order to remove this, the printk_sched() can use the printk buffer instead, and delay the console_trylock()/console_unlock() to the queued work. Because printk_sched() would then be taking the logbuf_lock, the logbuf_lock must not be held while doing anything that may call into the scheduler functions, which includes wake ups. Unfortunately, printk() also has a console_sem that it uses, and on release, the up(&console_sem) may do a wake up of any pending waiters. This must be avoided while holding the logbuf_lock. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: enable interrupts before calling console_trylock_for_printk()Jan Kara2014-06-051-11/+18
| | | | | | | | | | | | | | | | | | | | We need interrupts disabled when calling console_trylock_for_printk() only so that cpu id we pass to can_use_console() remains valid (for other things console_sem provides all the exclusion we need and deadlocks on console_sem due to interrupts are impossible because we use down_trylock()). However if we are rescheduled, we are guaranteed to run on an online cpu so we can easily just get the cpu id in can_use_console(). We can lose a bit of performance when we enable interrupts in vprintk_emit() and then disable them again in console_unlock() but OTOH it can somewhat reduce interrupt latency caused by console_unlock() especially since later in the patch series we will want to spin on console_sem in console_trylock_for_printk(). Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: fix lockdep instrumentation of console_semJan Kara2014-06-051-14/+32
| | | | | | | | | | | | | | | | | | | Printk calls mutex_acquire() / mutex_release() by hand to instrument lockdep about console_sem. However in some corner cases the instrumentation is missing. Fix the problem by creating helper functions for locking / unlocking console_sem which take care of lockdep instrumentation as well. Signed-off-by: Jan Kara <jack@suse.cz> Reported-by: Fabio Estevam <festevam@gmail.com> Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Tested-by: Fabio Estevam <fabio.estevam@freescale.com> Tested-By: Valdis Kletnieks <valdis.kletnieks@vt.edu> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: release lockbuf_lock before calling console_trylock_for_printk()Jan Kara2014-06-051-33/+21
| | | | | | | | | | | | | | | | | | | | | | There's no reason to hold lockbuf_lock when entering console_trylock_for_printk(). The first thing this function does is to call down_trylock(console_sem) and if that fails it immediately unlocks lockbuf_lock. So lockbuf_lock isn't needed for that branch. When down_trylock() succeeds, the rest of console_trylock() is OK without lockbuf_lock (it is called without it from other places), and the only remaining thing in console_trylock_for_printk() is can_use_console() call. For that call console_sem is enough (it iterates all consoles and checks CON_ANYTIME flag). So we drop logbuf_lock before entering console_trylock_for_printk() which simplifies the code. [akpm@linux-foundation.org: fix have_callable_console() comment] Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: remove outdated commentJan Kara2014-06-051-2/+1
| | | | | | | | | | | | | | | | | | Comment about interesting interlocking between lockbuf_lock and console_sem is outdated. It was added in 2002 by commit a880f45a48be during conversion of console_lock to console_sem + lockbuf_lock. At that time release_console_sem() (today's equivalent is console_unlock()) was indeed using lockbuf_lock to avoid races between trylock on console_sem in printk() and unlock of console_sem. However these days the interlocking is gone and the races are avoided by rechecking logbuf state after releasing console_sem. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk: return really stored message lengthPetr Mladek2014-06-051-15/+21
| | | | | | | | | | | | | | | | | | | | | | I wonder if anyone uses printk return value but it is there and should be counted correctly. This patch modifies log_store() to return the number of really stored bytes from the 'text' part. Also it handles the return value in vprintk_emit(). Note that log_store() is used also in cont_flush() but we could ignore the return value there. The function works with characters that were already counted earlier. In addition, the store could newer fail here because the length of the printed text is limited by the "cont" buffer and "dict" is NULL. Signed-off-by: Petr Mladek <pmladek@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Kay Sievers <kay@vrfy.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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