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* PTR_ERR should be called before its argument is cleared.Julia Lawall2012-02-211-1/+4
| | | | | | | | | | | | | | | | | | | | | | The semantic match that finds this problem is as follows: (http://coccinelle.lip6.fr/) // <smpl> @@ expression e,e1; constant c; @@ *e = c ... when != e = e1 when != &e when != true IS_ERR(e) *PTR_ERR(e) // </smpl> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr> Reported-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Trace only after NULL-pointer checkPaul E. McKenney2012-02-211-2/+2
| | | | | | | Fix a bonehead error introduced when adding event tracing to rcutorture. Move the traces to follow the NULL-pointer checks. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Add CPU-stall capability to rcutorturePaul E. McKenney2012-02-211-0/+66
| | | | | | | | | | | | | Add module parameters to rcutorture that induce a CPU stall. The stall_cpu parameter specifies how long to stall in seconds, defaulting to zero, which indicates no stalling is to be undertaken. The stall_cpu_holdoff parameter specifies how many seconds after insmod (or boot, if rcutorture is built into the kernel) that this stall is to start. The default value for stall_cpu_holdoff is ten seconds. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcutorture: Permit holding off CPU-hotplug operations during bootPaul E. McKenney2012-02-211-2/+10
| | | | | | | | | | | When rcutorture is started automatically at boot time, it might well also start CPU-hotplug operations at that time, which might not be desirable. This commit therefore adds an rcutorture parameter that allows CPU-hotplug operations to be held off for the specified number of seconds after the start of boot. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Make rcutorture flag online/offline failuresPaul E. McKenney2012-02-211-0/+4
| | | | | | | | Make rcutorture check for CPU-hotplug failures and complain if there were any. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Add missing __cpuinit annotation in rcutorture codeHeiko Carstens2012-01-161-2/+2
| | | | | | | | | | | | | | | | | | "rcu: Add rcutorture CPU-hotplug capability" adds cpu hotplug operations to the rcutorture code but produces a false positive warning about section mismatches: WARNING: vmlinux.o(.text+0x1e420c): Section mismatch in reference from the function rcu_torture_onoff() to the function .cpuinit.text:cpu_up() The function rcu_torture_onoff() references the function __cpuinit cpu_up(). This is often because rcu_torture_onoff lacks a __cpuinit annotation or the annotation of cpu_up is wrong. This commit therefore adds a __cpuinit annotation so the warning goes away. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Make rcutorture bool parameters really bool (core code)Rusty Russell2012-01-161-2/+2
| | | | | | | | | | | | | module_param(bool) used to counter-intuitively take an int. In fddd5201 (mid-2009) we allowed bool or int/unsigned int using a messy trick. It's time to remove the int/unsigned int option. For this version it'll simply give a warning, but it'll break next kernel version. This commit makes this change to rcutorture. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Add rcutorture tests for srcu_read_lock_raw()Paul E. McKenney2011-12-111-1/+25
| | | | | | | | | This commit adds simple rcutorture tests for srcu_read_lock_raw() and srcu_read_unlock_raw(). It does not test doing srcu_read_lock_raw() in an exception handler and releasing it in the corresponding process context. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Make rcutorture test for hotpluggability before offlining CPUsPaul E. McKenney2011-12-111-2/+2
| | | | | | | | | | | | | | | | | | The rcutorture test now can automatically exercise CPU hotplug and collect success statistics, which can be correlated with other rcutorture activity. This permits rcutorture to completely exercise RCU regardless of what sort of userspace and filesystem layout is in use. Unfortunately, rcutorture is happy to attempt to offline CPUs that cannot be offlined, for example, CPU 0 in both the x86 and ARM architectures. Although this allows rcutorture testing to proceed normally, it confounds attempts at error analysis due to the resulting flood of spurious CPU-hotplug errors. Therefore, this commit uses the new cpu_is_hotpluggable() function to avoid attempting to offline CPUs that are not hotpluggable, which in turn avoids spurious CPU-hotplug errors. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Add rcutorture CPU-hotplug capabilityPaul E. McKenney2011-12-111-5/+112
| | | | | | | | | | | | | Running CPU-hotplug operations concurrently with rcutorture has historically been a good way to find bugs in both RCU and CPU hotplug. This commit therefore adds an rcutorture module parameter called "onoff_interval" that causes a randomly selected CPU-hotplug operation to be executed at the specified interval, in seconds. The default value of "onoff_interval" is zero, which disables rcutorture-instigated CPU-hotplug operations. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Control rcutorture startup from kernel boot parametersPaul E. McKenney2011-12-111-0/+2
| | | | | | | | | | | | | Currently, if rcutorture is built into the kernel, it must be manually started or started from an init script. This is inconvenient for automated KVM testing, where it is good to be able to fully control rcutorture execution from the kernel parameters. This patch therefore adds a module parameter named "rcutorture_runnable" that defaults to zero ("don't start automatically"), but which can be set to one to cause rcutorture to start up immediately during boot. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Add rcutorture system-shutdown capabilityPaul E. McKenney2011-12-111-4/+64
| | | | | | | | | | | | | Although it is easy to run rcutorture tests under KVM, there is currently no nice way to run such a test for a fixed time period, collect all of the rcutorture data, and then shut the system down cleanly. This commit therefore adds an rcutorture module parameter named "shutdown_secs" that specified the run duration in seconds, after which rcutorture terminates the test and powers the system down. The default value for "shutdown_secs" is zero, which disables shutdown. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Add failure tracing to rcutorturePaul E. McKenney2011-12-111-0/+18
| | | | | | | | | Trace the rcutorture RCU accesses and dump the trace buffer when the first failure is detected. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: Make rcu_torture_boost() exit loops at end of testPaul E. McKenney2011-09-291-1/+2
| | | | | | | | | | One of the loops in rcu_torture_boost() fails to check kthread_should_stop(), and thus might be slowing or even stopping completion of rcutorture tests at rmmod time. This commit adds the kthread_should_stop() check to the offending loop. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Make rcu_torture_fqs() exit loops at end of testPaul E. McKenney2011-09-291-4/+6
| | | | | | | | | The rcu_torture_fqs() function can prevent the rcutorture tests from completing, resulting in a hang. This commit therefore ensures that rcu_torture_fqs() will exit its inner loops at the end of the test, and also applies the newish ULONG_CMP_LT() macro to time comparisons. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Allow rcutorture's stat_interval parameter to be changed at runtimePaul E. McKenney2011-09-291-1/+1
| | | | | | | | | | | | | | | When rcutorture is compiled directly into the kernel (instead of separately as a module), it is necessary to specify rcutorture.stat_interval as a kernel command-line parameter, otherwise, the rcu_torture_stats kthread is never started. However, when working with the system after it has booted, it is convenient to be able to change the time between statistic printing, particularly when logged into the console. This commit therefore allows the stat_interval parameter to be changed at runtime. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Don't destroy rcu_torture_boost() callback until it is donePaul E. McKenney2011-09-291-1/+1
| | | | | | | | | | The rcu_torture_boost() cleanup code destroyed debug-objects state before waiting for the last RCU callback to be invoked, resulting in rare but very real debug-objects warnings. Move the destruction to after the waiting to fix this problem. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Catch rcutorture up to new RCU API additionsPaul E. McKenney2011-09-291-34/+21
| | | | | | | | | | | | | Now that the RCU API contains synchronize_rcu_bh(), synchronize_sched(), call_rcu_sched(), and rcu_bh_expedited()... Make rcutorture test synchronize_rcu_bh(), getting rid of the old rcu_bh_torture_synchronize() workaround. Similarly, make rcutorture test synchronize_sched(), getting rid of the old sched_torture_synchronize() workaround. Make rcutorture test call_rcu_sched() instead of wrappering synchronize_sched(). Also add testing of rcu_bh_expedited(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Use kthread_create_on_node()Eric Dumazet2011-09-291-2/+3
| | | | | | | | | | | | | | | | | | | | | Commit a26ac2455ffc (move TREE_RCU from softirq to kthread) added per-CPU kthreads. However, kthread creation uses kthread_create(), which can put the kthread's stack and task struct on the wrong NUMA node. Therefore, use kthread_create_on_node() instead of kthread_create() so that the stacks and task structs are placed on the correct NUMA node. A similar change was carried out in commit 94dcf29a11b3 (kthread: use kthread_create_on_node()). Also change rcutorture's priority-boost-test kthread creation. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> CC: Tejun Heo <tj@kernel.org> CC: Rusty Russell <rusty@rustcorp.com.au> CC: Andrew Morton <akpm@linux-foundation.org> CC: Andi Kleen <ak@linux.intel.com> CC: Ingo Molnar <mingo@elte.hu> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* atomic: use <linux/atomic.h>Arun Sharma2011-07-271-1/+1
| | | | | | | | | | | | | | This allows us to move duplicated code in <asm/atomic.h> (atomic_inc_not_zero() for now) to <linux/atomic.h> Signed-off-by: Arun Sharma <asharma@fb.com> Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_checkMichal Hocko2011-07-081-2/+0
| | | | | | | | | | Since ca5ecddf (rcu: define __rcu address space modifier for sparse) rcu_dereference_check use rcu_read_lock_held as a part of condition automatically so callers do not have to do that as well. Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* rcu: mark rcutorture boosting callback as being on-stackPaul E. McKenney2011-05-061-0/+2
| | | | | | | | | | | | The CONFIG_DEBUG_OBJECTS_RCU_HEAD facility requires that on-stack RCU callbacks be flagged explicitly to debug-objects using the init_rcu_head_on_stack() and destroy_rcu_head_on_stack() functions. This commit applies those functions to the rcutorture code that tests RCU priority boosting. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: make rcutorture version numbers available through debugfsPaul E. McKenney2011-05-061-3/+5
| | | | | | | | | | It is not possible to accurately correlate rcutorture output with that of debugfs. This patch therefore adds a debugfs file that prints out the rcutorture version number, permitting easy correlation. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: eliminate unused boosting statisticsPaul E. McKenney2011-05-061-9/+1
| | | | | | | | | The n_rcu_torture_boost_allocerror and n_rcu_torture_boost_afferror statistics are not actually incremented anymore, so eliminate them. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: avoid hammering sched with yet another bound RT kthreadPaul E. McKenney2011-05-061-3/+3
| | | | | | | | | The scheduler does not appear to take kindly to having multiple real-time threads bound to a CPU that is going offline. So this commit is a temporary hack-around to avoid that happening. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcutorture: Get rid of duplicate sched.h includeJesper Juhl2011-03-041-1/+0
| | | | | | | | linux/sched.h is included twice in kernel/rcutorture.c - once is enough. Signed-off-by: Jesper Juhl <jj@chaosbits.net> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: add priority-inversion testing to rcutorturePaul E. McKenney2010-10-071-11/+259
| | | | | | | | | Add an optional test to force long-term preemption of RCU read-side critical sections, controlled by new test_boost, test_boost_interval, and test_boost_duration module parameters. This is to be used to test RCU priority boosting. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: fix sparse errors in rcutorture.cPaul E. McKenney2010-09-231-4/+7
| | | | | | | Add the sparse __rcu address-space identifier and make a couple of variables static. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcutorture: add random preemptionLai Jiangshan2010-08-201-0/+6
| | | | | | | | | | | | | Add random preemption to help we to torture the preemptable rcu. srcu_read_delay() also calls rcu_read_delay() for shorter delays. Added comment to preempt_schedule() call indicating that no quiescent states happen if preemption is disabled. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* sched_clock: Add local_clock() API and improve documentationPeter Zijlstra2010-06-091-2/+1
| | | | | | | | | | | | | | | | For people who otherwise get to write: cpu_clock(smp_processor_id()), there is now: local_clock(). Also, as per suggestion from Andrew, provide some documentation on the various clock interfaces, and minimize the unsigned long long vs u64 mess. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jens Axboe <jaxboe@fusionio.com> LKML-Reference: <1275052414.1645.52.camel@laptop> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Merge branch 'sched-core-for-linus' of ↵Linus Torvalds2010-05-181-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (49 commits) stop_machine: Move local variable closer to the usage site in cpu_stop_cpu_callback() sched, wait: Use wrapper functions sched: Remove a stale comment ondemand: Make the iowait-is-busy time a sysfs tunable ondemand: Solve a big performance issue by counting IOWAIT time as busy sched: Intoduce get_cpu_iowait_time_us() sched: Eliminate the ts->idle_lastupdate field sched: Fold updating of the last_update_time_info into update_ts_time_stats() sched: Update the idle statistics in get_cpu_idle_time_us() sched: Introduce a function to update the idle statistics sched: Add a comment to get_cpu_idle_time_us() cpu_stop: add dummy implementation for UP sched: Remove rq argument to the tracepoints rcu: need barrier() in UP synchronize_sched_expedited() sched: correctly place paranioa memory barriers in synchronize_sched_expedited() sched: kill paranoia check in synchronize_sched_expedited() sched: replace migration_thread with cpu_stop stop_machine: reimplement using cpu_stop cpu_stop: implement stop_cpu[s]() sched: Fix select_idle_sibling() logic in select_task_rq_fair() ...
| * sched: replace migration_thread with cpu_stopTejun Heo2010-05-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently migration_thread is serving three purposes - migration pusher, context to execute active_load_balance() and forced context switcher for expedited RCU synchronize_sched. All three roles are hardcoded into migration_thread() and determining which job is scheduled is slightly messy. This patch kills migration_thread and replaces all three uses with cpu_stop. The three different roles of migration_thread() are splitted into three separate cpu_stop callbacks - migration_cpu_stop(), active_load_balance_cpu_stop() and synchronize_sched_expedited_cpu_stop() - and each use case now simply asks cpu_stop to execute the callback as necessary. synchronize_sched_expedited() was implemented with private preallocated resources and custom multi-cpu queueing and waiting logic, both of which are provided by cpu_stop. synchronize_sched_expedited_count is made atomic and all other shared resources along with the mutex are dropped. synchronize_sched_expedited() also implemented a check to detect cases where not all the callback got executed on their assigned cpus and fall back to synchronize_sched(). If called with cpu hotplug blocked, cpu_stop already guarantees that and the condition cannot happen; otherwise, stop_machine() would break. However, this patch preserves the paranoid check using a cpumask to record on which cpus the stopper ran so that it can serve as a bisection point if something actually goes wrong theree. Because the internal execution state is no longer visible, rcu_expedited_torture_stats() is removed. This patch also renames cpu_stop threads to from "stopper/%d" to "migration/%d". The names of these threads ultimately don't matter and there's no reason to make unnecessary userland visible changes. With this patch applied, stop_machine() and sched now share the same resources. stop_machine() is faster without wasting any resources and sched migration users are much cleaner. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Josh Triplett <josh@freedesktop.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Dimitri Sivanich <sivanich@sgi.com>
* | rcu: remove all rcu head initializations, except on_stack initializationsPaul E. McKenney2010-05-121-0/+2
|/ | | | | | | | | Remove all rcu head inits. We don't care about the RCU head state before passing it to call_rcu() anyway. Only leave the "on_stack" variants so debugobjects can keep track of objects on stack. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* Merge branch 'for-linus' of ↵Linus Torvalds2010-03-031-4/+4
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: percpu: add __percpu sparse annotations to what's left percpu: add __percpu sparse annotations to fs percpu: add __percpu sparse annotations to core kernel subsystems local_t: Remove leftover local.h this_cpu: Remove pageset_notifier this_cpu: Page allocator conversion percpu, x86: Generic inc / dec percpu instructions local_t: Move local.h include to ringbuffer.c and ring_buffer_benchmark.c module: Use this_cpu_xx to dynamically allocate counters local_t: Remove cpu_local_xx macros percpu: refactor the code in pcpu_[de]populate_chunk() percpu: remove compile warnings caused by __verify_pcpu_ptr() percpu: make accessors check for percpu pointer in sparse percpu: add __percpu for sparse. percpu: make access macros universal percpu: remove per_cpu__ prefix.
| * Merge branch 'master' into percpuTejun Heo2010-01-051-16/+53
| |\ | | | | | | | | | | | | | | | Conflicts: arch/powerpc/platforms/pseries/hvCall.S include/linux/percpu.h
| * | percpu: remove per_cpu__ prefix.Rusty Russell2009-10-291-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that the return from alloc_percpu is compatible with the address of per-cpu vars, it makes sense to hand around the address of per-cpu variables. To make this sane, we remove the per_cpu__ prefix we used created to stop people accidentally using these vars directly. Now we have sparse, we can use that (next patch). tj: * Updated to convert stuff which were missed by or added after the original patch. * Kill per_cpu_var() macro. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
* | | rcu: Fix rcutorture mod_timer argument to delay one jiffyPaul E. McKenney2010-02-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current "mod_timer(&t, 1)" potentially makes the timer fire immediately, change this to wait one jiffy. Signed-off-by: Dan Carpenter <error27@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1266887105-1528-20-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | rcu: Introduce lockdep-based checking to RCU read-side primitivesPaul E. McKenney2010-02-251-2/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Inspection is proving insufficient to catch all RCU misuses, which is understandable given that rcu_dereference() might be protected by any of four different flavors of RCU (RCU, RCU-bh, RCU-sched, and SRCU), and might also/instead be protected by any of a number of locking primitives. It is therefore time to enlist the aid of lockdep. This set of patches is inspired by earlier work by Peter Zijlstra and Thomas Gleixner, and takes the following approach: o Set up separate lockdep classes for RCU, RCU-bh, and RCU-sched. o Set up separate lockdep classes for each instance of SRCU. o Create primitives that check for being in an RCU read-side critical section. These return exact answers if lockdep is fully enabled, but if unsure, report being in an RCU read-side critical section. (We want to avoid false positives!) The primitives are: For RCU: rcu_read_lock_held(void) For RCU-bh: rcu_read_lock_bh_held(void) For RCU-sched: rcu_read_lock_sched_held(void) For SRCU: srcu_read_lock_held(struct srcu_struct *sp) o Add rcu_dereference_check(), which takes a second argument in which one places a boolean expression based on the above primitives and/or lockdep_is_held(). o A new kernel configuration parameter, CONFIG_PROVE_RCU, enables rcu_dereference_check(). This depends on CONFIG_PROVE_LOCKING, and should be quite helpful during the transition period while CONFIG_PROVE_RCU-unaware patches are in flight. The existing rcu_dereference() primitive does no checking, but upcoming patches will change that. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1266887105-1528-1-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | rcu: Add force_quiescent_state() testing to rcutorturePaul E. McKenney2010-01-131-2/+78
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add force_quiescent_state() testing to rcutorture, with a separate thread that repeatedly invokes force_quiescent_state() in bursts. This can greatly increase the probability of encountering certain types of race conditions. Suggested-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1262646551116-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | Merge branch 'for-linus' of ↵Linus Torvalds2009-12-141-4/+4
|\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (34 commits) m68k: rename global variable vmalloc_end to m68k_vmalloc_end percpu: add missing per_cpu_ptr_to_phys() definition for UP percpu: Fix kdump failure if booted with percpu_alloc=page percpu: make misc percpu symbols unique percpu: make percpu symbols in ia64 unique percpu: make percpu symbols in powerpc unique percpu: make percpu symbols in x86 unique percpu: make percpu symbols in xen unique percpu: make percpu symbols in cpufreq unique percpu: make percpu symbols in oprofile unique percpu: make percpu symbols in tracer unique percpu: make percpu symbols under kernel/ and mm/ unique percpu: remove some sparse warnings percpu: make alloc_percpu() handle array types vmalloc: fix use of non-existent percpu variable in put_cpu_var() this_cpu: Use this_cpu_xx in trace_functions_graph.c this_cpu: Use this_cpu_xx for ftrace this_cpu: Use this_cpu_xx in nmi handling this_cpu: Use this_cpu operations in RCU this_cpu: Use this_cpu ops for VM statistics ... Fix up trivial (famous last words) global per-cpu naming conflicts in arch/x86/kvm/svm.c mm/slab.c
| * this_cpu: Use this_cpu operations in RCUChristoph Lameter2009-10-031-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | RCU does not do dynamic allocations but it increments per cpu variables a lot. These instructions results in a move to a register and then back to memory. This patch will make it use the inc/dec instructions on x86 that do not need a register. Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Tejun Heo <tj@kernel.org>
* | rcu: Add expedited grace-period support for preemptible RCUPaul E. McKenney2009-12-031-9/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Implement an synchronize_rcu_expedited() for preemptible RCU that actually is expedited. This uses synchronize_sched_expedited() to force all threads currently running in a preemptible-RCU read-side critical section onto the appropriate ->blocked_tasks[] list, then takes a snapshot of all of these lists and waits for them to drain. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1259784616158-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | rcu: Improve rcutorture diagnostics when bad torture_type specifiedPaul E. McKenney2009-10-261-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make rcutorture list the available torture_type values when it doesn't like the one specified. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com Cc: avi@redhat.com Cc: mtosatti@redhat.com LKML-Reference: <12565226351868-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | rcu: Add synchronize_srcu_expedited() to the rcutorture test suitePaul E. McKenney2009-10-261-3/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Adds the "srcu_expedited" torture type, and also renames sched_ops_sync to sched_sync_ops for consistency while we are in this file. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com Cc: avi@redhat.com Cc: mtosatti@redhat.com LKML-Reference: <12565226353636-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | rcu: Clean up code to address Ingo's checkpatch feedbackPaul E. McKenney2009-09-231-3/+1
|/ | | | | | | | | | | | | | | | | | | Move declarations and update storage classes to make checkpatch happy. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <12537246441701-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcu: Fix whitespace inconsistenciesPaul E. McKenney2009-09-191-13/+15
| | | | | | | | | | | | | | | | | | | | Fix a number of whitespace ^Ierrors in the include/linux/rcu* and the kernel/rcu* files. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu LKML-Reference: <20090918172819.GA24405@linux.vnet.ibm.com> [ did more checkpatch fixlets ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcutorture: Occasionally delay readers enough to make RCU force_quiescent_stateJosh Triplett2009-09-181-6/+9
| | | | | | | | | | | | | | | | | | | | rcutorture already delays readers, but never for long enough to make RCU force a quiescent state. Add an occasional delay of 50ms. Signed-off-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josht@linux.vnet.ibm.com Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org LKML-Reference: <12524504772607-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* rcu: Add synchronize_sched_expedited() torture testsPaul E. McKenney2009-07-031-92/+110
| | | | | | | | | | | | | | | | | | | | | | This patch adds rcutorture tests for the new synchronize_sched_expedited() primitive, and also does some whitespace cleanups in kernel/rcutorture.c as well. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Cc: davem@davemloft.net Cc: dada1@cosmosbay.com Cc: zbr@ioremap.net Cc: jeff.chua.linux@gmail.com Cc: paulus@samba.org Cc: laijs@cn.fujitsu.com Cc: jengelh@medozas.de Cc: r000n@r000n.net Cc: benh@kernel.crashing.org Cc: mathieu.desnoyers@polymtl.ca LKML-Reference: <12459460981342-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* cpumask: convert rcutorture.cRusty Russell2009-03-301-8/+17
| | | | | | | | | | | We're getting rid of cpumasks on the stack. Simply change tmp_mask to a global, and allocate it in rcu_torture_init(). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Josh Triplett <josh@freedesktop.org>
* rcu: fix bug in rcutorture system-shutdown codePaul E. McKenney2009-01-071-45/+68
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes an rcutorture bug found by Eric Sesterhenn that resulted in oopses in response to "rmmod rcutorture". The problem was in some new code that attempted to handle the case where a system is shut down while rcutorture is still running, for example, when rcutorture is built into the kernel so that it cannot be removed. The fix causes the rcutorture threads to "park" in an schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT) rather than trying to get them to terminate cleanly. Concurrent shutdown and rmmod is illegal. I believe that this is 2.6.29 material, as it is used in some testing setups. For reference, here are the rcutorture operating modes: CONFIG_RCU_TORTURE_TEST=m This is the normal rcutorture build. Use "modprobe rcutorture" (with optional arguments) to start, and "rmmod rcutorture" to stop. If you shut the system down without doing the rmmod, you should see console output like: rcutorture thread rcu_torture_writer parking due to system shutdown One for each rcutorture kthread. CONFIG_RCU_TORTURE_TEST=y CONFIG_RCU_TORTURE_TEST_RUNNABLE=n Use this if you want rcutorture built in, but don't want the test to start running during early boot. To start the torturing: echo 1 > /proc/sys/kernel/rcutorture_runnable To stop the torturing, s/1/0/ You will get "parking" console messages as noted above when you shut the system down. CONFIG_RCU_TORTURE_TEST=y CONFIG_RCU_TORTURE_TEST_RUNNABLE=y Same as above, except that the torturing starts during early boot. Only for the stout of heart and strong of stomach. The same /proc entry noted above may be used to control the test. Located-by: Eric Sesterhenn <snakebyte@gmx.de> Tested-by: Eric Sesterhenn <snakebyte@gmx.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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