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* doc: CPU-hotplug notifiers cannot invoke synchronize_srcu() or srcu_barrier()Paul E. McKenney2019-01-261-7/+13
| | | | | | | | | | | | | | | | | SRCU's synchronize_srcu() may not be invoked from CPU-hotplug notifiers, due to the fact that SRCU grace periods make use of timers and the possibility of timers being temporarily stranded on the outgoing CPU. This stranding of timers means that timers posted to the outgoing CPU will not fire until late in the CPU-hotplug process. The problem is that if a notifier is waiting on an SRCU grace period, that grace period is waiting on a timer, and that timer is stranded on the outgoing CPU, then the notifier will never be awakened, in other words, deadlock has occurred. This same situation of course also prohibits srcu_barrier() from being invoked from CPU-hotplug notifiers. This commit therefore updates the requirements to include this restriction. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* doc: Now jiffies_till_sched_qs solicits help from cond_resched()Paul E. McKenney2019-01-261-13/+14
| | | | | | | | | The rcutree.jiffies_till_sched_qs kernel boot parameter used to solicit help only from rcu_note_context_switch(), but now also solicits help from cond_resched(). This commit therefore updates kernel-parameters.txt accordingly. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* Merge branches 'consolidate.2019.01.26a' and 'fwd.2019.01.26a' into HEADPaul E. McKenney2019-01-264-78/+114
|\ | | | | | | | | consolidate.2019.01.26a: RCU flavor consolidation cleanups. fwd.2019.01.26a: RCU grace-period forward-progress fixes.
| * rcu: Prevent needless ->gp_seq_needed update in __note_gp_changes()Zhang, Jun2019-01-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, __note_gp_changes() checks to see if the rcu_node structure's ->gp_seq_needed is greater than or equal to that of the rcu_data structure, and if so, updates the rcu_data structure's ->gp_seq_needed field. This results in a useless store in the case where the two fields are equal. This commit therefore carries out this store only in the case where the rcu_node structure's ->gp_seq_needed is strictly greater than that of the rcu_data structure. Signed-off-by: "Zhang, Jun" <jun.zhang@intel.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Link: https://lkml.kernel.org/r/88DC34334CA3444C85D647DBFA962C2735AD5F77@SHSMSX104.ccr.corp.intel.com
| * rcu: Do RCU GP kthread self-wakeup from softirq and interruptZhang, Jun2019-01-261-6/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The rcu_gp_kthread_wake() function is invoked when it might be necessary to wake the RCU grace-period kthread. Because self-wakeups are normally a useless waste of CPU cycles, if rcu_gp_kthread_wake() is invoked from this kthread, it naturally refuses to do the wakeup. Unfortunately, natural though it might be, this heuristic fails when rcu_gp_kthread_wake() is invoked from an interrupt or softirq handler that interrupted the grace-period kthread just after the final check of the wait-event condition but just before the schedule() call. In this case, a wakeup is required, even though the call to rcu_gp_kthread_wake() is within the RCU grace-period kthread's context. Failing to provide this wakeup can result in grace periods failing to start, which in turn results in out-of-memory conditions. This race window is quite narrow, but it actually did happen during real testing. It would of course need to be fixed even if it was strictly theoretical in nature. This patch does not Cc stable because it does not apply cleanly to earlier kernel versions. Fixes: 48a7639ce80c ("rcu: Make callers awaken grace-period kthread") Reported-by: "He, Bo" <bo.he@intel.com> Co-developed-by: "Zhang, Jun" <jun.zhang@intel.com> Co-developed-by: "He, Bo" <bo.he@intel.com> Co-developed-by: "xiao, jin" <jin.xiao@intel.com> Co-developed-by: Bai, Jie A <jie.a.bai@intel.com> Signed-off: "Zhang, Jun" <jun.zhang@intel.com> Signed-off: "He, Bo" <bo.he@intel.com> Signed-off: "xiao, jin" <jin.xiao@intel.com> Signed-off: Bai, Jie A <jie.a.bai@intel.com> Signed-off-by: "Zhang, Jun" <jun.zhang@intel.com> [ paulmck: Switch from !in_softirq() to "!in_interrupt() && !in_serving_softirq() to avoid redundant wakeups and to also handle the interrupt-handler scenario as well as the softirq-handler scenario that actually occurred in testing. ] Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Link: https://lkml.kernel.org/r/CD6925E8781EFD4D8E11882D20FC406D52A11F61@SHSMSX104.ccr.corp.intel.com
| * rcu: Add sysrq rcu_node-dump capabilityPaul E. McKenney2019-01-262-0/+30
| | | | | | | | | | | | | | | | | | | | | | Life is hard if RCU manages to get stuck without triggering RCU CPU stall warnings or triggering the rcu_check_gp_start_stall() checks for failing to start a grace period. This commit therefore adds a boot-time-selectable sysrq key (commandeering "y") that allows manually dumping Tree RCU state. The new rcutree.sysrq_rcu kernel boot parameter must be set for this sysrq to be available. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| * rcu: Protect rcu_check_gp_kthread_starvation() access to ->gp_flagsPaul E. McKenney2019-01-261-1/+1
| | | | | | | | | | | | | | | | | | The rcu_check_gp_kthread_starvation() function can be invoked without holding locks, so the access to the rcu_state structure's ->gp_flags field must be protected with READ_ONCE(). This commit therefore adds this protection. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| * rcu: Improve diagnostics for failed RCU grace-period startPaul E. McKenney2019-01-262-23/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | If a grace period fails to start (for example, because you commented out the last two lines of rcu_accelerate_cbs_unlocked()), rcu_core() will invoke rcu_check_gp_start_stall(), which will notice and complain. However, this complaint is lacking crucial debugging information such as when the last wakeup executed and what the value of ->gp_seq was at that time. This commit therefore removes the current pr_alert() from rcu_check_gp_start_stall(), instead invoking show_rcu_gp_kthreads(), which has been updated to print the needed information, which is collected by rcu_gp_kthread_wake(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| * rcu: Update NOCB commentsPaul E. McKenney2019-01-261-17/+16
| | | | | | | | | | | | | | This commit updates a few obsolete comments in the RCU callback-offload code. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| * rcu: Remove unused rcu_cpu_kthread_cpu per-CPU variablePaul E. McKenney2019-01-261-4/+0
| | | | | | | | | | | | | | The rcu_cpu_kthread_cpu used to provide debugfs information, but is no longer used. This commit therefore removes it. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| * rcu: Move rcu_cpu_has_work to rcu_data structurePaul E. McKenney2019-01-262-13/+5
| | | | | | | | | | | | | | | | | | | | | | | | Given that RCU has a perfectly good per-CPU rcu_data structure, most per-CPU quantities should be stored there. This commit therefore moves the rcu_cpu_has_work per-CPU variable to the rcu_data structure. This also makes this variable unconditionally present, which should be acceptable given the memory reduction due to the RCU flavor consolidation and also due to simplifications this will enable. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| * rcu: Remove unused rcu_cpu_kthread_loops per-CPU variablePaul E. McKenney2019-01-262-3/+0
| | | | | | | | | | | | | | The rcu_cpu_kthread_loops variable used to provide debugfs information, but is no longer used. This commit therefore removes it. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| * rcu: Move rcu_cpu_kthread_status to rcu_data structurePaul E. McKenney2019-01-262-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | Given that RCU has a perfectly good per-CPU rcu_data structure, most per-CPU quantities should be stored there. This commit therefore moves the rcu_cpu_kthread_status per-CPU variable to the rcu_data structure. This also makes this variable unconditionally present, which should be acceptable given the memory reduction due to the RCU flavor consolidation and also due to simplifications this will enable. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| * rcu: Move rcu_cpu_kthread_task to rcu_data structurePaul E. McKenney2019-01-262-7/+10
| | | | | | | | | | | | | | | | | | | | | | | | Given that RCU has a perfectly good per-CPU rcu_data structure, most per-CPU quantities should be stored there. This commit therefore moves the rcu_cpu_kthread_task per-CPU variable to the rcu_data structure. This also makes this variable unconditionally present, which should be acceptable given the memory reduction due to the RCU flavor consolidation and also due to simplifications this will enable. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| * rcu: Accommodate zero jiffies_till_first_fqs and kthread kickingPaul E. McKenney2019-01-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It is perfectly fine to set the rcutree.jiffies_till_first_fqs boot parameter to zero, in fact, this can be useful on specialty systems that usually have at least one idle CPU and that need fast grace periods. This is because this setting causes the RCU grace-period kthread to scan for idle threads immediately after grace-period initialization, as opposed to waiting several jiffies to do so. It is also perfectly fine to set the rcutree.rcu_kick_kthreads kernel parameter, which gives the RCU grace-period kthread an extra wakeup if it doesn't make progress for a period of three times the setting of the rcutree.jiffies_till_first_fqs boot parameter. This is of course problematic when the value of this parameter is zero, as it can result in unnecessary wakeup IPIs along with unnecessary WARN_ONCE() invocations. This commit therefore defers kthread kicking for at least two jiffies, regardless of the setting of rcutree.jiffies_till_first_fqs. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Remove wrapper definitions for obsolete RCU update functionsPaul E. McKenney2019-01-261-53/+0
| | | | | | | | | | | | | | | | | | | | None of synchronize_rcu_bh, synchronize_rcu_bh_expedited, call_rcu_bh, rcu_barrier_bh, synchronize_sched, synchronize_sched_expedited, call_rcu_sched, rcu_barrier_sched, get_state_synchronize_sched, and cond_synchronize_sched are actually used. This commit therefore removes their trivial wrapper-function definitions. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Discard separate per-CPU callback countsPaul E. McKenney2019-01-264-75/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Back when there were multiple flavors of RCU, it was necessary to separately count lazy and non-lazy callbacks for each CPU. These counts were used in CONFIG_RCU_FAST_NO_HZ kernels to determine how long a newly idle CPU should be allowed to sleep before handling its RCU callbacks. But now that there is only one flavor, the callback counts for a given CPU's sole rcu_data structure are the counts for that CPU. This commit therefore removes the rcu_data structure's ->nonlazy_posted and ->nonlazy_posted_snap fields, the rcu_idle_count_callbacks_posted() and rcu_cpu_has_callbacks() functions, repurposes the rcu_data structure's ->all_lazy field to record the laziness state at the beginning of the latest idle sojourn, and modifies CONFIG_RCU_FAST_NO_HZ RCU CPU stall warnings accordingly. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Inline _synchronize_rcu_expedited() into synchronize_rcu_expedited()Paul E. McKenney2019-01-261-45/+36
| | | | | | | | | | | | | | | | Now that _synchronize_rcu_expedited() has only one caller, and given that this is a tail call, this commit inlines _synchronize_rcu_expedited() into synchronize_rcu_expedited(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Consolidate PREEMPT and !PREEMPT synchronize_rcu()Paul E. McKenney2019-01-263-91/+73
| | | | | | | | | | | | | | | | | | | | Now that rcu_blocking_is_gp() makes the correct immediate-return decision for both PREEMPT and !PREEMPT, a single implementation of synchronize_rcu() will work correctly under both configurations. This commit therefore eliminates a few lines of code by consolidating the two implementations of synchronize_rcu(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Consolidate PREEMPT and !PREEMPT synchronize_rcu_expedited()Paul E. McKenney2019-01-261-56/+49
| | | | | | | | | | | | | | | | | | | | The CONFIG_PREEMPT=n and CONFIG_PREEMPT=y implementations of synchronize_rcu_expedited() are quite similar, and with small modifications to rcu_blocking_is_gp() can be made identical. This commit therefore makes this change in order to save a few lines of code and to reduce the amount of duplicate code. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Determine expedited-GP IPI handler at build timePaul E. McKenney2019-01-264-37/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Back when there could be multiple RCU flavors running in the same kernel at the same time, it was necessary to specify the expedited grace-period IPI handler at runtime. Now that there is only one RCU flavor, the IPI handler can be determined at build time. There is therefore no longer any reason for the RCU-preempt and RCU-sched IPI handlers to have different names, nor is there any reason to pass these handlers in function arguments and in the data structures enclosing workqueues. This commit therefore makes all these changes, pushing the specification of the expedited grace-period IPI handler down to the point of use. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Inline rcu_kthread_do_work() into its sole remaining callerPaul E. McKenney2019-01-261-6/+1
| | | | | | | | | | | | | | | | The rcu_kthread_do_work() function has a single-line body and only one remaining caller. This commit therefore saves a few lines of code by inlining rcu_kthread_do_work() into its sole remaining caller. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Eliminate RCU_BH_FLAVOR and RCU_SCHED_FLAVORPaul E. McKenney2019-01-262-4/+0
| | | | | | | | | | | | | | | | Now that the RCU flavors have been consolidated, RCU_BH_FLAVOR and RCU_SCHED_FLAVOR are no longer used. This commit therefore saves a few lines by removing them. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Inline force_quiescent_state() into rcu_force_quiescent_state()Paul E. McKenney2019-01-261-15/+6
| | | | | | | | | | | | | | | | | | | | Given that rcu_force_quiescent_state() is a simple wrapper around force_quiescent_state(), this commit saves a few lines of code by inlining force_quiescent_state() into rcu_force_quiescent_state(), and changing all references to force_quiescent_state() to instead invoke rcu_force_quiescent_state(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Make expedited IPI handler return after handling critical sectionPaul E. McKenney2019-01-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | During expedited RCU grace-period initialization, IPIs are sent to all non-idle online CPUs. The IPI handler checks to see if the CPU is in quiescent state, reporting one if so. This handler looks at three different cases: (1) The CPU is not in an rcu_read_lock()-based critical section, (2) The CPU is in the process of exiting an rcu_read_lock()-based critical section, and (3) The CPU is in an rcu_read_lock()-based critical section. In case (2), execution falls through into case (3). This is harmless from a functionality viewpoint, but can result in needless overhead during an improbable corner case. This commit therefore adds the "return" statement needed to prevent fall-through. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | rcu: Rename and comment changes due to only one rcuo kthread per CPUPaul E. McKenney2019-01-263-6/+6
| | | | | | | | | | | | | | | | | | | | Given RCU flavor consolidation, the name rcu_spawn_all_nocb_kthreads() is quite misleading. It no longer ever creates more than one kthread, and it does so only for the specified CPU. This commit therefore changes this name to the more descriptive rcu_spawn_cpu_nocb_kthread(), and also fixes up a similar issue in its header comment while in the area. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* | sched: Replace synchronize_sched() with synchronize_rcu()Paul E. McKenney2019-01-262-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | Now that synchronize_rcu() waits for preempt-disable regions of code as well as RCU read-side critical sections, synchronize_sched() can be replaced by synchronize_rcu(), in fact, synchronize_sched() is now completely equivalent to synchronize_rcu(). This commit therefore replaces synchronize_sched() with synchronize_rcu() so that synchronize_sched() can eventually be removed entirely. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
* | sched: Replace call_rcu_sched() with call_rcu()Paul E. McKenney2019-01-262-3/+3
|/ | | | | | | | | | | | | | Now that call_rcu()'s callback is not invoked until after all preempt-disable regions of code have completed (in addition to explicitly marked RCU read-side critical sections), call_rcu() can be used in place of call_rcu_sched(). This commit therefore makes that change. While in the area, this commit also updates an outdated header comment for for_each_domain(). Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
* tools/memory-model: Make scripts take "-j" abbreviation for "--jobs"Paul E. McKenney2019-01-211-2/+12
| | | | | | | | | | | | | | | | | | | | | | | The "--jobs" argument to the litmus-test scripts is similar to the "-jN" argument to "make", so this commit allows the "-jN" form as well. While in the area, it also prohibits the various forms of "-j0". Suggested-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akiyks@gmail.com Cc: boqun.feng@gmail.com Cc: dhowells@redhat.com Cc: j.alglave@ucl.ac.uk Cc: linux-arch@vger.kernel.org Cc: luc.maranget@inria.fr Cc: npiggin@gmail.com Cc: parri.andrea@gmail.com Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/20181203230451.28921-3-paulmck@linux.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* tools/memory-model: Add scripts to check github litmus testsPaul E. McKenney2019-01-2113-93/+739
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The https://github.com/paulmckrcu/litmus repository contains a large number of C-language litmus tests that include "Result:" comments predicting the verification result. This commit adds a number of scripts that run tests on these litmus tests: checkghlitmus.sh: Runs all litmus tests in the https://github.com/paulmckrcu/litmus archive that are C-language and that have "Result:" comment lines documenting expected results, comparing the actual results to those expected. Clones the repository if it has not already been cloned into the "tools/memory-model/litmus" directory. initlitmushist.sh Run all litmus tests having no more than the specified number of processes given a specified timeout, recording the results in .litmus.out files. Clones the repository if it has not already been cloned into the "tools/memory-model/litmus" directory. newlitmushist.sh For all new or updated litmus tests having no more than the specified number of processes given a specified timeout, run and record the results in .litmus.out files. checklitmushist.sh Run all litmus tests having .litmus.out files from previous initlitmushist.sh or newlitmushist.sh runs, comparing the herd output to that of the original runs. The above scripts will run litmus tests concurrently, by default with one job per available CPU. Giving any of these scripts the --help argument will cause them to print usage information. This commit also adds a number of helper scripts that are not intended to be invoked from the command line: cmplitmushist.sh: Compare the output of two different runs of the same litmus test. judgelitmus.sh: Compare the output of a litmus test to its "Result:" comment line. parseargs.sh: Parse command-line arguments. runlitmushist.sh: Run the litmus tests whose pathnames are provided one per line on standard input. While in the area, this commit also makes the existing checklitmus.sh and checkalllitmus.sh scripts use parseargs.sh in order to provide a bit of uniformity. In addition, per-litmus-test status output is directed to stdout, while end-of-test summary information is directed to stderr. Finally, the error flag standardizes on "!!!" to assist those familiar with rcutorture output. The defaults for the parseargs.sh arguments may be overridden by using environment variables: LKMM_DESTDIR for --destdir, LKMM_HERD_OPTIONS for --herdoptions, LKMM_JOBS for --jobs, LKMM_PROCS for --procs, and LKMM_TIMEOUT for --timeout. [ paulmck: History-check summary-line changes per Alan Stern feedback. ] Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akiyks@gmail.com Cc: boqun.feng@gmail.com Cc: dhowells@redhat.com Cc: j.alglave@ucl.ac.uk Cc: linux-arch@vger.kernel.org Cc: luc.maranget@inria.fr Cc: npiggin@gmail.com Cc: parri.andrea@gmail.com Cc: stern@rowland.harvard.edu Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/20181203230451.28921-2-paulmck@linux.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* tools/memory-model: Model smp_mb__after_unlock_lock()Andrea Parri2019-01-213-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kernel documents smp_mb__after_unlock_lock() the following way: "Place this after a lock-acquisition primitive to guarantee that an UNLOCK+LOCK pair acts as a full barrier. This guarantee applies if the UNLOCK and LOCK are executed by the same CPU or if the UNLOCK and LOCK operate on the same lock variable." Formalize in LKMM the above guarantee by defining (new) mb-links according to the law: ([M] ; po ; [UL] ; (co | po) ; [LKW] ; fencerel(After-unlock-lock) ; [M]) where the component ([UL] ; co ; [LKW]) identifies "UNLOCK+LOCK pairs on the same lock variable" and the component ([UL] ; po ; [LKW]) identifies "UNLOCK+LOCK pairs executed by the same CPU". In particular, the LKMM forbids the following two behaviors (the second litmus test below is based on: Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html c.f., Section "Tree RCU Grace Period Memory Ordering Building Blocks"): C after-unlock-lock-same-cpu (* * Result: Never *) {} P0(spinlock_t *s, spinlock_t *t, int *x, int *y) { int r0; spin_lock(s); WRITE_ONCE(*x, 1); spin_unlock(s); spin_lock(t); smp_mb__after_unlock_lock(); r0 = READ_ONCE(*y); spin_unlock(t); } P1(int *x, int *y) { int r0; WRITE_ONCE(*y, 1); smp_mb(); r0 = READ_ONCE(*x); } exists (0:r0=0 /\ 1:r0=0) C after-unlock-lock-same-lock-variable (* * Result: Never *) {} P0(spinlock_t *s, int *x, int *y) { int r0; spin_lock(s); WRITE_ONCE(*x, 1); r0 = READ_ONCE(*y); spin_unlock(s); } P1(spinlock_t *s, int *y, int *z) { int r0; spin_lock(s); smp_mb__after_unlock_lock(); WRITE_ONCE(*y, 1); r0 = READ_ONCE(*z); spin_unlock(s); } P2(int *z, int *x) { int r0; WRITE_ONCE(*z, 1); smp_mb(); r0 = READ_ONCE(*x); } exists (0:r0=0 /\ 1:r0=0 /\ 2:r0=0) Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Akira Yokosawa <akiyks@gmail.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Daniel Lustig <dlustig@nvidia.com> Cc: David Howells <dhowells@redhat.com> Cc: Jade Alglave <j.alglave@ucl.ac.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luc Maranget <luc.maranget@inria.fr> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-arch@vger.kernel.org Cc: parri.andrea@gmail.com Link: http://lkml.kernel.org/r/20181203230451.28921-1-paulmck@linux.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdmaLinus Torvalds2019-01-1810-22/+109
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull rdma fixes frfom Jason Gunthorpe: "Not much so far. We have the usual batch of bugs and two fixes to code merged this cycle: - Restore valgrind support for the ioctl verbs interface merged this window, and fix a missed error code on an error path from that conversion - A user reported crash on obsolete mthca hardware - pvrdma was using the wrong command opcode toward the hypervisor - NULL pointer crash regression when dumping rdma-cm over netlink - Be conservative about exposing the global rkey" * tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: RDMA/uverbs: Mark ioctl responses with UVERBS_ATTR_F_VALID_OUTPUT RDMA/mthca: Clear QP objects during their allocation RDMA/vmw_pvrdma: Return the correct opcode when creating WR RDMA/cma: Add cm_id restrack resource based on kernel or user cm_id type RDMA/nldev: Don't expose unsafe global rkey to regular user RDMA/uverbs: Fix post send success return value in case of error
| * RDMA/uverbs: Mark ioctl responses with UVERBS_ATTR_F_VALID_OUTPUTJason Gunthorpe2019-01-144-13/+59
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When the ioctl interface for the write commands was introduced it did not mark the core response with UVERBS_ATTR_F_VALID_OUTPUT. This causes rdma-core in userspace to not mark the buffers as written for valgrind. Along the same lines it turns out we have always missed marking the driver data. Fixing both of these makes valgrind work properly with rdma-core and ioctl. Fixes: 4785860e04bc ("RDMA/uverbs: Implement an ioctl that can call write and write_ex handlers") Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> Reviewed-by: Artemy Kovalyov <artemyko@mellanox.com> Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
| * RDMA/mthca: Clear QP objects during their allocationLeon Romanovsky2019-01-111-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As part of audit process to update drivers to use rdma_restrack_add() ensure that QP objects is cleared before access. Such change fixes the crash observed with uninitialized non zero sgid attr accessed by ib_destroy_qp(). CPU: 3 PID: 74 Comm: kworker/u16:1 Not tainted 4.19.10-300.fc29.x86_64 Workqueue: ipoib_wq ipoib_cm_tx_reap [ib_ipoib] RIP: 0010:rdma_put_gid_attr+0x9/0x30 [ib_core] RSP: 0018:ffffb7ad819dbde8 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff8d1bdf5a2e00 RCX: 0000000000002699 RDX: 206c656e72656af8 RSI: ffff8d1bf7ae6160 RDI: 206c656e72656b20 RBP: 0000000000000000 R08: 0000000000026160 R09: ffffffffc06b45bf R10: ffffe849887da000 R11: 0000000000000002 R12: ffff8d1be30cb400 R13: ffff8d1bdf681800 R14: ffff8d1be2272400 R15: ffff8d1be30ca000 FS: 0000000000000000(0000) GS:ffff8d1bf7ac0000(0000) knlGS:0000000000000000 Trace: ib_destroy_qp+0xc9/0x240 [ib_core] ipoib_cm_tx_reap+0x1f9/0x4e0 [ib_ipoib] process_one_work+0x1a1/0x3a0 worker_thread+0x30/0x380 ? pwq_unbound_release_workfn+0xd0/0xd0 kthread+0x112/0x130 ? kthread_create_worker_on_cpu+0x70/0x70 ret_from_fork+0x22/0x40 Reported-by: Alexander Murashkin <AlexanderMurashkin@msn.com> Tested-by: Alexander Murashkin <AlexanderMurashkin@msn.com> Fixes: 1a1f460ff151 ("RDMA: Hold the sgid_attr inside the struct ib_ah/qp") Signed-off-by: Parav Pandit <parav@mellanox.com> Signed-off-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
| * RDMA/vmw_pvrdma: Return the correct opcode when creating WRAdit Ranadive2019-01-113-1/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Since the IB_WR_REG_MR opcode value changed, let's set the PVRDMA device opcodes explicitly. Reported-by: Ruishuang Wang <ruishuangw@vmware.com> Fixes: 9a59739bd01f ("IB/rxe: Revise the ib_wr_opcode enum") Cc: stable@vger.kernel.org Reviewed-by: Bryan Tan <bryantan@vmware.com> Reviewed-by: Ruishuang Wang <ruishuangw@vmware.com> Reviewed-by: Vishnu Dasa <vdasa@vmware.com> Signed-off-by: Adit Ranadive <aditr@vmware.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
| * RDMA/cma: Add cm_id restrack resource based on kernel or user cm_id typeSteve Wise2019-01-091-1/+4
| | | | | | | | | | | | | | | | | | | | A recent regression causes a null ptr crash when dumping cm_id resources. The cma is incorrectly adding all cm_id restrack resources as kernel mode. Fixes: af8d70375d56 ("RDMA/restrack: Resource-tracker should not use uobject pointers") Signed-off-by: Steve Wise <swise@opengridcomputing.com> Reviewed-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
| * RDMA/nldev: Don't expose unsafe global rkey to regular userLeon Romanovsky2019-01-071-4/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | Unsafe global rkey is considered dangerous because it exposes memory registered for all memory in the system. Only users with a QP on the same PD can use the rkey, and generally those QPs will already know the value. However, out of caution, do not expose the value to unprivleged users on the local system. Require CAP_NET_ADMIN instead. Cc: <stable@vger.kernel.org> # 4.16 Fixes: 29cf1351d450 ("RDMA/nldev: provide detailed PD information") Signed-off-by: Leon Romanovsky <leonro@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
| * RDMA/uverbs: Fix post send success return value in case of errorGal Pressman2019-01-071-1/+3
| | | | | | | | | | | | | | | | If get QP object fails 'ret' must be assigned with a proper error code. Fixes: 9a0738575f26 ("RDMA/uverbs: Use uverbs_response() for remaining response copying") Signed-off-by: Gal Pressman <galpress@amazon.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* | Merge tag 'drm-fixes-2019-01-18' of git://anongit.freedesktop.org/drm/drmLinus Torvalds2019-01-1827-131/+114
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull drm fixes from Dave Airlie: "The rc3 fixes are a bit scattered: - meson, sun4i and rockchip all had missing of_node_put. - qxl and virtio both were advertising dma-buf to userspace when they really shouldn't have. Otherwise: meson: - modesetting regression fix i915 GVT: - one cmd parser failure fix - region cleanup fix in vGPU destroy amdgpu: - KFD fixes for arm64 mixed APU/DGPU - vega12 powerplay fix - raven DC fixes - freesync fix" * tag 'drm-fixes-2019-01-18' of git://anongit.freedesktop.org/drm/drm: drm/amd/display: Detach backlight from stream drm/sun4i: backend: add missing of_node_puts Revert "drm/amdgpu: validate user pitch alignment" Revert "drm/amdgpu: validate user GEM object size" drm/meson: Fix atomic mode switching regression drm/i915/gvt: Fix mmap range check drm/i915/gvt: free VFIO region space in vgpu detach drm/amd/display: Fix disabled cursor on top screen edge drm/amd/display: fix warning on raven hotplug drm/amd/display: fix PME notification not working in RV desktop drm/amd/display: Only get the connector state for VRR when toggled drm/amd/display: Pack DMCU iRAM alignment drm/amd/powerplay: run acg btc for Vega12 drm/amdkfd: Don't assign dGPUs to APU topology devices drm/amdkfd: Allow building KFD on ARM64 (v2) drm/meson: add missing of_node_put drm/virtio: drop prime import/export callbacks drm/qxl: drop prime import/export callbacks drm/i915/gvt: Allow F_CMD_ACCESS on mmio 0x21f0 drm/rockchip: add missing of_node_put
| * \ Merge tag 'drm-misc-fixes-2019-01-17' of ↵Dave Airlie2019-01-189-66/+20
| |\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://anongit.freedesktop.org/drm/drm-misc into drm-fixes drm-misc-fixes for v5.0-rc3: - Add missing calls to of_node_put to sun4i, meson, and rockchip. - Drop unimplemented prime callbacks in virtio and qxl, so support for prime is not advertised on those drivers. - Fix mode switching regression in meson. Signed-off-by: Dave Airlie <airlied@redhat.com> From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/9af07312-f435-2fda-65a2-9fe92cdf5da4@linux.intel.com
| | * | drm/sun4i: backend: add missing of_node_putsJulia Lawall2019-01-151-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The device node iterators perform an of_node_get on each iteration, so a jump out of the loop requires an of_node_put. Remote and port also have augmented reference counts, so drop them on each iteration and at the end of the function, respectively. Remote is only used for the address it contains, not for the contents of that address, so the reference count can be dropped immediately. The semantic patch that fixes the first part of this problem is as follows (http://coccinelle.lip6.fr): // <smpl> @@ expression root,e; local idexpression child; iterator name for_each_child_of_node; @@ for_each_available_child_of_node(root, child) { ... when != of_node_put(child) when != e = child + of_node_put(child); ? break; ... } ... when != child // </smpl> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com> Link: https://patchwork.freedesktop.org/patch/msgid/1547369264-24831-5-git-send-email-Julia.Lawall@lip6.fr
| | * | drm/meson: Fix atomic mode switching regressionNeil Armstrong2019-01-152-21/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit 2bcd3ecab773 when switching mode from X11 (ubuntu mate for example) the display gets blurry, looking like an invalid framebuffer width. This commit fixed atomic crtc modesetting in a totally wrong way and introduced a local unnecessary ->enabled crtc state. This commit reverts the crctc _begin() and _enable() changes and simply adds drm_atomic_helper_commit_tail_rpm as helper. Reported-by: Tony McKahan <tonymckahan@gmail.com> Suggested-by: Daniel Vetter <daniel@ffwll.ch> Fixes: 2bcd3ecab773 ("drm/meson: Fixes for drm_crtc_vblank_on/off support") Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> [narmstrong: fixed blank line issue from checkpatch] Link: https://patchwork.freedesktop.org/patch/msgid/20190114153118.8024-1-narmstrong@baylibre.com
| | * | drm/meson: add missing of_node_putJulia Lawall2019-01-141-2/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add an of_node_put when the result of of_graph_get_remote_port_parent is not available. An of_node_put is also needed when meson_probe_remote completes. This was present at the recursive call, but not in the call from meson_drv_probe. The semantic match that finds this problem is as follows (http://coccinelle.lip6.fr): // <smpl> @r exists@ local idexpression e; expression x; @@ e = of_graph_get_remote_port_parent(...); ... when != x = e when != true e == NULL when != of_node_put(e) when != of_fwnode_handle(e) ( return e; | *return ...; ) // </smpl> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr> Acked-by: Neil Armstrong <narmstrong@baylibre.com> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com> Link: https://patchwork.freedesktop.org/patch/msgid/1547372691-28324-4-git-send-email-Julia.Lawall@lip6.fr
| | * | drm/virtio: drop prime import/export callbacksGerd Hoffmann2019-01-143-22/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Also set prime_handle_to_fd and prime_fd_to_handle to NULL, so drm will not advertive DRM_PRIME_CAP_{IMPORT,EXPORT} to userspace. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> Reviewed-by: Dave Airlie <airlied@redhat.com> Link: http://patchwork.freedesktop.org/patch/msgid/20190110111545.26768-1-kraxel@redhat.com
| | * | drm/qxl: drop prime import/export callbacksGerd Hoffmann2019-01-142-18/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Also set prime_handle_to_fd and prime_fd_to_handle to NULL, so drm will not advertive DRM_PRIME_CAP_{IMPORT,EXPORT} to userspace. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Reviewed-by: Dave Airlie <airlied@redhat.com> Link: http://patchwork.freedesktop.org/patch/msgid/20190110081750.11358-1-kraxel@redhat.com
| | * | drm/rockchip: add missing of_node_putJulia Lawall2019-01-131-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The device node iterators perform an of_node_get on each iteration, so a jump out of the loop requires an of_node_put. The semantic patch that fixes this problem is as follows (http://coccinelle.lip6.fr): // <smpl> @@ expression root,e; local idexpression child; iterator name for_each_child_of_node; @@ for_each_child_of_node(root, child) { ... when != of_node_put(child) when != e = child + of_node_put(child); ? break; ... } ... when != child // </smpl> Fixes: 1f0f01515172 ("drm/rockchip: Add support for Rockchip Soc RGB output interface") Cc: stable@vger.kernel.org Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr> [added fixes and cc-stable] Signed-off-by: Heiko Stuebner <heiko@sntech.de> Link: https://patchwork.freedesktop.org/patch/msgid/1547369264-24831-4-git-send-email-Julia.Lawall@lip6.fr
| * | | Merge tag 'drm-intel-fixes-2019-01-17' of ↵Dave Airlie2019-01-184-6/+29
| |\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://anongit.freedesktop.org/drm/drm-intel into drm-fixes drm/i915/gvt fixes for v5.0-rc3 "This contains one cmd parser failure fix to allow cmd access for one register, and fix region cleanup properly in vGPU destroy, and another fix for critical mmap size check mistake." Signed-off-by: Dave Airlie <airlied@redhat.com> From: Jani Nikula <jani.nikula@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/87ef9bfusc.fsf@intel.com
| | * \ \ Merge tag 'gvt-fixes-2018-01-17' of https://github.com/intel/gvt-linux into ↵Jani Nikula2019-01-174-6/+29
| | |\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | drm-intel-fixes gvt-fixes-2018-01-17 - Fix one register cmd parser failure (Colin) - Fix region cleanup for vGPU destroy (Henry) - Fix mmap size check (Zhenyu) Signed-off-by: Jani Nikula <jani.nikula@intel.com> From: Zhenyu Wang <zhenyuw@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190117074604.GI18272@zhen-hp.sh.intel.com
| | | * | | drm/i915/gvt: Fix mmap range checkZhenyu Wang2019-01-151-2/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is to fix missed mmap range check on vGPU bar2 region and only allow to map vGPU allocated GMADDR range, which means user space should support sparse mmap to get proper offset for mmap vGPU aperture. And this takes care of actual pgoff in mmap request as original code always does from beginning of vGPU aperture. Fixes: 659643f7d814 ("drm/i915/gvt/kvmgt: add vfio/mdev support to KVMGT") Cc: "Monroy, Rodrigo Axel" <rodrigo.axel.monroy@intel.com> Cc: "Orrala Contreras, Alfredo" <alfredo.orrala.contreras@intel.com> Cc: stable@vger.kernel.org # v4.10+ Reviewed-by: Hang Yuan <hang.yuan@intel.com> Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
| | | * | | drm/i915/gvt: free VFIO region space in vgpu detachHang Yuan2019-01-153-4/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | VFIO region space is allocated when one region is registered for one vgpu. So free the space when destroy the vgpu. Also change the parameter of detach_vgpu callback to use vgpu directly. Fixes: b851adeac0858c7d257b3 ("drm/i915/gvt: Add opregion support") Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com> Signed-off-by: Hang Yuan <hang.yuan@linux.intel.com> Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>