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2011-05-17Freezer: Use SMP barriersMike Frysinger
The freezer processes are dealing with multiple threads running simultaneously, and on a UP system, the memory reads/writes do not need barriers to keep things in sync. These are only needed on SMP systems, so use SMP barriers instead. Signed-off-by: Mike Frysinger <vapier@gentoo.org> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-17PM / Suspend: Do not ignore error codes returned by suspend_enter()MyungJoo Ham
The current implementation of suspend-to-RAM returns 0 if there is an error from suspend_enter(), because suspend_devices_and_enter() ignores the return value from suspend_enter(). This patch addresses this issue and properly keep the error return from suspend_enter() and let suspend_devices_and_enter relay the error return. Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-05-17Merge branch 'timers-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: tick: Clear broadcast active bit when switching to oneshot rtc: mc13xxx: Don't call rtc_device_register while holding lock rtc: rp5c01: Initialize drvdata before registering device rtc: pcap: Initialize drvdata before registering device rtc: msm6242: Initialize drvdata before registering device rtc: max8998: Initialize drvdata before registering device rtc: max8925: Initialize drvdata before registering device rtc: m41t80: Initialize clientdata before registering device rtc: ds1286: Initialize drvdata before registering device rtc: ep93xx: Initialize drvdata before registering device rtc: davinci: Initialize drvdata before registering device rtc: mxc: Initialize drvdata before registering device clocksource: Install completely before selecting
2011-05-16tick: Clear broadcast active bit when switching to oneshotThomas Gleixner
The first cpu which switches from periodic to oneshot mode switches also the broadcast device into oneshot mode. The broadcast device serves as a backup for per cpu timers which stop in deeper C-states. To avoid starvation of the cpus which might be in idle and depend on broadcast mode it marks the other cpus as broadcast active and sets the brodcast expiry value of those cpus to the next tick. The oneshot mode broadcast bit for the other cpus is sticky and gets only cleared when those cpus exit idle. If a cpu was not idle while the bit got set in consequence the bit prevents that the broadcast device is armed on behalf of that cpu when it enters idle for the first time after it switched to oneshot mode. In most cases that goes unnoticed as one of the other cpus has usually a timer pending which keeps the broadcast device armed with a short timeout. Now if the only cpu which has a short timer active has the bit set then the broadcast device will not be armed on behalf of that cpu and will fire way after the expected timer expiry. In the case of Christians bug report it took ~145 seconds which is about half of the wrap around time of HPET (the limit for that device) due to the fact that all other cpus had no timers armed which expired before the 145 seconds timeframe. The solution is simply to clear the broadcast active bit unconditionally when a cpu switches to oneshot mode after the first cpu switched the broadcast device over. It's not idle at that point otherwise it would not be executing that code. [ I fundamentally hate that broadcast crap. Why the heck thought some folks that when going into deep idle it's a brilliant concept to switch off the last device which brings the cpu back from that state? ] Thanks to Christian for providing all the valuable debug information! Reported-and-tested-by: Christian Hoffmann <email@christianhoffmann.info> Cc: John Stultz <johnstul@us.ibm.com> Link: http://lkml.kernel.org/r/%3Calpine.LFD.2.02.1105161105170.3078%40ionos%3E Cc: stable@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-05-16sched: Fix and optimise calculation of the weight-inverseStephan Baerwolf
If the inverse loadweight should be zero, function "calc_delta_mine" calculates the inverse of "lw->weight" (in 32bit integer ops). This calculation is actually a little bit impure (because it is inverting something around "lw-weight"+1), especially when "lw->weight" becomes smaller. The correct inverse would be 1/lw->weight multiplied by "WMULT_CONST" for fixcomma-scaling it into integers. (So WMULT_CONST/lw->weight ...) The old, impure algorithm took two divisions for inverting lw->weight, the new, more exact one only takes one and an additional unlikely-if. Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-0pz0wnyalr4tk4ln11xwumdx@git.kernel.org [ This could explain some aritmetical issues for small shares but nothing concrete has been reported yet so we are not confident enough to queue this up in sched/urgent and for -stable backport. But if anyone finds this commit and sees it to fix some badness then we can certainly change our mind! ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-16sched: Avoid going ahead if ->cpus_allowed is not changedYong Zhang
If cpumask_equal(&p->cpus_allowed, new_mask) is true, seems there is no reason to prevent set_cpus_allowed_ptr() return directly. Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Acked-by: Hillf Danton <dhillf@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110509140705.GA2219@zhy Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-16sched, rt: Update rq clock when unthrottling of an otherwise idle CPUMike Galbraith
If an RT task is awakened while it's rt_rq is throttled, the time between wakeup/enqueue and unthrottle/selection may be accounted as rt_time if the CPU is idle. Set rq->skip_clock_update negative upon throttle release to tell put_prev_task() that we need a clock update. Reported-by: Thomas Giesel <skoe@directbox.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1304059010.7472.1.camel@marge.simson.net Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-16sched: Fix rt_rq runtime leakage bugCheng Xu
This patch is to fix the real-time scheduler bug reported at: https://lkml.org/lkml/2011/4/26/13 That is, when running multiple real-time threads on every logical CPUs and then turning off one CPU, the kernel will bug at function __disable_runtime(). Function __disable_runtime() bugs and reports leakage of rt_rq runtime. The root cause is __disable_runtime() assumes it iterates through all the existing rt_rq's while walking rq->leaf_rt_rq_list, which actually contains only runnable rt_rq's. This problem also applies to __enable_runtime() and print_rt_stats(). The patch is based on above analysis, appears to fix the problem, but is only lightly tested. Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Cheng Xu <chengxu@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4DCE1F12.6040609@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-13Cache user_ns in struct credSerge E. Hallyn
If !CONFIG_USERNS, have current_user_ns() defined to (&init_user_ns). Get rid of _current_user_ns. This requires nsown_capable() to be defined in capability.c rather than as static inline in capability.h, so do that. Request_key needs init_user_ns defined at current_user_ns if !CONFIG_USERNS, so forward-declare that in cred.h if !CONFIG_USERNS at current_user_ns() define. Compile-tested with and without CONFIG_USERNS. Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> [ This makes a huge performance difference for acl_permission_check(), up to 30%. And that is one of the hottest kernel functions for loads that are pathname-lookup heavy. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-12sched: Remove unused parameters from sched_fork() and wake_up_new_task()Samir Bellabes
sched_fork() and wake_up_new_task() are defined with a parameter 'unsigned long clone_flags', which is unused. This patch removes the parameters. Signed-off-by: Samir Bellabes <sam@synack.fr> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1305130685-1047-1-git-send-email-sam@synack.fr Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-12Merge commit 'v2.6.39-rc7' into sched/coreIngo Molnar
2011-05-11PM: Remove sysdev suspend, resume and shutdown operationsRafael J. Wysocki
Since suspend, resume and shutdown operations in struct sysdev_class and struct sysdev_driver are not used any more, remove them. Also drop sysdev_suspend(), sysdev_resume() and sysdev_shutdown() used for executing those operations and modify all of their users accordingly. This reduces kernel code size quite a bit and reduces its complexity. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-05-11PM / Hibernate: Fix ioctl SNAPSHOT_S2RAMRafael J. Wysocki
The SNAPSHOT_S2RAM ioctl used for implementing the feature allowing one to suspend to RAM after creating a hibernation image is currently broken, because it doesn't clear the "ready" flag in the struct snapshot_data object handled by it. As a result, the SNAPSHOT_UNFREEZE doesn't work correctly after SNAPSHOT_S2RAM has returned and the user space hibernate task cannot thaw the other processes as appropriate. Make SNAPSHOT_S2RAM clear data->ready to fix this problem. Tested-by: Alexandre Felipe Muller de Souza <alexandrefm@mandriva.com.br> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: stable@kernel.org
2011-05-11PM / Hibernate: Make snapshot_release() restore GFP maskRafael J. Wysocki
If the process using the hibernate user space interface closes /dev/snapshot after creating a hibernation image without thawing tasks, snapshot_release() should call pm_restore_gfp_mask() to restore the GFP mask used before the creation of the image. Make that happen. Tested-by: Alexandre Felipe Muller de Souza <alexandrefm@mandriva.com.br> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: stable@kernel.org
2011-05-11PM: Fix warning in pm_restrict_gfp_mask() during SNAPSHOT_S2RAM ioctlRafael J. Wysocki
A warning is printed by pm_restrict_gfp_mask() while the SNAPSHOT_S2RAM ioctl is being executed after creating a hibernation image, because pm_restrict_gfp_mask() has been called once already before the image creation and suspend_devices_and_enter() calls it once again. This happens after commit 452aa6999e6703ffbddd7f6ea124d3 (mm/pm: force GFP_NOIO during suspend/hibernation and resume). To avoid this issue, move pm_restrict_gfp_mask() and pm_restore_gfp_mask() from suspend_devices_and_enter() to its caller in kernel/power/suspend.c. Reported-by: Alexandre Felipe Muller de Souza <alexandrefm@mandriva.com.br> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: stable@kernel.org
2011-05-10Merge commit 'v2.6.39-rc7' into perf/coreIngo Molnar
Merge reason: pull in the latest fixes. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-07perf,rcu: convert call_rcu(swevent_hlist_release_rcu) to kfree_rcu()Lai Jiangshan
The rcu callback swevent_hlist_release_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(swevent_hlist_release_rcu). Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-07perf,rcu: convert call_rcu(free_ctx) to kfree_rcu()Lai Jiangshan
The rcu callback free_ctx() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(free_ctx). Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-07cgroup,rcu: convert call_rcu(__free_css_id_cb) to kfree_rcu()Lai Jiangshan
The rcu callback __free_css_id_cb() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(__free_css_id_cb). Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Paul Menage <menage@google.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-07cgroup,rcu: convert call_rcu(free_cgroup_rcu) to kfree_rcu()Lai Jiangshan
The rcu callback free_cgroup_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(free_cgroup_rcu). Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Paul Menage <menage@google.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-07cgroup,rcu: convert call_rcu(free_css_set_rcu) to kfree_rcu()Lai Jiangshan
The rcu callback free_css_set_rcu() just calls a kfree(), so we use kfree_rcu() instead of the call_rcu(free_css_set_rcu). Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Paul Menage <menage@google.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-07rcu: permit rcu_read_unlock() to be called while holding runqueue locksPaul E. McKenney
Avoid calling into the scheduler while holding core RCU locks. This allows rcu_read_unlock() to be called while holding the runqueue locks, but only as long as there was no chance of the RCU read-side critical section having been preempted. (Otherwise, if RCU priority boosting is enabled, rcu_read_unlock() might call into the scheduler in order to unboost itself, which might allows self-deadlock on the runqueue locks within the scheduler.) Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-07Merge branch 'perf-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: perf tools: Makefile: Use gcc to determine ARCH perf events, x86: Fix Intel Nehalem and Westmere last level cache event definitions hw_breakpoints, powerpc: Fix CONFIG_HAVE_HW_BREAKPOINT off-case in ptrace_set_debugreg() sh, hw_breakpoints: Fix racy access to ptrace breakpoints arm, hw_breakpoints: Fix racy access to ptrace breakpoints powerpc, hw_breakpoints: Fix racy access to ptrace breakpoints x86, hw_breakpoints: Fix racy access to ptrace breakpoints ptrace: Prepare to fix racy accesses on task breakpoints
2011-05-06reboot: disable usermodehelper to prevent fs accessKay Sievers
In case CONFIG_UEVENT_HELPER_PATH is not set to "", which it should be on every system, the kernel forks processes during shutdown, which try to access the rootfs, even when the binary does not exist. It causes exceptions and long delays in the disk driver, which gets read requests at the time it tries to shut down the disk. This patch disables all kernel-forked processes during reboot to allow a clean poweroff. Cc: Tejun Heo <htejun@gmail.com> Tested-By: Anton Guda <atu@dmeti.dp.ua> Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-05-06Regression: partial revert "tracing: Remove lock_depth from event entry"Arjan van de Ven
This partially reverts commit e6e1e2593592a8f6f6380496655d8c6f67431266. That commit changed the structure layout of the trace structure, which in turn broke PowerTOP (1.9x generation) quite badly. I appreciate not wanting to expose the variable in question, and PowerTOP was not using it, so I've replaced the variable with just a padding field - that way if in the future a new field is needed it can just use this padding field. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-06sched: Shorten the construction of the span cpu mask of sched domainHillf Danton
For a given node, when constructing the cpumask for its sched_domain to span, if there is no best node available after searching, further efforts could be saved, based on small change in the return value of find_next_best_node(). Signed-off-by: Hillf Danton <dhillf@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Yong Zhang <yong.zhang0@gmail.com> Link: http://lkml.kernel.org/r/BANLkTi%3DqPWxRAa6%2BdT3ohEP6Z%3D0v%2Be4EXA@mail.gmail.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-06sched: Wrap the 'cfs_rq->nr_spread_over' field with CONFIG_SCHED_DEBUGRakib Mullick
cfs_rq->nr_spread_over is only used when CONFIG_SCHED_DEBUG is set. So wrap it with CONFIG_SCHED_DEBUG. Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1304528026.15681.3.camel@localhost.localdomain Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-05-05rcu: provide rcu_virt_note_context_switch() function.Gleb Natapov
Provide rcu_virt_note_context_switch() for vitalization use to note quiescent state during guest entry. Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05rcu: get rid of signed overflow in check_cpu_stall()Paul E. McKenney
Signed integer overflow is undefined by the C standard, so move calculations to unsigned. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05rcu: optimize rcutinyEric Dumazet
rcu_sched_qs() currently calls local_irq_save()/local_irq_restore() up to three times. Remove irq masking from rcu_qsctr_help() / invoke_rcu_kthread() and do it once in rcu_sched_qs() / rcu_bh_qs() This generates smaller code as well. text data bss dec hex filename 2314 156 24 2494 9be kernel/rcutiny.old.o 2250 156 24 2430 97e kernel/rcutiny.new.o Fix an outdated comment for rcu_qsctr_help() Move invoke_rcu_kthread() definition before its use. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05rcu: prevent call_rcu() from diving into rcu core if irqs disabledPaul E. McKenney
This commit marks a first step towards making call_rcu() have real-time behavior. If irqs are disabled, don't dive into the RCU core. Later on, this new early exit will wake up the per-CPU kthread, which first must be modified to handle the cases involving callback storms. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05rcu: further lower priority in rcu_yield()Paul E. McKenney
Although rcu_yield() dropped from real-time to normal priority, there is always the possibility that the competing tasks have been niced. So nice to 19 in rcu_yield() to help ensure that other tasks have a better chance of running. 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>
2011-05-05rcu: introduce kfree_rcu()Lai Jiangshan
Many rcu callbacks functions just call kfree() on the base structure. These functions are trivial, but their size adds up, and furthermore when they are used in a kernel module, that module must invoke the high-latency rcu_barrier() function at module-unload time. The kfree_rcu() function introduced by this commit addresses this issue. Rather than encoding a function address in the embedded rcu_head structure, kfree_rcu() instead encodes the offset of the rcu_head structure within the base structure. Because the functions are not allowed in the low-order 4096 bytes of kernel virtual memory, offsets up to 4095 bytes can be accommodated. If the offset is larger than 4095 bytes, a compile-time error will be generated in __kfree_rcu(). If this error is triggered, you can either fall back to use of call_rcu() or rearrange the structure to position the rcu_head structure into the first 4096 bytes. Note that the allowable offset might decrease in the future, for example, to allow something like kmem_cache_free_rcu(). The new kfree_rcu() function can replace code as follows: call_rcu(&p->rcu, simple_kfree_callback); where "simple_kfree_callback()" might be defined as follows: void simple_kfree_callback(struct rcu_head *p) { struct foo *q = container_of(p, struct foo, rcu); kfree(q); } with the following: kfree_rcu(&p->rcu, rcu); Note that the "rcu" is the name of a field in the structure being freed. The reason for using this rather than passing in a pointer to the base structure is that the above approach allows better type checking. This commit is based on earlier work by Lai Jiangshan and Manfred Spraul: Lai's V1 patch: http://lkml.org/lkml/2008/9/18/1 Manfred's patch: http://lkml.org/lkml/2009/1/2/115 Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: David Howells <dhowells@redhat.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05rcu: fix spellingPaul E. McKenney
The "preemptible" spelling is preferable. May as well fix it. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05rcu: call __rcu_read_unlock() in exit_rcu for tree RCULai Jiangshan
Using __rcu_read_lock() in place of rcu_read_lock() leaves any debug state as it really should be, namely with the lock still held. 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>
2011-05-05rcu: Converge TINY_RCU expedited and normal boostingPaul E. McKenney
This applies a trick from TREE_RCU boosting to TINY_RCU, eliminating code and adding comments. The key point is that it is possible for the booster thread itself to work out whether there is a normal or expedited boost required based solely on local information. There is therefore no need for boost initiation to know or care what type of boosting is required. In addition, when boosting is complete for a given grace period, then by definition there cannot be any more boosting for that grace period. This allows eliminating yet more state and statistics. 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>
2011-05-05rcu: remove useless ->boosted_this_gp fieldPaul E. McKenney
The ->boosted_this_gp field is a holdover from an earlier design that was to carry out multiple boost operations in parallel. It is not required by the current design, which boosts one task at a time. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05rcu: code cleanups in TINY_RCU priority boosting.Paul E. McKenney
Extraneous semicolon, bad comment, and fold INIT_LIST_HEAD() into list_del() to get list_del_init(). 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>
2011-05-05rcu: Switch to this_cpu() primitivesPaul E. McKenney
This removes a couple of lines from invoke_rcu_cpu_kthread(), improving readability. Reported-by: Christoph Lameter <cl@linux.com> 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>
2011-05-05rcu: Use WARN_ON_ONCE for DEBUG_OBJECTS_RCU_HEAD warningsPaul E. McKenney
Avoid additional multiple-warning confusion in memory-corruption scenarios. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05rcu: mark rcutorture boosting callback as being on-stackPaul E. McKenney
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>
2011-05-05rcu: Enable DEBUG_OBJECTS_RCU_HEAD from !PREEMPTMathieu Desnoyers
The prohibition of DEBUG_OBJECTS_RCU_HEAD from !PREEMPT was due to the fixup actions. So just produce a warning from !PREEMPT. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2011-05-05rcu: Add forward-progress diagnostic for per-CPU kthreadsPaul E. McKenney
Increment a per-CPU counter on each pass through rcu_cpu_kthread()'s service loop, and add it to the rcudata trace output. 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>
2011-05-05rcu: add grace-period age and more kthread state to tracingPaul E. McKenney
This commit adds the age in jiffies of the current grace period along with the duration in jiffies of the longest grace period since boot to the rcu/rcugp debugfs file. It also adds an additional "O" state to kthread tracing to differentiate between the kthread waiting due to having nothing to do on the one hand and waiting due to being on the wrong CPU on the other hand. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05rcu: fix tracing bug thinko on boost-balk attributionPaul E. McKenney
The rcu_initiate_boost_trace() function mis-attributed refusals to initiate RCU priority boosting that were in fact due to its not yet being time to boost. This patch fixes the faulty comparison. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-05-05rcu: make rcutorture version numbers available through debugfsPaul E. McKenney
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>
2011-05-05rcu: add tracing for RCU's kthread run states.Paul E. McKenney
Add tracing to help debugging situations when RCU's kthreads are not running but are supposed to be. 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>
2011-05-05rcu: add callback-queue information to rcudata outputPaul E. McKenney
This commit adds an indication of the state of the callback queue using a string of four characters following the "ql=" integer queue length. The first character is "N" if there are callbacks that have been queued that are not yet ready to be handled by the next grace period, or "." otherwise. The second character is "R" if there are callbacks queued that are ready to be handled by the next grace period, or "." otherwise. The third character is "W" if there are callbacks waiting for the current grace period, or "." otherwise. Finally, the fourth character is "D" if there are callbacks that have been handled by a prior grace period and are waiting to be invoked, or ".". Note that callbacks that are in the process of being invoked are not shown. These callbacks would have been removed from the rcu_data structure's list by rcu_do_batch() prior to being executed. (These callbacks are also not reflected in the "ql=" total, FWIW.) Also, document the new callback-queue trace information. 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>
2011-05-05rcu: Add boosting to TREE_PREEMPT_RCU tracingPaul E. McKenney
Includes total number of tasks boosted, number boosted on behalf of each of normal and expedited grace periods, and statistics on attempts to initiate boosting that failed for various reasons. 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>
2011-05-05rcu: eliminate unused boosting statisticsPaul E. McKenney
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>