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* rcu: Make rcu/tiny_plugin.h explicitly non-modularPaul Gortmaker2016-02-231-13/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | The Kconfig currently controlling compilation of this code is: init/Kconfig:config TINY_RCU init/Kconfig: bool ...meaning that it currently is not being built as a module by anyone. Lets remove the modular code that is essentially orphaned, so that when reading the code there is no doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering remains unchanged with this commit. We could consider moving this to an earlier initcall (subsys?) if desired. We also delete the MODULE_LICENSE tag etc. since all that information is already contained at the top of the file in the comments. Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()Paul E. McKenney2015-05-271-5/+7
| | | | | | | | This commit moves from the old ACCESS_ONCE() API to the new READ_ONCE() and WRITE_ONCE() APIs. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Updated to include kernel/torture.c as suggested by Jason Low. ]
*-. Merge branches 'doc.2015.01.07a', 'fixes.2015.01.15a', ↵Paul E. McKenney2015-01-151-5/+4
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'preempt.2015.01.06a', 'srcu.2015.01.06a', 'stall.2015.01.16a' and 'torture.2015.01.11a' into HEAD doc.2015.01.07a: Documentation updates. fixes.2015.01.15a: Miscellaneous fixes. preempt.2015.01.06a: Changes to handling of lists of preempted tasks. srcu.2015.01.06a: SRCU updates. stall.2015.01.16a: RCU CPU stall-warning updates and fixes. torture.2015.01.11a: RCU torture-test updates and fixes.
| | * rcu: Fix RCU CPU stall detection in tiny implementationMiroslav Benes2015-01-151-4/+3
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | The tiny RCU CPU stall detection depends on *rcp->curtail not being NULL. It is however a tail pointer and thus NULL by definition. Instead we should check rcp->rcucblist for the presence of pending callbacks which need to be processed. With this fix INFO about the stall is printed and jiffies_stall (jiffies at next stall) correctly updated. Note that the check for pending callback is necessary to avoid spurious warnings if there are no pendings callbacks. Signed-off-by: Miroslav Benes <mbenes@suse.cz> [ paulmck: Fused identical "if" statements, ported to -rcu. ] Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| * tiny_rcu: Directly force QS when call_rcu_[bh|sched]() on idle_taskLai Jiangshan2015-01-061-1/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For RCU in UP, context-switch = QS = GP, thus we can force a context-switch when any call_rcu_[bh|sched]() is happened on idle_task. After doing so, rcu_idle/irq_enter/exit() are useless, so we can simply make these functions empty. More important, this change does not change the functionality logically. Note: raise_softirq(RCU_SOFTIRQ)/rcu_sched_qs() in rcu_idle_enter() and outmost rcu_irq_exit() will have to wake up the ksoftirqd (due to in_interrupt() == 0). Before this patch After this patch: call_rcu_sched() in idle; call_rcu_sched() in idle set resched do other stuffs; do other stuffs outmost rcu_irq_exit() outmost rcu_irq_exit() (empty function) (or rcu_idle_enter()) (or rcu_idle_enter(), also empty function) start to resched. (see above) rcu_sched_qs() rcu_sched_qs() QS,and GP and advance cb QS,and GP and advance cb wake up the ksoftirqd wake up the ksoftirqd set resched resched to ksoftirqd (or other) resched to ksoftirqd (or other) These two code patches are almost the same. Size changed after patched: size kernel/rcu/tiny-old.o kernel/rcu/tiny-patched.o text data bss dec hex filename 3449 206 8 3663 e4f kernel/rcu/tiny-old.o 2406 144 8 2558 9fe kernel/rcu/tiny-patched.o Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Protect uses of ->jiffies_stall with ACCESS_ONCE()Himangi Saraogi2014-04-291-4/+4
| | | | | | | | | | | | | | | | | | | | Some of the accesses to the rcu_state structure's ->jiffies_stall field are unprotected. This patch protects them with ACCESS_ONCE(). The following coccinelle script was used to acheive this: /* coccinelle script to protect uses of ->jiffies_stall with ACCESS_ONCE() */ @@ identifier a; @@ ( ACCESS_ONCE(a->jiffies_stall) | - a->jiffies_stall + ACCESS_ONCE(a->jiffies_stall) ) Signed-off-by: Himangi Saraogi <himangi774@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: Stop tracking FSF's postal addressPaul E. McKenney2014-02-171-2/+2
| | | | | | | | | | | | All of the RCU source files have the usual GPL header, which contains a long-obsolete postal address for FSF. To avoid the need to track the FSF office's movements, this commit substitutes the URL where GPL may be found. Reported-by: Greg KH <gregkh@linuxfoundation.org> Reported-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: Move RCU-related source code to kernel/rcu directoryPaul E. McKenney2013-10-151-0/+174
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Ingo Molnar <mingo@kernel.org>
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