From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
To: tglx@linutronix.de, peterz@infradead.org, tj@kernel.org,
oleg@redhat.com, paulmck@linux.vnet.ibm.com,
rusty@rustcorp.com.au, mingo@kernel.org,
akpm@linux-foundation.org, namhyung@kernel.org,
walken@google.com, vincent.guittot@linaro.org,
laijs@cn.fujitsu.com, David.Laight@aculab.com
Cc: linux-arch@vger.kernel.org, nikunj@linux.vnet.ibm.com,
zhong@linux.vnet.ibm.com, linux-pm@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
fweisbec@gmail.com, linux-kernel@vger.kernel.org,
rostedt@goodmis.org, xiaoguangrong@linux.vnet.ibm.com,
sbw@mit.edu, Ingo Molnar <mingo@redhat.com>,
wangyun@linux.vnet.ibm.com,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v3 11/45] sched/core: Use get/put_online_cpus_atomic() to prevent CPU offline
Date: Fri, 28 Jun 2013 01:24:25 +0530 [thread overview]
Message-ID: <20130627195425.29830.3829.stgit@srivatsabhat.in.ibm.com> (raw)
In-Reply-To: <20130627195136.29830.10445.stgit@srivatsabhat.in.ibm.com>
Once stop_machine() is gone from the CPU offline path, we won't be able
to depend on disabling preemption to prevent CPUs from going offline
from under us.
Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going
offline, while invoking from atomic context.
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---
kernel/sched/core.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9b1f2e5..9d870bf 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1160,11 +1160,11 @@ void kick_process(struct task_struct *p)
{
int cpu;
- preempt_disable();
+ get_online_cpus_atomic();
cpu = task_cpu(p);
if ((cpu != smp_processor_id()) && task_curr(p))
smp_send_reschedule(cpu);
- preempt_enable();
+ put_online_cpus_atomic();
}
EXPORT_SYMBOL_GPL(kick_process);
#endif /* CONFIG_SMP */
@@ -1172,6 +1172,9 @@ EXPORT_SYMBOL_GPL(kick_process);
#ifdef CONFIG_SMP
/*
* ->cpus_allowed is protected by both rq->lock and p->pi_lock
+ *
+ * Must be called within get/put_online_cpus_atomic(), to prevent
+ * CPUs from going offline from under us.
*/
static int select_fallback_rq(int cpu, struct task_struct *p)
{
@@ -1245,6 +1248,9 @@ out:
/*
* The caller (fork, wakeup) owns p->pi_lock, ->cpus_allowed is stable.
+ *
+ * Must be called within get/put_online_cpus_atomic(), to prevent
+ * CPUs from going offline from under us.
*/
static inline
int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
@@ -1489,6 +1495,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
unsigned long flags;
int cpu, success = 0;
+ get_online_cpus_atomic();
+
smp_wmb();
raw_spin_lock_irqsave(&p->pi_lock, flags);
if (!(p->state & state))
@@ -1531,6 +1539,7 @@ stat:
out:
raw_spin_unlock_irqrestore(&p->pi_lock, flags);
+ put_online_cpus_atomic();
return success;
}
@@ -1744,6 +1753,8 @@ void wake_up_new_task(struct task_struct *p)
unsigned long flags;
struct rq *rq;
+ get_online_cpus_atomic();
+
raw_spin_lock_irqsave(&p->pi_lock, flags);
#ifdef CONFIG_SMP
/*
@@ -1766,6 +1777,8 @@ void wake_up_new_task(struct task_struct *p)
p->sched_class->task_woken(rq, p);
#endif
task_rq_unlock(rq, p, &flags);
+
+ put_online_cpus_atomic();
}
#ifdef CONFIG_PREEMPT_NOTIFIERS
@@ -3879,6 +3892,8 @@ bool __sched yield_to(struct task_struct *p, bool preempt)
unsigned long flags;
int yielded = 0;
+ get_online_cpus_atomic();
+
local_irq_save(flags);
rq = this_rq();
@@ -3924,6 +3939,8 @@ out_unlock:
out_irq:
local_irq_restore(flags);
+ put_online_cpus_atomic();
+
if (yielded > 0)
schedule();
@@ -4324,9 +4341,11 @@ static int migration_cpu_stop(void *data)
* The original target cpu might have gone down and we might
* be on another cpu but it doesn't matter.
*/
+ get_online_cpus_atomic();
local_irq_disable();
__migrate_task(arg->task, raw_smp_processor_id(), arg->dest_cpu);
local_irq_enable();
+ put_online_cpus_atomic();
return 0;
}
next prev parent reply other threads:[~2013-06-27 19:57 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-27 19:52 [PATCH v3 00/45] CPU hotplug: stop_machine()-free CPU hotplug, part 1 Srivatsa S. Bhat
2013-06-27 19:52 ` [PATCH v3 01/45] CPU hotplug: Provide APIs to prevent CPU offline from atomic context Srivatsa S. Bhat
2013-06-27 19:52 ` [PATCH v3 02/45] CPU hotplug: Clarify the usage of different synchronization APIs Srivatsa S. Bhat
2013-06-27 19:52 ` [PATCH v3 03/45] Documentation, CPU hotplug: Recommend usage of get/put_online_cpus_atomic() Srivatsa S. Bhat
2013-06-27 19:53 ` [PATCH v3 04/45] CPU hotplug: Add infrastructure to check lacking hotplug synchronization Srivatsa S. Bhat
2013-06-27 19:53 ` [PATCH v3 05/45] CPU hotplug: Protect set_cpu_online() to avoid false-positives Srivatsa S. Bhat
2013-06-27 19:53 ` [PATCH v3 06/45] CPU hotplug: Sprinkle debugging checks to catch locking bugs Srivatsa S. Bhat
2013-06-27 19:53 ` [PATCH v3 07/45] CPU hotplug: Add _nocheck() variants of accessor functions Srivatsa S. Bhat
2013-06-27 19:53 ` [PATCH v3 08/45] CPU hotplug: Expose the new debug config option Srivatsa S. Bhat
2013-06-27 19:54 ` [PATCH v3 09/45] CPU hotplug: Convert preprocessor macros to static inline functions Srivatsa S. Bhat
2013-06-27 19:54 ` [PATCH v3 10/45] smp: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-07-02 5:32 ` Michael Wang
2013-07-02 8:25 ` Srivatsa S. Bhat
2013-07-02 8:47 ` Michael Wang
2013-07-02 9:51 ` Srivatsa S. Bhat
2013-07-02 10:08 ` Michael Wang
2013-06-27 19:54 ` Srivatsa S. Bhat [this message]
2013-06-27 19:54 ` [PATCH v3 12/45] migration: Use raw_spin_lock/unlock since interrupts are already disabled Srivatsa S. Bhat
2013-06-27 19:54 ` [PATCH v3 13/45] sched/fair: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-06-27 19:54 ` [PATCH v3 14/45] timer: " Srivatsa S. Bhat
2013-06-27 19:54 ` [PATCH v3 15/45] sched/rt: " Srivatsa S. Bhat
2013-06-27 19:55 ` [PATCH v3 16/45] rcu: Use cpu_is_offline_nocheck() to avoid false-positive warnings Srivatsa S. Bhat
2013-06-27 20:12 ` Paul E. McKenney
2013-06-27 19:55 ` [PATCH v3 17/45] tick-broadcast: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-06-27 19:55 ` [PATCH v3 18/45] time/clocksource: " Srivatsa S. Bhat
2013-06-27 19:56 ` [PATCH v3 19/45] softirq: " Srivatsa S. Bhat
2013-06-27 19:56 ` [PATCH v3 20/45] irq: " Srivatsa S. Bhat
2013-06-27 19:56 ` [PATCH v3 21/45] net: " Srivatsa S. Bhat
2013-06-27 19:56 ` [PATCH v3 22/45] block: " Srivatsa S. Bhat
2013-06-27 19:56 ` [PATCH v3 23/45] percpu_counter: Use _nocheck version of for_each_online_cpu() Srivatsa S. Bhat
2013-06-27 19:56 ` [PATCH v3 24/45] infiniband: ehca: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-06-27 19:56 ` [PATCH v3 25/45] [SCSI] fcoe: " Srivatsa S. Bhat
2013-06-27 19:57 ` [PATCH v3 26/45] staging/octeon: " Srivatsa S. Bhat
2013-06-27 19:57 ` [PATCH v3 27/45] x86: " Srivatsa S. Bhat
2013-06-27 19:57 ` [PATCH v3 28/45] perf/x86: " Srivatsa S. Bhat
2013-06-27 19:57 ` [PATCH v3 29/45] KVM: " Srivatsa S. Bhat
2013-06-27 19:57 ` [PATCH v3 30/45] x86/xen: " Srivatsa S. Bhat
2013-06-27 19:57 ` [PATCH v3 31/45] alpha/smp: " Srivatsa S. Bhat
2013-06-27 19:58 ` [PATCH v3 32/45] blackfin/smp: " Srivatsa S. Bhat
2013-06-27 19:58 ` [PATCH v3 33/45] cris/smp: " Srivatsa S. Bhat
2013-06-27 19:58 ` [PATCH v3 34/45] hexagon/smp: " Srivatsa S. Bhat
2013-06-27 19:58 ` [PATCH v3 35/45] ia64: irq, perfmon: " Srivatsa S. Bhat
2013-06-27 19:59 ` [PATCH v3 36/45] ia64: smp, tlb: " Srivatsa S. Bhat
2013-06-27 19:59 ` [PATCH v3 37/45] m32r: " Srivatsa S. Bhat
2013-06-27 19:59 ` [PATCH v3 38/45] MIPS: " Srivatsa S. Bhat
2013-06-27 19:59 ` [PATCH v3 39/45] mn10300: " Srivatsa S. Bhat
2013-06-27 19:59 ` [PATCH v3 40/45] powerpc, irq: Use GFP_ATOMIC allocations in atomic context Srivatsa S. Bhat
2013-06-27 20:00 ` [PATCH v3 41/45] powerpc: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-06-27 20:00 ` [PATCH v3 42/45] powerpc: Use get/put_online_cpus_atomic() to avoid false-positive warning Srivatsa S. Bhat
2013-06-27 20:00 ` [PATCH v3 43/45] sh: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-06-27 20:00 ` [PATCH v3 44/45] sparc: " Srivatsa S. Bhat
2013-06-27 20:00 ` [PATCH v3 45/45] tile: " Srivatsa S. Bhat
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