From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>, John Kacur <jkacur@redhat.com>
Subject: [PATCH RT 7/8] stomp_machine: Use mutex_trylock when called from inactive cpu
Date: Wed, 10 Oct 2012 09:34:13 -0400 [thread overview]
Message-ID: <20121010133523.959048417@goodmis.org> (raw)
In-Reply-To: 20121010133406.053812290@goodmis.org
[-- Attachment #1: 0007-stomp_machine-Use-mutex_trylock-when-called-from-ina.patch --]
[-- Type: text/plain, Size: 2153 bytes --]
From: Thomas Gleixner <tglx@linutronix.de>
If the stop machinery is called from inactive CPU we cannot use
mutex_lock, because some other stomp machine invokation might be in
progress and the mutex can be contended. We cannot schedule from this
context, so trylock and loop.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable-rt@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/stop_machine.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 561ba3a..e98c70b 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -158,7 +158,7 @@ static DEFINE_PER_CPU(struct cpu_stop_work, stop_cpus_work);
static void queue_stop_cpus_work(const struct cpumask *cpumask,
cpu_stop_fn_t fn, void *arg,
- struct cpu_stop_done *done)
+ struct cpu_stop_done *done, bool inactive)
{
struct cpu_stop_work *work;
unsigned int cpu;
@@ -175,7 +175,12 @@ static void queue_stop_cpus_work(const struct cpumask *cpumask,
* Make sure that all work is queued on all cpus before we
* any of the cpus can execute it.
*/
- mutex_lock(&stopper_lock);
+ if (!inactive) {
+ mutex_lock(&stopper_lock);
+ } else {
+ while (!mutex_trylock(&stopper_lock))
+ cpu_relax();
+ }
for_each_cpu(cpu, cpumask)
cpu_stop_queue_work(&per_cpu(cpu_stopper, cpu),
&per_cpu(stop_cpus_work, cpu));
@@ -188,7 +193,7 @@ static int __stop_cpus(const struct cpumask *cpumask,
struct cpu_stop_done done;
cpu_stop_init_done(&done, cpumask_weight(cpumask));
- queue_stop_cpus_work(cpumask, fn, arg, &done);
+ queue_stop_cpus_work(cpumask, fn, arg, &done, false);
wait_for_stop_done(&done);
return done.executed ? done.ret : -ENOENT;
}
@@ -601,7 +606,7 @@ int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data,
set_state(&smdata, STOPMACHINE_PREPARE);
cpu_stop_init_done(&done, num_active_cpus());
queue_stop_cpus_work(cpu_active_mask, stop_machine_cpu_stop, &smdata,
- &done);
+ &done, true);
ret = stop_machine_cpu_stop(&smdata);
/* Busy wait for completion. */
--
1.7.10.4
next prev parent reply other threads:[~2012-10-10 13:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-10 13:34 [PATCH RT 0/8] [ANNOUNCE] 3.4.13-rt22-rc1 stable review Steven Rostedt
2012-10-10 13:34 ` [PATCH RT 1/8] random: Make it work on rt Steven Rostedt
2012-10-10 13:34 ` [PATCH RT 2/8] softirq: Init softirq local lock after per cpu section is set up Steven Rostedt
2012-10-10 13:34 ` [PATCH RT 3/8] mm: slab: Fix potential deadlock Steven Rostedt
2012-10-10 13:34 ` [PATCH RT 4/8] mm: page_alloc: Use local_lock_on() instead of plain spinlock Steven Rostedt
2012-10-10 13:34 ` [PATCH RT 5/8] rt: rwsem/rwlock: lockdep annotations Steven Rostedt
2012-10-10 13:34 ` [PATCH RT 6/8] sched: Better debug output for might sleep Steven Rostedt
2012-10-10 13:34 ` Steven Rostedt [this message]
2012-10-10 13:34 ` [PATCH RT 8/8] Linux 3.4.13-rt22-rc1 Steven Rostedt
-- strict thread matches above, loose matches on Subject: below --
2012-10-12 1:20 [PATCH RT 0/8] [ANNOUNCE] 3.2.31-rt47-rc1 stable review Steven Rostedt
2012-10-12 1:20 ` [PATCH RT 7/8] stomp_machine: Use mutex_trylock when called from inactive cpu Steven Rostedt
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