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| author | Oleg Nesterov <oleg@redhat.com> | 2015-11-15 20:33:32 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-11-23 09:48:20 +0100 |
| commit | accaf6ea3db6f5fb997f096b6eefd5431d03f7e5 (patch) | |
| tree | 3e17684822d4d0e9685ef0d598c2fa55ab88495e /kernel | |
| parent | dd2e3121e3cb16d03a6e3f2db48f260f046f39c2 (diff) | |
| download | linux-accaf6ea3db6f5fb997f096b6eefd5431d03f7e5.tar.gz linux-accaf6ea3db6f5fb997f096b6eefd5431d03f7e5.tar.bz2 linux-accaf6ea3db6f5fb997f096b6eefd5431d03f7e5.zip | |
stop_machine: Clean up the usage of the preemption counter in cpu_stopper_thread()
1. Change this code to use preempt_count_inc/preempt_count_dec; this way
it works even if CONFIG_PREEMPT_COUNT=n, and we avoid the unnecessary
__preempt_schedule() check (stop_sched_class is not preemptible).
And this makes clear that we only want to make preempt_count() != 0
for __might_sleep() / schedule_debug().
2. Change WARN_ONCE() to use %pf to print the function name and remove
kallsyms_lookup/ksym_buf.
3. Move "int ret" into the "if (work)" block, this looks more consistent.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Milos Vyletel <milos@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20151115193332.GA8281@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/stop_machine.c | 15 |
1 files changed, 5 insertions, 10 deletions
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 7ff7acee2c76..61101193967e 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -435,7 +435,6 @@ static void cpu_stopper_thread(unsigned int cpu) { struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu); struct cpu_stop_work *work; - int ret; repeat: work = NULL; @@ -451,23 +450,19 @@ repeat: cpu_stop_fn_t fn = work->fn; void *arg = work->arg; struct cpu_stop_done *done = work->done; - char ksym_buf[KSYM_NAME_LEN] __maybe_unused; + int ret; - /* cpu stop callbacks are not allowed to sleep */ - preempt_disable(); + /* cpu stop callbacks must not sleep, make in_atomic() == T */ + preempt_count_inc(); ret = fn(arg); if (done) { if (ret) done->ret = ret; cpu_stop_signal_done(done); } - /* restore preemption and check it's still balanced */ - preempt_enable(); + preempt_count_dec(); WARN_ONCE(preempt_count(), - "cpu_stop: %s(%p) leaked preempt count\n", - kallsyms_lookup((unsigned long)fn, NULL, NULL, NULL, - ksym_buf), arg); - + "cpu_stop: %pf(%p) leaked preempt count\n", fn, arg); goto repeat; } } |