Commit-ID: accaf6ea3db6f5fb997f096b6eefd5431d03f7e5 Gitweb: http://git.kernel.org/tip/accaf6ea3db6f5fb997f096b6eefd5431d03f7e5 Author: Oleg Nesterov <[email protected]> AuthorDate: Sun, 15 Nov 2015 20:33:32 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 23 Nov 2015 09:48:20 +0100
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 <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Tejun Heo <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Milos Vyletel <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Prarit Bhargava <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/stop_machine.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 7ff7ace..6110119 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; } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
