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kcov: avoid enable+disable interrupts if !in_task() 

kcov_remote_start() may need to allocate memory in the in_task() case
(otherwise per-CPU memory has been pre-allocated) and therefore requires
enabled interrupts.

The interrupts are enabled before checking if the allocation is required
so if no allocation is required then the interrupts are needlessly enabled
and disabled again.

Enable interrupts only if memory allocation is performed.

Link: https://lkml.kernel.org/r/20210923164741.1859522-5-bigeasy@linutronix.de
Link: https://lore.kernel.org/r/20210830172627.267989-5-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Marco Elver <elver@google.com>
Tested-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2021-11-08 18:35:37 -08:00 committed by Linus Torvalds
parent 741ddd4519
commit 22036abe17
1 changed files with 3 additions and 3 deletions
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6
kernel/kcov.c
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@ -869,19 +869,19 @@ void kcov_remote_start(u64 handle)
size = CONFIG_KCOV_IRQ_AREA_SIZE;
area = this_cpu_ptr(&kcov_percpu_data)->irq_area;
}
spin_unlock_irqrestore(&kcov_remote_lock, flags);
spin_unlock(&kcov_remote_lock);
/* Can only happen when in_task(). */
if (!area) {
local_irqrestore(flags);
area = vmalloc(size * sizeof(unsigned long));
if (!area) {
kcov_put(kcov);
return;
}
local_irq_save(flags);
}
local_irq_save(flags);
/* Reset coverage size. */
*(u64 *)area = 0;