Commit 22036abe authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Linus Torvalds
Browse files

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: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: default avatarDmitry Vyukov <dvyukov@google.com>
Acked-by: default avatarMarco Elver <elver@google.com>
Tested-by: default avatarMarco Elver <elver@google.com>
Reviewed-by: default avatarAndrey Konovalov <andreyknvl@gmail.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 741ddd45

kernel/kcov.c

+3 −3
Original line number Diff line number Diff line
@@ -869,18 +869,18 @@ 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);

	}



	/* Reset coverage size. */

	*(u64 *)area = 0;