From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxxx Link: https://lore.kernel.org/r/20210830172627.267989-5-bigeasy@xxxxxxxxxxxxx Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Acked-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Acked-by: Marco Elver <elver@xxxxxxxxxx> Tested-by: Marco Elver <elver@xxxxxxxxxx> Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx> Cc: Clark Williams <williams@xxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/kcov.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/kcov.c~kcov-avoid-enabledisable-interrupts-if-in_task +++ a/kernel/kcov.c @@ -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; _
