The following commit has been merged into the perf/core branch of tip: Commit-ID: 7503c90c0df8d0178be66d53705eacd9e843d762 Gitweb: https://git.kernel.org/tip/7503c90c0df8d0178be66d53705eacd9e843d762 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Mon, 04 Nov 2024 14:39:23 +01:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Sat, 01 Mar 2025 20:12:53 +01:00 perf/core: Simplify the perf_mmap() control flow Identity-transform: if (c) { X1; } else { Y; goto l; } X2; l: into the simpler: if (c) { X1; X2; } else { Y; } [ mingo: Forward ported it ] Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Link: https://lore.kernel.org/r/20241104135519.095904637@xxxxxxxxxxxxx --- kernel/events/core.c | 75 ++++++++++++++++++++----------------------- 1 file changed, 36 insertions(+), 39 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index ab4e497..d1b04c8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6701,6 +6701,42 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) if (vma->vm_pgoff == 0) { nr_pages = (vma_size / PAGE_SIZE) - 1; + + /* + * If we have rb pages ensure they're a power-of-two number, so we + * can do bitmasks instead of modulo. + */ + if (nr_pages != 0 && !is_power_of_2(nr_pages)) + return -EINVAL; + + if (vma_size != PAGE_SIZE * (1 + nr_pages)) + return -EINVAL; + + WARN_ON_ONCE(event->ctx->parent_ctx); +again: + mutex_lock(&event->mmap_mutex); + if (event->rb) { + if (data_page_nr(event->rb) != nr_pages) { + ret = -EINVAL; + goto unlock; + } + + if (!atomic_inc_not_zero(&event->rb->mmap_count)) { + /* + * Raced against perf_mmap_close(); remove the + * event and try again. + */ + ring_buffer_attach(event, NULL); + mutex_unlock(&event->mmap_mutex); + goto again; + } + + /* We need the rb to map pages. */ + rb = event->rb; + goto unlock; + } + + user_extra = nr_pages + 1; } else { /* * AUX area mapping: if rb->aux_nr_pages != 0, it's already @@ -6760,47 +6796,8 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) atomic_set(&rb->aux_mmap_count, 1); user_extra = nr_pages; - - goto accounting; - } - - /* - * If we have rb pages ensure they're a power-of-two number, so we - * can do bitmasks instead of modulo. - */ - if (nr_pages != 0 && !is_power_of_2(nr_pages)) - return -EINVAL; - - if (vma_size != PAGE_SIZE * (1 + nr_pages)) - return -EINVAL; - - WARN_ON_ONCE(event->ctx->parent_ctx); -again: - mutex_lock(&event->mmap_mutex); - if (event->rb) { - if (data_page_nr(event->rb) != nr_pages) { - ret = -EINVAL; - goto unlock; - } - - if (!atomic_inc_not_zero(&event->rb->mmap_count)) { - /* - * Raced against perf_mmap_close(); remove the - * event and try again. - */ - ring_buffer_attach(event, NULL); - mutex_unlock(&event->mmap_mutex); - goto again; - } - - /* We need the rb to map pages. */ - rb = event->rb; - goto unlock; } - user_extra = nr_pages + 1; - -accounting: user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10); /*
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