The following commit has been merged into the perf/core branch of tip:
Commit-ID: 954878377bc81459b95937a05f01e8ebf6a05083
Gitweb: https://git.kernel.org/tip/954878377bc81459b95937a05f01e8ebf6a05083
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Mon, 04 Nov 2024 14:39:23 +01:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Tue, 04 Mar 2025 09:43:05 +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>
Reviewed-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
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);
/*
|