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perf/core: Simplify the perf_mmap() control flow

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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@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/r/20241104135519.095904637@infradead.org
This commit is contained in:
Peter Zijlstra 2024-11-04 14:39:23 +01:00 committed by Ingo Molnar
parent c5b9678957
commit 954878377b
1 changed files with 36 additions and 39 deletions
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75
kernel/events/core.c
View File

@ -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);
/*