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perf/core: Lift event->mmap_mutex in perf_mmap()

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This puts 'all' of perf_mmap() under single event->mmap_mutex.

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/20241104135519.582252957@infradead.org
This commit is contained in:
Peter Zijlstra 2024-11-04 14:39:27 +01:00 • committed by Ingo Molnar
parent 8eaec7bb72
commit 0983593f32
1 changed files with 8 additions and 12 deletions
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20
kernel/events/core.c
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@ -6680,7 +6680,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
unsigned long vma_size; unsigned long vma_size;
unsigned long nr_pages; unsigned long nr_pages;
long user_extra = 0, extra = 0; long user_extra = 0, extra = 0;
int ret = 0, flags = 0; int ret, flags = 0;
/* /*
* Don't allow mmap() of inherited per-task counters. This would * Don't allow mmap() of inherited per-task counters. This would
@ -6708,6 +6708,9 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
user_extra = nr_pages; user_extra = nr_pages;
mutex_lock(&event->mmap_mutex);
ret = -EINVAL;
if (vma->vm_pgoff == 0) { if (vma->vm_pgoff == 0) {
nr_pages -= 1; nr_pages -= 1;
@ -6716,16 +6719,13 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
* can do bitmasks instead of modulo. * can do bitmasks instead of modulo.
*/ */
if (nr_pages != 0 && !is_power_of_2(nr_pages)) if (nr_pages != 0 && !is_power_of_2(nr_pages))
return -EINVAL; goto unlock;
WARN_ON_ONCE(event->ctx->parent_ctx); WARN_ON_ONCE(event->ctx->parent_ctx);
mutex_lock(&event->mmap_mutex);
if (event->rb) { if (event->rb) {
if (data_page_nr(event->rb) != nr_pages) { if (data_page_nr(event->rb) != nr_pages)
ret = -EINVAL;
goto unlock; goto unlock;
}
if (atomic_inc_not_zero(&event->rb->mmap_count)) { if (atomic_inc_not_zero(&event->rb->mmap_count)) {
/* /*
@ -6754,12 +6754,6 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
*/ */
u64 aux_offset, aux_size; u64 aux_offset, aux_size;
if (!event->rb)
return -EINVAL;
mutex_lock(&event->mmap_mutex);
ret = -EINVAL;
rb = event->rb; rb = event->rb;
if (!rb) if (!rb)
goto aux_unlock; goto aux_unlock;
@ -6869,6 +6863,8 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
rb->aux_mmap_locked = extra; rb->aux_mmap_locked = extra;
} }
ret = 0;
unlock: unlock:
if (!ret) { if (!ret) {
atomic_long_add(user_extra, &user->locked_vm); atomic_long_add(user_extra, &user->locked_vm);