Commit 0983593f authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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perf/core: Lift event->mmap_mutex in perf_mmap() 



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

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarRavi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/r/20241104135519.582252957@infradead.org
parent 8eaec7bb

kernel/events/core.c

+8 −12
Original line number Diff line number Diff line
@@ -6680,7 +6680,7 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) 
	unsigned long vma_size;

	unsigned long nr_pages;

	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
@@ -6708,6 +6708,9 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) 


	user_extra = nr_pages;



	mutex_lock(&event->mmap_mutex);

	ret = -EINVAL;



	if (vma->vm_pgoff == 0) {

		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.

		 */

		if (nr_pages != 0 && !is_power_of_2(nr_pages))

			return -EINVAL;

			goto unlock;



		WARN_ON_ONCE(event->ctx->parent_ctx);

		mutex_lock(&event->mmap_mutex);



		if (event->rb) {

			if (data_page_nr(event->rb) != nr_pages) {

				ret = -EINVAL;

			if (data_page_nr(event->rb) != nr_pages)

				goto unlock;

			}



			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;



		if (!event->rb)

			return -EINVAL;



		mutex_lock(&event->mmap_mutex);

		ret = -EINVAL;



		rb = event->rb;

		if (!rb)

			goto aux_unlock;
@@ -6869,6 +6863,8 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) 
			rb->aux_mmap_locked = extra;

	}



	ret = 0;



unlock:

	if (!ret) {

		atomic_long_add(user_extra, &user->locked_vm);