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

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

diff --git a/kernel/events/core.c b/kernel/events/core.c
index ca4c1242c29b50bb0249439ec08f765a1eecefd2..773875aaa2916288ff39519cf54160b13802c140 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -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);