On 2/27/24 06:32, Johannes Berg wrote:
On Tue, 2024-02-27 at 06:29 -0800, Ben Greear wrote:
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -751,13 +751,19 @@ static void __debugfs_file_removed(struct dentry *dentry)
if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
return;
- /* if we hit zero, just wait for all to finish */
- if (!refcount_dec_and_test(&fsd->active_users)) {
- wait_for_completion(&fsd->active_users_drained);
- return;
- }
+ /*
+ * Now that debugfs_file_get() no longer sees a valid entry,
+ * decrement the refcount to remove the initial reference.
+ */
+ refcount_dec(&fsd->active_users);
[ 94.576688] ------------[ cut here ]------------
[ 94.576699] refcount_t: decrement hit 0; leaking memory.
Ah ... right, refcount_dec() doesn't like to hit 0, it's not meant for
this path.
I guess we can
if (refcount_dec_and_test(...))
return;
while (refcount_read(...)) { ... }
johannes
Like this?
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 034a617cb1a5..166053095610 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -751,13 +751,20 @@ static void __debugfs_file_removed(struct dentry *dentry)
if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT)
return;
- /* if we hit zero, just wait for all to finish */
- if (!refcount_dec_and_test(&fsd->active_users)) {
- wait_for_completion(&fsd->active_users_drained);
+ /*
+ * Now that debugfs_file_get() no longer sees a valid entry,
+ * decrement the refcount to remove the initial reference.
+ */
+ if (!refcount_dec_and_test(&fsd->active_users))
return;
- }
- /* if we didn't hit zero, try to cancel any we can */
+ /*
+ * As long as it's not zero, try to cancel any cancellations,
+ * new incoming ones will wake up the completion as we might
+ * have raced: debugfs_file_get() had already been done, but
+ * debugfs_enter_cancellation() hadn't, by the time we got
+ * to this point here.
+ */
while (refcount_read(&fsd->active_users)) {
struct debugfs_cancellation *c;
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
