diff options
author | Johannes Berg <johannes.berg@intel.com> | 2023-11-24 19:25:26 +0300 |
---|---|---|
committer | Johannes Berg <johannes.berg@intel.com> | 2023-11-27 13:24:55 +0300 |
commit | 8c88a474357ead632b07c70bf7f119ace8c3b39e (patch) | |
tree | 31c18cdb506b19cef567f05306f958c3d65c9dfa /fs/debugfs/inode.c | |
parent | f4acfcd4deb158b96595250cc332901b282d15b0 (diff) | |
download | linux-8c88a474357ead632b07c70bf7f119ace8c3b39e.tar.xz |
debugfs: add API to allow debugfs operations cancellation
In some cases there might be longer-running hardware accesses
in debugfs files, or attempts to acquire locks, and we want
to still be able to quickly remove the files.
Introduce a cancellations API to use inside the debugfs handler
functions to be able to cancel such operations on a per-file
basis.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'fs/debugfs/inode.c')
-rw-r--r-- | fs/debugfs/inode.c | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index 80f4f000dcc1..d53c2860b03c 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -247,6 +247,8 @@ static void debugfs_release_dentry(struct dentry *dentry) lockdep_unregister_key(&fsd->key); kfree(fsd->lock_name); #endif + WARN_ON(!list_empty(&fsd->cancellations)); + mutex_destroy(&fsd->cancellations_mtx); } kfree(fsd); @@ -756,8 +758,36 @@ static void __debugfs_file_removed(struct dentry *dentry) lock_map_acquire(&fsd->lockdep_map); lock_map_release(&fsd->lockdep_map); - if (!refcount_dec_and_test(&fsd->active_users)) + /* 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; + } + + /* if we didn't hit zero, try to cancel any we can */ + while (refcount_read(&fsd->active_users)) { + struct debugfs_cancellation *c; + + /* + * Lock the cancellations. Note that the cancellations + * structs are meant to be on the stack, so we need to + * ensure we either use them here or don't touch them, + * and debugfs_leave_cancellation() will wait for this + * to be finished processing before exiting one. It may + * of course win and remove the cancellation, but then + * chances are we never even got into this bit, we only + * do if the refcount isn't zero already. + */ + mutex_lock(&fsd->cancellations_mtx); + while ((c = list_first_entry_or_null(&fsd->cancellations, + typeof(*c), list))) { + list_del_init(&c->list); + c->cancel(dentry, c->cancel_data); + } + mutex_unlock(&fsd->cancellations_mtx); + + wait_for_completion(&fsd->active_users_drained); + } } static void remove_one(struct dentry *victim) |