We skip lockdep annotations for sysfs attributes with ignore_lockdep set. An exception is kernfs_deactivate where we annotate even in this case. Since the lockdep map key needed for the annotation is not initialized whenever ignore_lockdep is set, we'll get a warning for the uninitialized key.
Note that this happens since, commit 517e64f57883bd63c5a4ab8b3d0d3ed68c55d0cf Author: Tejun Heo <t...@kernel.org> Date: Thu Nov 28 14:54:29 2013 -0500 Before this change we had a valid key even in case of ignore_lockdep, so the annotation in kernfs_deactivate worked, or at least didn't produce the above warning. Fix this by skipping the annotation whenever ignore_lockdep is set. The actual attribute triggering the bug was 'delete_device' in drivers/i2c/i2c-core.c, for the backtrace see the reference below. Reported-by: Borislav Petkov <b...@alien8.de> Reference: http://lists.freedesktop.org/archives/intel-gfx/2014-February/039663.html Signed-off-by: Imre Deak <imre.d...@intel.com> --- fs/kernfs/dir.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 5104cf5..bd6e18b 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -187,19 +187,23 @@ static void kernfs_deactivate(struct kernfs_node *kn) kn->u.completion = (void *)&wait; - rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); + if (kn->flags & KERNFS_LOCKDEP) + rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); /* atomic_add_return() is a mb(), put_active() will always see * the updated kn->u.completion. */ v = atomic_add_return(KN_DEACTIVATED_BIAS, &kn->active); if (v != KN_DEACTIVATED_BIAS) { - lock_contended(&kn->dep_map, _RET_IP_); + if (kn->flags & KERNFS_LOCKDEP) + lock_contended(&kn->dep_map, _RET_IP_); wait_for_completion(&wait); } - lock_acquired(&kn->dep_map, _RET_IP_); - rwsem_release(&kn->dep_map, 1, _RET_IP_); + if (kn->flags & KERNFS_LOCKDEP) { + lock_acquired(&kn->dep_map, _RET_IP_); + rwsem_release(&kn->dep_map, 1, _RET_IP_); + } } /** -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
