Commit 7e71c55e authored by Steven Whitehouse's avatar Steven Whitehouse
Browse files

GFS2: Fix potential race in glock code 



We need to be careful of the ordering between clearing the
GLF_LOCK bit and scheduling the workqueue.

Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent 22763c5c

fs/gfs2/glock.c

+8 −2
Original line number Diff line number Diff line
@@ -672,12 +672,17 @@ __acquires(&gl->gl_spin) 
	return;



out_sched:

	clear_bit(GLF_LOCK, &gl->gl_flags);

	smp_mb__after_clear_bit();

	gfs2_glock_hold(gl);

	if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)

		gfs2_glock_put_nolock(gl);

	return;



out_unlock:

	clear_bit(GLF_LOCK, &gl->gl_flags);

	goto out;

	smp_mb__after_clear_bit();

	return;

}



static void delete_work_func(struct work_struct *work)
@@ -1375,10 +1380,11 @@ static int gfs2_shrink_glock_memory(int nr, gfp_t gfp_mask) 
				handle_callback(gl, LM_ST_UNLOCKED, 0);

				nr--;

			}

			clear_bit(GLF_LOCK, &gl->gl_flags);

			smp_mb__after_clear_bit();

			if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)

				gfs2_glock_put_nolock(gl);

			spin_unlock(&gl->gl_spin);

			clear_bit(GLF_LOCK, &gl->gl_flags);

			spin_lock(&lru_lock);

			continue;

		}