Messages in this thread Patch in this message | | | Date | Thu, 17 Apr 2008 11:41:23 -0400 (EDT) | From | Steven Rostedt <> | Subject | [PATCH] lockdep: comment hidden releases of graph_lock |
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While reviewing the lockdep.c code, it looked to me that I found a bug where the release of the graph_lock was not done on failure. This turns out not to be the case, because the graph_unlock is performed within the internal functions of lockdep when a failure occurs.
To help out others when visually reviewing this code, I've added comments to the places where it looks like it may be a bug not to call graph_unlock.
Signed-off-by: Steven Rostedt <srostedt@redhat.com> --- kernel/lockdep.c | 3 +++ 1 file changed, 3 insertions(+)
Index: linux-sched-devel.git/kernel/lockdep.c =================================================================== --- linux-sched-devel.git.orig/kernel/lockdep.c 2008-04-17 10:52:40.000000000 -0400 +++ linux-sched-devel.git/kernel/lockdep.c 2008-04-17 11:20:49.000000000 -0400 @@ -1566,6 +1566,7 @@ static int validate_chain(struct task_st /* * Add dependency only if this lock is not the head * of the chain, and if it's not a secondary read-lock: + * (will do graph_unlock on failure) */ if (!chain_head && ret != 2) if (!check_prevs_add(curr, hlock)) @@ -2284,6 +2285,7 @@ static int mark_lock(struct task_struct
this->class->usage_mask |= new_mask;
+ /* save_trace does graph_unlock on failure */ if (!save_trace(this->class->usage_traces + new_bit)) return 0;
@@ -2296,6 +2298,7 @@ static int mark_lock(struct task_struct case LOCK_ENABLED_SOFTIRQS: case LOCK_ENABLED_HARDIRQS_READ: case LOCK_ENABLED_SOFTIRQS_READ: + /* mark_lock_irq does graph_unlock on failure */ ret = mark_lock_irq(curr, this, new_bit); if (!ret) return 0;
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