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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-05-03 21:38:55 +0300
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-06-09 04:52:31 +0300
commitfa3c66476975abf00c97f27b6c2b3d223f7d57f5 (patch)
tree3f39de6eb3438f8910e5a40fda19e79fd4813689 /kernel/rcu
parent752de307b0ee47308bfc299de3a3ad623c16b4d8 (diff)
downloadlinux-fa3c66476975abf00c97f27b6c2b3d223f7d57f5.tar.xz
rcu: Improve __call_rcu() debug-objects error message
The "__call_rcu(): Leaked duplicate callback" error message from __call_rcu() has proven to be unhelpful. This commit therefore changes it to "__call_rcu(): Double-freed CB" and adds the value of the pointer passed in. The value of the pointer improves debuggability by allowing correlation with tracing output, for example, the rcu:rcu_callback trace event. Reported-by: Vegard Nossum <vegard.nossum@oracle.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 61a97164abcc..cac24f5d3fd2 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3161,9 +3161,14 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func,
WARN_ON_ONCE((unsigned long)head & (sizeof(void *) - 1));
if (debug_rcu_head_queue(head)) {
- /* Probable double call_rcu(), so leak the callback. */
+ /*
+ * Probable double call_rcu(), so leak the callback.
+ * Use rcu:rcu_callback trace event to find the previous
+ * time callback was passed to __call_rcu().
+ */
+ WARN_ONCE(1, "__call_rcu(): Double-freed CB %p->%pF()!!!\n",
+ head, head->func);
WRITE_ONCE(head->func, rcu_leak_callback);
- WARN_ONCE(1, "__call_rcu(): Leaked duplicate callback\n");
return;
}
head->func = func;