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authorRoland Dreier <rolandd@cisco.com>2009-09-07 08:27:50 -0700
committerRoland Dreier <rolandd@cisco.com>2009-09-07 08:27:50 -0700
commit6b2eef8fd78ff909c3396b8671d57c42559cc51d (patch)
tree98557140c16bc825a82bfd414fedda46749dbbf7 /drivers/infiniband
parent60f2b652f54aa4ac4127a538abad05235fb9c469 (diff)
IB/mad: Fix possible lock-lock-timer deadlock
Lockdep reported a possible deadlock with cm_id_priv->lock, mad_agent_priv->lock and mad_agent_priv->timed_work.timer; this happens because the mad module does cancel_delayed_work(&mad_agent_priv->timed_work); while holding mad_agent_priv->lock. cancel_delayed_work() internally does del_timer_sync(&mad_agent_priv->timed_work.timer). This can turn into a deadlock because mad_agent_priv->lock is taken inside cm_id_priv->lock, so we can get the following set of contexts that deadlock each other: A: holding cm_id_priv->lock, waiting for mad_agent_priv->lock B: holding mad_agent_priv->lock, waiting for del_timer_sync() C: interrupt during mad_agent_priv->timed_work.timer that takes cm_id_priv->lock Fix this by using the new __cancel_delayed_work() interface (which internally does del_timer() instead of del_timer_sync()) in all the places where we are holding a lock. Addresses: http://bugzilla.kernel.org/show_bug.cgi?id=13757 Reported-by: Bart Van Assche <bart.vanassche@gmail.com> Signed-off-by: Roland Dreier <rolandd@cisco.com>
Diffstat (limited to 'drivers/infiniband')
-rw-r--r--drivers/infiniband/core/mad.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
index de922a04ca2..bc30c00c5d7 100644
--- a/drivers/infiniband/core/mad.c
+++ b/drivers/infiniband/core/mad.c
@@ -1974,7 +1974,7 @@ static void adjust_timeout(struct ib_mad_agent_private *mad_agent_priv)
unsigned long delay;
if (list_empty(&mad_agent_priv->wait_list)) {
- cancel_delayed_work(&mad_agent_priv->timed_work);
+ __cancel_delayed_work(&mad_agent_priv->timed_work);
} else {
mad_send_wr = list_entry(mad_agent_priv->wait_list.next,
struct ib_mad_send_wr_private,
@@ -1983,7 +1983,7 @@ static void adjust_timeout(struct ib_mad_agent_private *mad_agent_priv)
if (time_after(mad_agent_priv->timeout,
mad_send_wr->timeout)) {
mad_agent_priv->timeout = mad_send_wr->timeout;
- cancel_delayed_work(&mad_agent_priv->timed_work);
+ __cancel_delayed_work(&mad_agent_priv->timed_work);
delay = mad_send_wr->timeout - jiffies;
if ((long)delay <= 0)
delay = 1;
@@ -2023,7 +2023,7 @@ static void wait_for_response(struct ib_mad_send_wr_private *mad_send_wr)
/* Reschedule a work item if we have a shorter timeout */
if (mad_agent_priv->wait_list.next == &mad_send_wr->agent_list) {
- cancel_delayed_work(&mad_agent_priv->timed_work);
+ __cancel_delayed_work(&mad_agent_priv->timed_work);
queue_delayed_work(mad_agent_priv->qp_info->port_priv->wq,
&mad_agent_priv->timed_work, delay);
}