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authorMilton Miller <miltonm@us.ibm.com>2021-03-29 10:20:39 -0500
committerDavid S. Miller <davem@davemloft.net>2021-03-30 13:16:23 -0700
commit03cb4d05b4ea9a3491674ca40952adb708d549fa (patch)
tree11878971da567ed502e09de27539da61a45a77d3 /net/ncsi
parent6e5a03bcba44e080a6bf300194a68ce9bb1e5184 (diff)
downloadlinux-03cb4d05b4ea9a3491674ca40952adb708d549fa.tar.bz2
net/ncsi: Avoid channel_monitor hrtimer deadlock
Calling ncsi_stop_channel_monitor from channel_monitor is a guaranteed deadlock on SMP because stop calls del_timer_sync on the timer that invoked channel_monitor as its timer function. Recognise the inherent race of marking the monitor disabled before deleting the timer by just returning if enable was cleared. After a timeout (the default case -- reset to START when response received) just mark the monitor.enabled false. If the channel has an entry on the channel_queue list, or if the state is not ACTIVE or INACTIVE, then warn and mark the timer stopped and don't restart, as the locking is broken somehow. Fixes: 0795fb2021f0 ("net/ncsi: Stop monitor if channel times out or is inactive") Signed-off-by: Milton Miller <miltonm@us.ibm.com> Signed-off-by: Eddie James <eajames@linux.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ncsi')
-rw-r--r--net/ncsi/ncsi-manage.c20
1 files changed, 13 insertions, 7 deletions
diff --git a/net/ncsi/ncsi-manage.c b/net/ncsi/ncsi-manage.c
index a9cb355324d1..ffff8da707b8 100644
--- a/net/ncsi/ncsi-manage.c
+++ b/net/ncsi/ncsi-manage.c
@@ -105,13 +105,20 @@ static void ncsi_channel_monitor(struct timer_list *t)
monitor_state = nc->monitor.state;
spin_unlock_irqrestore(&nc->lock, flags);
- if (!enabled || chained) {
- ncsi_stop_channel_monitor(nc);
- return;
- }
+ if (!enabled)
+ return; /* expected race disabling timer */
+ if (WARN_ON_ONCE(chained))
+ goto bad_state;
+
if (state != NCSI_CHANNEL_INACTIVE &&
state != NCSI_CHANNEL_ACTIVE) {
- ncsi_stop_channel_monitor(nc);
+bad_state:
+ netdev_warn(ndp->ndev.dev,
+ "Bad NCSI monitor state channel %d 0x%x %s queue\n",
+ nc->id, state, chained ? "on" : "off");
+ spin_lock_irqsave(&nc->lock, flags);
+ nc->monitor.enabled = false;
+ spin_unlock_irqrestore(&nc->lock, flags);
return;
}
@@ -136,10 +143,9 @@ static void ncsi_channel_monitor(struct timer_list *t)
ncsi_report_link(ndp, true);
ndp->flags |= NCSI_DEV_RESHUFFLE;
- ncsi_stop_channel_monitor(nc);
-
ncm = &nc->modes[NCSI_MODE_LINK];
spin_lock_irqsave(&nc->lock, flags);
+ nc->monitor.enabled = false;
nc->state = NCSI_CHANNEL_INVISIBLE;
ncm->data[2] &= ~0x1;
spin_unlock_irqrestore(&nc->lock, flags);