diff options
author | Milton Miller <miltonm@us.ibm.com> | 2021-03-29 18:20:39 +0300 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2021-03-30 23:16:23 +0300 |
commit | 03cb4d05b4ea9a3491674ca40952adb708d549fa (patch) | |
tree | 11878971da567ed502e09de27539da61a45a77d3 /net | |
parent | 6e5a03bcba44e080a6bf300194a68ce9bb1e5184 (diff) | |
download | linux-03cb4d05b4ea9a3491674ca40952adb708d549fa.tar.xz |
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')
-rw-r--r-- | net/ncsi/ncsi-manage.c | 20 |
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); |