diff options
author | Milton Miller <miltonm@us.ibm.com> | 2021-03-29 10:20:39 -0500 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-04-16 11:57:50 +0200 |
commit | 1c1791e0ebee2281784e5fb108cf6d56891be734 (patch) | |
tree | 72e4dcf20643d7bc08ce1c74b12e8a9d4055e31b /net | |
parent | bb271612b3c79612ed7592bb25ce1431c6f88c6c (diff) |
net/ncsi: Avoid channel_monitor hrtimer deadlock
[ Upstream commit 03cb4d05b4ea9a3491674ca40952adb708d549fa ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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 28c42b22b748..6b7f9e1f64d3 100644 --- a/net/ncsi/ncsi-manage.c +++ b/net/ncsi/ncsi-manage.c @@ -203,13 +203,20 @@ static void ncsi_channel_monitor(unsigned long data) 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; } @@ -234,10 +241,9 @@ static void ncsi_channel_monitor(unsigned long data) 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); |