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Date: Tue, 27 Oct 2020 14:49:59 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
"David S. Miller" <davem@...emloft.net>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 349/757] net: enic: Cure the enic api locking trainwreck
From: Thomas Gleixner <tglx@...utronix.de>
[ Upstream commit a53b59ece86c86d16d12ccdaa1ad0c78250a9d96 ]
enic_dev_wait() has a BUG_ON(in_interrupt()).
Chasing the callers of enic_dev_wait() revealed the gems of enic_reset()
and enic_tx_hang_reset() which are both invoked through work queues in
order to be able to call rtnl_lock(). So far so good.
After locking rtnl both functions acquire enic::enic_api_lock which
serializes against the (ab)use from infiniband. This is where the
trainwreck starts.
enic::enic_api_lock is a spin_lock() which implicitly disables preemption,
but both functions invoke a ton of functions under that lock which can
sleep. The BUG_ON(in_interrupt()) does not trigger in that case because it
can't detect the preempt disabled condition.
This clearly has never been tested with any of the mandatory debug options
for 7+ years, which would have caught that for sure.
Cure it by adding a enic_api_busy member to struct enic, which is modified
and evaluated with enic::enic_api_lock held.
If enic_api_devcmd_proxy_by_index() observes enic::enic_api_busy as true,
it drops enic::enic_api_lock and busy waits for enic::enic_api_busy to
become false.
It would be smarter to wait for a completion of that busy period, but
enic_api_devcmd_proxy_by_index() is called with other spin locks held which
obviously can't sleep.
Remove the BUG_ON(in_interrupt()) check as well because it's incomplete and
with proper debugging enabled the problem would have been caught from the
debug checks in schedule_timeout().
Fixes: 0b038566c0ea ("drivers/net: enic: Add an interface for USNIC to interact with firmware")
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
drivers/net/ethernet/cisco/enic/enic.h | 1 +
drivers/net/ethernet/cisco/enic/enic_api.c | 6 +++++
drivers/net/ethernet/cisco/enic/enic_main.c | 27 ++++++++++++++++-----
3 files changed, 28 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/cisco/enic/enic.h b/drivers/net/ethernet/cisco/enic/enic.h
index 18f3aeb88f22a..c67a16a48d624 100644
--- a/drivers/net/ethernet/cisco/enic/enic.h
+++ b/drivers/net/ethernet/cisco/enic/enic.h
@@ -169,6 +169,7 @@ struct enic {
u16 num_vfs;
#endif
spinlock_t enic_api_lock;
+ bool enic_api_busy;
struct enic_port_profile *pp;
/* work queue cache line section */
diff --git a/drivers/net/ethernet/cisco/enic/enic_api.c b/drivers/net/ethernet/cisco/enic/enic_api.c
index b161f24522b87..b028ea2dec2b9 100644
--- a/drivers/net/ethernet/cisco/enic/enic_api.c
+++ b/drivers/net/ethernet/cisco/enic/enic_api.c
@@ -34,6 +34,12 @@ int enic_api_devcmd_proxy_by_index(struct net_device *netdev, int vf,
struct vnic_dev *vdev = enic->vdev;
spin_lock(&enic->enic_api_lock);
+ while (enic->enic_api_busy) {
+ spin_unlock(&enic->enic_api_lock);
+ cpu_relax();
+ spin_lock(&enic->enic_api_lock);
+ }
+
spin_lock_bh(&enic->devcmd_lock);
vnic_dev_cmd_proxy_by_index_start(vdev, vf);
diff --git a/drivers/net/ethernet/cisco/enic/enic_main.c b/drivers/net/ethernet/cisco/enic/enic_main.c
index 552d89fdf54a5..988c0a72e6836 100644
--- a/drivers/net/ethernet/cisco/enic/enic_main.c
+++ b/drivers/net/ethernet/cisco/enic/enic_main.c
@@ -2106,8 +2106,6 @@ static int enic_dev_wait(struct vnic_dev *vdev,
int done;
int err;
- BUG_ON(in_interrupt());
-
err = start(vdev, arg);
if (err)
return err;
@@ -2295,6 +2293,13 @@ static int enic_set_rss_nic_cfg(struct enic *enic)
rss_hash_bits, rss_base_cpu, rss_enable);
}
+static void enic_set_api_busy(struct enic *enic, bool busy)
+{
+ spin_lock(&enic->enic_api_lock);
+ enic->enic_api_busy = busy;
+ spin_unlock(&enic->enic_api_lock);
+}
+
static void enic_reset(struct work_struct *work)
{
struct enic *enic = container_of(work, struct enic, reset);
@@ -2304,7 +2309,9 @@ static void enic_reset(struct work_struct *work)
rtnl_lock();
- spin_lock(&enic->enic_api_lock);
+ /* Stop any activity from infiniband */
+ enic_set_api_busy(enic, true);
+
enic_stop(enic->netdev);
enic_dev_soft_reset(enic);
enic_reset_addr_lists(enic);
@@ -2312,7 +2319,10 @@ static void enic_reset(struct work_struct *work)
enic_set_rss_nic_cfg(enic);
enic_dev_set_ig_vlan_rewrite_mode(enic);
enic_open(enic->netdev);
- spin_unlock(&enic->enic_api_lock);
+
+ /* Allow infiniband to fiddle with the device again */
+ enic_set_api_busy(enic, false);
+
call_netdevice_notifiers(NETDEV_REBOOT, enic->netdev);
rtnl_unlock();
@@ -2324,7 +2334,9 @@ static void enic_tx_hang_reset(struct work_struct *work)
rtnl_lock();
- spin_lock(&enic->enic_api_lock);
+ /* Stop any activity from infiniband */
+ enic_set_api_busy(enic, true);
+
enic_dev_hang_notify(enic);
enic_stop(enic->netdev);
enic_dev_hang_reset(enic);
@@ -2333,7 +2345,10 @@ static void enic_tx_hang_reset(struct work_struct *work)
enic_set_rss_nic_cfg(enic);
enic_dev_set_ig_vlan_rewrite_mode(enic);
enic_open(enic->netdev);
- spin_unlock(&enic->enic_api_lock);
+
+ /* Allow infiniband to fiddle with the device again */
+ enic_set_api_busy(enic, false);
+
call_netdevice_notifiers(NETDEV_REBOOT, enic->netdev);
rtnl_unlock();
--
2.25.1
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