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Message-Id: <20200929203459.515312515@linutronix.de>
Date: Tue, 29 Sep 2020 22:25:10 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Peter Zijlstra <peterz@...radead.org>,
Paul McKenney <paulmck@...nel.org>,
Matthew Wilcox <willy@...radead.org>,
Christian Benvenuti <benve@...co.com>,
Govindarajulu Varadarajan <_govind@....com>,
Dave Miller <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
Jonathan Corbet <corbet@....net>,
Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
linux-doc@...r.kernel.org,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
Jay Cliburn <jcliburn@...il.com>,
Chris Snook <chris.snook@...il.com>,
Vishal Kulkarni <vishal@...lsio.com>,
Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
intel-wired-lan@...ts.osuosl.org,
Shannon Nelson <snelson@...sando.io>,
Pensando Drivers <drivers@...sando.io>,
Andrew Lunn <andrew@...n.ch>,
Heiner Kallweit <hkallweit1@...il.com>,
Russell King <linux@...linux.org.uk>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Solarflare linux maintainers <linux-net-drivers@...arflare.com>,
Edward Cree <ecree@...arflare.com>,
Martin Habets <mhabets@...arflare.com>,
Jon Mason <jdmason@...zu.us>, Daniel Drake <dsd@...too.org>,
Ulrich Kunitz <kune@...ne-taler.de>,
Kalle Valo <kvalo@...eaurora.org>,
linux-wireless@...r.kernel.org, linux-usb@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Arend van Spriel <arend.vanspriel@...adcom.com>,
Franky Lin <franky.lin@...adcom.com>,
Hante Meuleman <hante.meuleman@...adcom.com>,
Chi-Hsien Lin <chi-hsien.lin@...ress.com>,
Wright Feng <wright.feng@...ress.com>,
brcm80211-dev-list.pdl@...adcom.com,
brcm80211-dev-list@...ress.com,
Stanislav Yakovlev <stas.yakovlev@...il.com>,
Stanislaw Gruszka <stf_xl@...pl>,
Johannes Berg <johannes.berg@...el.com>,
Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
Luca Coelho <luciano.coelho@...el.com>,
Intel Linux Wireless <linuxwifi@...el.com>,
Jouni Malinen <j@...fi>,
Amitkumar Karwar <amitkarwar@...il.com>,
Ganapathi Bhat <ganapathi.bhat@....com>,
Xinming Hu <huxinming820@...il.com>,
libertas-dev@...ts.infradead.org,
Pascal Terjan <pterjan@...gle.com>,
Ping-Ke Shih <pkshih@...ltek.com>
Subject: [patch V2 01/36] net: enic: Cure the enic api locking trainwreck
From: Thomas Gleixner <tglx@...utronix.de>
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>
---
V2: Cure tglx's last minute rename fail
---
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(-)
--- 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 */
--- 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(struc
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);
--- a/drivers/net/ethernet/cisco/enic/enic_main.c
+++ b/drivers/net/ethernet/cisco/enic/enic_main.c
@@ -2107,8 +2107,6 @@ static int enic_dev_wait(struct vnic_dev
int done;
int err;
- BUG_ON(in_interrupt());
-
err = start(vdev, arg);
if (err)
return err;
@@ -2297,6 +2295,13 @@ static int enic_set_rss_nic_cfg(struct e
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);
@@ -2306,7 +2311,9 @@ static void enic_reset(struct work_struc
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);
@@ -2314,7 +2321,10 @@ static void enic_reset(struct work_struc
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();
@@ -2326,7 +2336,9 @@ static void enic_tx_hang_reset(struct wo
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);
@@ -2335,7 +2347,10 @@ static void enic_tx_hang_reset(struct wo
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();
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