Thomas Gleixner df63949a27 net: enic: Cure the enic api locking trainwreck ... [ Upstream commit a53b59ece8 ] 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: 0b038566c0 ("drivers/net: enic: Add an interface for USNIC to interact with firmware") Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>		2020-10-29 09:57:43 +01:00
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Kconfig	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
cq_desc.h	…
cq_enet_desc.h	…
enic.h	net: enic: Cure the enic api locking trainwreck	2020-10-29 09:57:43 +01:00
enic_api.c	net: enic: Cure the enic api locking trainwreck	2020-10-29 09:57:43 +01:00
enic_api.h	…
enic_clsf.c	drivers: net: Remove unnecessary semicolon	2019-03-01 23:13:49 -08:00
enic_clsf.h	treewide: setup_timer() -> timer_setup() (2 field)	2017-11-21 15:57:09 -08:00
enic_dev.c	…
enic_dev.h	…
enic_ethtool.c	net: core: dev: Add extack argument to dev_open()	2018-12-06 13:26:06 -08:00
enic_main.c	net: enic: Cure the enic api locking trainwreck	2020-10-29 09:57:43 +01:00
enic_pp.c	…
enic_pp.h	…
enic_res.c	enic: fix UDP rss bits	2018-06-06 09:09:09 -04:00
enic_res.h	…
rq_enet_desc.h	…
vnic_cq.c	…
vnic_cq.h	…
vnic_dev.c	net: cisco: enic: Replace GFP_ATOMIC with GFP_KERNEL	2018-08-04 13:08:06 -07:00
vnic_dev.h	enic: fix UDP rss bits	2018-06-06 09:09:09 -04:00
vnic_devcmd.h	enic: fix UDP rss bits	2018-06-06 09:09:09 -04:00
vnic_enet.h	…
vnic_intr.c	…
vnic_intr.h	…
vnic_nic.h	enic: fix UDP rss bits	2018-06-06 09:09:09 -04:00
vnic_resource.h	…
vnic_rq.c	net: cisco: enic: Replace GFP_ATOMIC with GFP_KERNEL	2018-08-04 13:08:06 -07:00
vnic_rq.h	…
vnic_rss.h	…
vnic_stats.h	…
vnic_vic.c	…
vnic_vic.h	…
vnic_wq.c	net: cisco: enic: Replace GFP_ATOMIC with GFP_KERNEL	2018-08-04 13:08:06 -07:00
vnic_wq.h	…
wq_enet_desc.h	…