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Sumit Saxena 8e781506a7 scsi: megaraid_sas: Fix concurrent access to ISR between IRQ polling and real interrupt

[ Upstream commit e7dcc514a49e74051b869697d5ab0370f6301d57 ]

IRQ polling thread calls ISR after enable_irq() to handle any missed I/O
completion. The atomic flag "in_used" was added to have the synchronization
between the IRQ polling thread and the interrupt context. There is a bug
around it leading to a race condition.

Below is the sequence:

 - IRQ polling thread accesses ISR, fetches the reply descriptor.

 - Real interrupt arrives and pre-empts polling thread (enable_irq() is
   already called).

 - Interrupt context picks the same reply descriptor as fetched by polling
   thread, processes it, and exits.

 - Polling thread resumes and processes the descriptor which is already
   processed by interrupt thread leads to kernel crash.

Setting the "in_used" flag before fetching the reply descriptor ensures
synchronized access to ISR.

Link: https://www.spinics.net/lists/linux-scsi/msg159440.html
Link: https://lore.kernel.org/r/20210929124022.24605-2-sumit.saxena@broadcom.com
Fixes: 9bedd36e9146 ("scsi: megaraid_sas: Handle missing interrupts while re-enabling IRQs")
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

2021-11-18 19:16:50 +01:00

Kconfig.megaraid

SCSI misc on 20190709

2019-07-11 15:14:01 -07:00

Makefile

scsi: megaraid_sas: Export RAID map through debugfs

2019-06-18 19:46:20 -04:00

mbox_defs.h

treewide: remove editor modelines and cruft

2021-05-07 00:26:34 -07:00

mega_common.h

treewide: remove editor modelines and cruft