scsi: smartpqi: Fix logical volume rescan race condition

scsi: smartpqi: Fix logical volume rescan race condition

[ Upstream commit fb4cece17b4583f55b34a8538e27a4adc833c9d4 ]

Correct rescan flag race condition.

Multiple conditions are being evaluated before notifying OS to do a rescan.

Driver will skip rescanning the device if any one of the following
conditions are met:

 - Devices that have not yet been added to the OS or devices that have been
   removed.

 - Devices which are already marked for removal or in the phase of removal.

Under very rare conditions, after logical volume size expansion, the OS
still sees the size of the logical volume which was before expansion.

The rescan flag in the driver is used to signal the need for a logical
volume rescan. A race condition can occur in the driver, and it leads to
one thread overwriting the flag inadvertently. As a result, driver is not
notifying the OS SML to rescan the logical volume.

Move device->rescan update into new function pqi_mark_volumes_for_rescan()
and protect with a spin lock.

Move check for device->rescan into new function pqi_volume_rescan_needed()
and protect function call with a spin_lock.

Reviewed-by: Scott Teel <scott.teel@microchip.com>
Reviewed-by: Scott Benesh <scott.benesh@microchip.com>
Reviewed-by: Mike McGowen <mike.mcgowen@microchip.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microchip.com>
Co-developed-by: Murthy Bhat <Murthy.Bhat@microchip.com>
Signed-off-by: Murthy Bhat <Murthy.Bhat@microchip.com>
Signed-off-by: Mahesh Rajashekhara <mahesh.rajashekhara@microchip.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
Link: https://lore.kernel.org/r/20231219193653.277553-3-don.brace@microchip.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>