ata: libata-scsi: Avoid deadlock on rescan after device resume
When an ATA port is resumed from sleep, the port is reset and a power management request issued to libata EH to reset the port and rescanning the device(s) attached to the port. Device rescanning is done by scheduling an ata_scsi_dev_rescan() work, which will execute scsi_rescan_device(). However, scsi_rescan_device() takes the generic device lock, which is also taken by dpm_resume() when the SCSI device is resumed as well. If a device rescan execution starts before the completion of the SCSI device resume, the rcu locking used to refresh the cached VPD pages of the device, combined with the generic device locking from scsi_rescan_device() and from dpm_resume() can cause a deadlock. Avoid this situation by changing struct ata_port scsi_rescan_task to be a delayed work instead of a simple work_struct. ata_scsi_dev_rescan() is modified to check if the SCSI device associated with the ATA device that must be rescanned is not suspended. If the SCSI device is still suspended, ata_scsi_dev_rescan() returns early and reschedule itself for execution after an arbitrary delay of 5ms. Reported-by:Kai-Heng Feng <kai.heng.feng@canonical.com> Reported-by:
Joe Breuer <linux-kernel@jmbreuer.net> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217530 Fixes: a19a93e4 ("scsi: core: pm: Rely on the device driver core for async power management") Signed-off-by:
Damien Le Moal <dlemoal@kernel.org> Reviewed-by:
Hannes Reinecke <hare@suse.de> Tested-by:
Kai-Heng Feng <kai.heng.feng@canonical.com> Tested-by:
Joe Breuer <linux-kernel@jmbreuer.net>
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