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authorDamien Le Moal <dlemoal@kernel.org>2023-09-05 09:06:23 +0900
committerDamien Le Moal <dlemoal@kernel.org>2023-09-28 21:23:10 +0900
commit8b4d9469d0b0e553208ee6f62f2807111fde18b9 (patch)
tree5b5cd92a0cea274b8607c4a790e36bfb41ac963b /drivers/ata/libata-core.c
parentff48b37802e5c134e2dfc4d091f10b2eb5065a72 (diff)
ata: libata-scsi: Fix delayed scsi_rescan_device() execution
Commit 6aa0365a3c85 ("ata: libata-scsi: Avoid deadlock on rescan after device resume") modified ata_scsi_dev_rescan() to check the scsi device "is_suspended" power field to ensure that the scsi device associated with an ATA device is fully resumed when scsi_rescan_device() is executed. However, this fix is problematic as: 1) It relies on a PM internal field that should not be used without PM device locking protection. 2) The check for is_suspended and the call to scsi_rescan_device() are not atomic and a suspend PM event may be triggered between them, casuing scsi_rescan_device() to be called on a suspended device and in that function blocking while holding the scsi device lock. This would deadlock a following resume operation. These problems can trigger PM deadlocks on resume, especially with resume operations triggered quickly after or during suspend operations. E.g., a simple bash script like: for (( i=0; i<10; i++ )); do echo "+2 > /sys/class/rtc/rtc0/wakealarm echo mem > /sys/power/state done that triggers a resume 2 seconds after starting suspending a system can quickly lead to a PM deadlock preventing the system from correctly resuming. Fix this by replacing the check on is_suspended with a check on the return value given by scsi_rescan_device() as that function will fail if called against a suspended device. Also make sure rescan tasks already scheduled are first cancelled before suspending an ata port. Fixes: 6aa0365a3c85 ("ata: libata-scsi: Avoid deadlock on rescan after device resume") Cc: stable@vger.kernel.org Signed-off-by: Damien Le Moal <dlemoal@kernel.org> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/ata/libata-core.c')
-rw-r--r--drivers/ata/libata-core.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index a0bc01606b30..092372334e92 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5168,11 +5168,27 @@ static const unsigned int ata_port_suspend_ehi = ATA_EHI_QUIET
static void ata_port_suspend(struct ata_port *ap, pm_message_t mesg)
{
+ /*
+ * We are about to suspend the port, so we do not care about
+ * scsi_rescan_device() calls scheduled by previous resume operations.
+ * The next resume will schedule the rescan again. So cancel any rescan
+ * that is not done yet.
+ */
+ cancel_delayed_work_sync(&ap->scsi_rescan_task);
+
ata_port_request_pm(ap, mesg, 0, ata_port_suspend_ehi, false);
}
static void ata_port_suspend_async(struct ata_port *ap, pm_message_t mesg)
{
+ /*
+ * We are about to suspend the port, so we do not care about
+ * scsi_rescan_device() calls scheduled by previous resume operations.
+ * The next resume will schedule the rescan again. So cancel any rescan
+ * that is not done yet.
+ */
+ cancel_delayed_work_sync(&ap->scsi_rescan_task);
+
ata_port_request_pm(ap, mesg, 0, ata_port_suspend_ehi, true);
}