[PATCH v2 2/2] ata: libata-core: fix cancellation of a port deferred qc work

[Damien Le Moal <dlemoal@kernel.org>]

cancel_work_sync() is a sleeping function so it cannot be called with
the spin lock of a port being held. Move the call to this function in
ata_port_detach() after EH completes, with the port lock released,
together with other work cancellation calls.

Fixes: 0ea84089dbf6 ("ata: libata-scsi: avoid Non-NCQ command starvation")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
---
 drivers/ata/libata-core.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index beb6984b379a..d470b7bc92c7 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6269,10 +6269,6 @@ static void ata_port_detach(struct ata_port *ap)
 		}
 	}
 
-	/* Make sure the deferred qc work finished. */
-	cancel_work_sync(&ap->deferred_qc_work);
-	WARN_ON(ap->deferred_qc);
-
 	/* Tell EH to disable all devices */
 	ap->pflags |= ATA_PFLAG_UNLOADING;
 	ata_port_schedule_eh(ap);
@@ -6283,9 +6279,11 @@ static void ata_port_detach(struct ata_port *ap)
 	/* wait till EH commits suicide */
 	ata_port_wait_eh(ap);
 
-	/* it better be dead now */
+	/* It better be dead now and not have any remaining deferred qc. */
 	WARN_ON(!(ap->pflags & ATA_PFLAG_UNLOADED));
+	WARN_ON(ap->deferred_qc);
 
+	cancel_work_sync(&ap->deferred_qc_work);
 	cancel_delayed_work_sync(&ap->hotplug_task);
 	cancel_delayed_work_sync(&ap->scsi_rescan_task);
 
-- 
2.53.0