[PATCH] libata: implement ata_poll_qc_complete and use it in polling functions
[PATCH libata-dev-2.6:upstream] implement ata_poll_qc_complete and use it in polling functions
Previously, libata polling functions turned irq back on and completed
qc commands without holding host lock. This creates a race condition
between the polling task and interrupts from other ports on the same
host set or spurious interrupt from itself.
This patch implements ata_poll_qc_complete which enables irq and
completes qc atomically and convert all polling functions.
Note: atapi_packet_task() didn't use to turn irq back on or clear
ATA_FLAG_NOINTR on error exits. This patch makes it use
ata_poll_qc_complete which does both.
Note: With this change, ALL invocations of ata_qc_complete() are now
done under host_set lock.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index c92439f..2f68563 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -2402,6 +2402,26 @@
}
/**
+ * ata_poll_qc_complete - turn irq back on and finish qc
+ * @qc: Command to complete
+ * @drv_stat: ATA status register content
+ *
+ * LOCKING:
+ * None. (grabs host lock)
+ */
+
+void ata_poll_qc_complete(struct ata_queued_cmd *qc, u8 drv_stat)
+{
+ struct ata_port *ap = qc->ap;
+
+ spin_lock_irq(&ap->host_set->lock);
+ ap->flags &= ~ATA_FLAG_NOINTR;
+ ata_irq_on(ap);
+ ata_qc_complete(qc, drv_stat);
+ spin_unlock_irq(&ap->host_set->lock);
+}
+
+/**
* ata_pio_poll -
* @ap:
*
@@ -2492,9 +2512,7 @@
ap->pio_task_state = PIO_ST_IDLE;
- ata_irq_on(ap);
-
- ata_qc_complete(qc, drv_stat);
+ ata_poll_qc_complete(qc, drv_stat);
}
@@ -2844,9 +2862,7 @@
if ((status & ATA_DRQ) == 0) {
ap->pio_task_state = PIO_ST_IDLE;
- ata_irq_on(ap);
-
- ata_qc_complete(qc, status);
+ ata_poll_qc_complete(qc, status);
return;
}
@@ -2876,9 +2892,7 @@
ap->pio_task_state = PIO_ST_IDLE;
- ata_irq_on(ap);
-
- ata_qc_complete(qc, drv_stat | ATA_ERR);
+ ata_poll_qc_complete(qc, drv_stat | ATA_ERR);
}
static void ata_pio_task(void *_data)
@@ -3791,7 +3805,7 @@
return;
err_out:
- ata_qc_complete(qc, ATA_ERR);
+ ata_poll_qc_complete(qc, ATA_ERR);
}