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Commit 40e8c82c authored by Tejun Heo's avatar Tejun Heo Committed by Jeff Garzik
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[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: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarJeff Garzik <jgarzik@pobox.com>
parent c1389503

drivers/scsi/libata-core.c

+24 −10
Original line number Diff line number Diff line
@@ -2401,6 +2401,26 @@ static int ata_sg_setup(struct ata_queued_cmd *qc) 
	return 0;

}



/**

 *	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 @@ static void ata_pio_complete (struct ata_port *ap) 


	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 @@ static void ata_pio_block(struct ata_port *ap) 
		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 @@ static void ata_pio_error(struct ata_port *ap) 


	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 @@ static void atapi_packet_task(void *_data) 
	return;



err_out:

	ata_qc_complete(qc, ATA_ERR);

	ata_poll_qc_complete(qc, ATA_ERR);

}