Commit 6c3c3158 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

IDE: Make taskfile interface more robust wrt unexpected end-of-command 



Now that we handle all the special commands using REQ_TYPE_ATA_TASKFILE
rather than using the old REQ_TYPE_ATA_CMD model, we need to also
emulate the lack of full taskfile data that comes with the old command
model (ie when commands are generated with the HDIO_DRIVE_CMD ioctl
rather than using the HDIO_DRIVE_TASK[FILE] ioctls).

In particular, this means that we should handle command completion the
more relaxed way that the old drive_cmd_intr() code did.  It allows
commands to finish early even if they don't use up all the data that we
thought we had for them.

This fixes a regression seen by Anders Eriksson where some SMART
commands sent by smartd would cause a boot-time system hang on his
machine because the IDE command handling code didn't realize that the
command had completed.

Tested-by: default avatarAnders Eriksson <aeriksson@fastmail.fm>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: default avatarBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d5eee405

drivers/ide/ide-taskfile.c

+27 −9
Original line number Diff line number Diff line
@@ -422,6 +422,25 @@ void task_end_request(ide_drive_t *drive, struct request *rq, u8 stat) 
		ide_end_request(drive, 1, rq->nr_sectors);

}



/*

 * We got an interrupt on a task_in case, but no errors and no DRQ.

 *

 * It might be a spurious irq (shared irq), but it might be a

 * command that had no output.

 */

static ide_startstop_t task_in_unexpected(ide_drive_t *drive, struct request *rq, u8 stat)

{

	/* Command all done? */

	if (OK_STAT(stat, READY_STAT, BUSY_STAT)) {

		task_end_request(drive, rq, stat);

		return ide_stopped;

	}



	/* Assume it was a spurious irq */

	ide_set_handler(drive, &task_in_intr, WAIT_WORSTCASE, NULL);

	return ide_started;

}



/*

 * Handler for command with PIO data-in phase (Read/Read Multiple).

 */
@@ -431,18 +450,17 @@ static ide_startstop_t task_in_intr(ide_drive_t *drive) 
	struct request *rq = HWGROUP(drive)->rq;

	u8 stat = ide_read_status(drive);



	/* new way for dealing with premature shared PCI interrupts */

	if (!OK_STAT(stat, DRQ_STAT, BAD_R_STAT)) {

		if (stat & (ERR_STAT | DRQ_STAT))

	/* Error? */

	if (stat & ERR_STAT)

		return task_error(drive, rq, __FUNCTION__, stat);

		/* No data yet, so wait for another IRQ. */

		ide_set_handler(drive, &task_in_intr, WAIT_WORSTCASE, NULL);

		return ide_started;

	}



	/* Didn't want any data? Odd. */

	if (!(stat & DRQ_STAT))

		return task_in_unexpected(drive, rq, stat);



	ide_pio_datablock(drive, rq, 0);



	/* If it was the last datablock check status and finish transfer. */

	/* Are we done? Check status and finish transfer. */

	if (!hwif->nleft) {

		stat = wait_drive_not_busy(drive);

		if (!OK_STAT(stat, 0, BAD_STAT))

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