From 8799620400b0b1a4729d8be828b5bfb3d2a8db1a Mon Sep 17 00:00:00 2001 From: Bartlomiej Zolnierkiewicz Date: Mon, 26 Mar 2007 23:03:19 +0200 Subject: ide: fix locking for manual DMA enable/disable ("hdparm -d") Since hwif->ide_dma_check and hwif->ide_dma_on never queue any commands (ide_config_drive_speed() sets transfer mode using polling and has no error recovery) we are safe with setting hwgroup->busy for the time while DMA setting for a drive is changed (so it won't race against I/O commands in fly). I audited briefly all ->ide_dma_check/->ide_dma_on/->tuneproc/->speedproc implementations and they all look OK wrt to this change. This patch finally allowed me to close kernel bugzilla bug #8169 (once again thanks to Patrick Horn for reporting the issue & testing patches). Cc: Sergei Shtylyov Cc: Alan Cox Signed-off-by: Bartlomiej Zolnierkiewicz --- drivers/ide/ide.c | 37 ++++++++++++++++++++++++++++++------- 1 file changed, 30 insertions(+), 7 deletions(-) (limited to 'drivers') diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c index 695610f0e3e..a6f098fda88 100644 --- a/drivers/ide/ide.c +++ b/drivers/ide/ide.c @@ -1124,17 +1124,40 @@ static int set_io_32bit(ide_drive_t *drive, int arg) static int set_using_dma (ide_drive_t *drive, int arg) { #ifdef CONFIG_BLK_DEV_IDEDMA + ide_hwif_t *hwif = drive->hwif; + int err = -EPERM; + if (!drive->id || !(drive->id->capability & 1)) - return -EPERM; - if (HWIF(drive)->ide_dma_check == NULL) - return -EPERM; + goto out; + + if (hwif->ide_dma_check == NULL) + goto out; + + err = -EBUSY; + if (ide_spin_wait_hwgroup(drive)) + goto out; + /* + * set ->busy flag, unlock and let it ride + */ + hwif->hwgroup->busy = 1; + spin_unlock_irq(&ide_lock); + + err = 0; + if (arg) { - if (ide_set_dma(drive)) - return -EIO; - if (HWIF(drive)->ide_dma_on(drive)) return -EIO; + if (ide_set_dma(drive) || hwif->ide_dma_on(drive)) + err = -EIO; } else ide_dma_off(drive); - return 0; + + /* + * lock, clear ->busy flag and unlock before leaving + */ + spin_lock_irq(&ide_lock); + hwif->hwgroup->busy = 0; + spin_unlock_irq(&ide_lock); +out: + return err; #else return -EPERM; #endif -- cgit v1.2.3