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| author | Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> | 2007-03-26 23:03:19 +0200 |
|---|---|---|
| committer | Bartlomiej Zolnierkiewicz <bzolnier@gmail.com> | 2007-03-26 23:03:19 +0200 |
| commit | 8799620400b0b1a4729d8be828b5bfb3d2a8db1a (patch) | |
| tree | 4c5f3bb3360dddcc9638c4e92ddb7f1f2e0b1578 /drivers | |
| parent | f68d9320cd06fdec19735143b42e5197b63165b4 (diff) | |
| download | linux-8799620400b0b1a4729d8be828b5bfb3d2a8db1a.tar.gz linux-8799620400b0b1a4729d8be828b5bfb3d2a8db1a.tar.bz2 linux-8799620400b0b1a4729d8be828b5bfb3d2a8db1a.zip | |
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 <sshtylyov@ru.mvista.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/ide/ide.c | 37 |
1 files changed, 30 insertions, 7 deletions
diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c index 695610f0e3e4..a6f098fda884 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 |