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authorBartlomiej Zolnierkiewicz <bzolnier@gmail.com>2007-03-26 23:03:19 +0200
committerBartlomiej Zolnierkiewicz <bzolnier@gmail.com>2007-03-26 23:03:19 +0200
commit8799620400b0b1a4729d8be828b5bfb3d2a8db1a (patch)
tree4c5f3bb3360dddcc9638c4e92ddb7f1f2e0b1578 /drivers
parentf68d9320cd06fdec19735143b42e5197b63165b4 (diff)
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.c37
1 files changed, 30 insertions, 7 deletions
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