From: Jens Axboe <axboe@suse.de>
2.6 breaks really really easily if you have any traffic on a device and
issue a hdparm (or similar) command to it. Things like set_using_dma() and
ide_set_xfer_rate() just stomp all over the drive regardless of what it's
doing right now.
I hacked something up for the SUSE kernel to fix this _almost_, it still
doesn't handle cases where you want to serialize across more than a single
channel. Not a common case, but I think there is such hardware out there
(which?).
Clearly something needs to be done about this, it's extremely frustrating
not to be able to reliably turn on dma on a drive at all. I'm just tossing
this one out there to solve 99% of the case, I'd like some input from you
on what you feel we should do.
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/drivers/ide/ide-io.c | 40 ++++++++++++++++++++++++++++++++++++++++
25-akpm/drivers/ide/ide-lib.c | 10 +++++++---
25-akpm/drivers/ide/ide.c | 22 ++++++++++++++++------
25-akpm/include/linux/ide.h | 2 ++
4 files changed, 65 insertions(+), 9 deletions(-)
diff -puN drivers/ide/ide.c~serialize-access-to-ide-devices drivers/ide/ide.c
--- 25/drivers/ide/ide.c~serialize-access-to-ide-devices 2005-02-22 18:16:47.000000000 -0800
+++ 25-akpm/drivers/ide/ide.c 2005-02-22 18:16:47.000000000 -0800
@@ -1220,18 +1220,28 @@ static int set_io_32bit(ide_drive_t *dri
static int set_using_dma (ide_drive_t *drive, int arg)
{
#ifdef CONFIG_BLK_DEV_IDEDMA
+ int ret = -EPERM;
+
+ ide_pin_hwgroup(drive);
+
if (!drive->id || !(drive->id->capability & 1))
- return -EPERM;
+ goto out;
if (HWIF(drive)->ide_dma_check == NULL)
- return -EPERM;
+ goto out;
+ ret = -EIO;
if (arg) {
- if (HWIF(drive)->ide_dma_check(drive)) return -EIO;
- if (HWIF(drive)->ide_dma_on(drive)) return -EIO;
+ if (HWIF(drive)->ide_dma_check(drive))
+ goto out;
+ if (HWIF(drive)->ide_dma_on(drive))
+ goto out;
} else {
if (__ide_dma_off(drive))
- return -EIO;
+ goto out;
}
- return 0;
+ ret = 0;
+out:
+ ide_unpin_hwgroup(drive);
+ return ret;
#else
return -EPERM;
#endif
diff -puN drivers/ide/ide-io.c~serialize-access-to-ide-devices drivers/ide/ide-io.c
--- 25/drivers/ide/ide-io.c~serialize-access-to-ide-devices 2005-02-22 18:16:47.000000000 -0800
+++ 25-akpm/drivers/ide/ide-io.c 2005-02-22 18:16:47.000000000 -0800
@@ -1127,6 +1127,46 @@ void ide_stall_queue (ide_drive_t *drive
drive->sleeping = 1;
}
+void ide_unpin_hwgroup(ide_drive_t *drive)
+{
+ ide_hwgroup_t *hwgroup = HWGROUP(drive);
+
+ if (hwgroup) {
+ spin_lock_irq(&ide_lock);
+ HWGROUP(drive)->busy = 0;
+ drive->blocked = 0;
+ do_ide_request(drive->queue);
+ spin_unlock_irq(&ide_lock);
+ }
+}
+
+void ide_pin_hwgroup(ide_drive_t *drive)
+{
+ ide_hwgroup_t *hwgroup = HWGROUP(drive);
+
+ /*
+ * should only happen very early, so not a problem
+ */
+ if (!hwgroup)
+ return;
+
+ spin_lock_irq(&ide_lock);
+ do {
+ if (!hwgroup->busy && !drive->blocked && !drive->doing_barrier)
+ break;
+ spin_unlock_irq(&ide_lock);
+ schedule_timeout(HZ/100);
+ spin_lock_irq(&ide_lock);
+ } while (hwgroup->busy || drive->blocked || drive->doing_barrier);
+
+ /*
+ * we've now secured exclusive access to this hwgroup
+ */
+ hwgroup->busy = 1;
+ drive->blocked = 1;
+ spin_unlock_irq(&ide_lock);
+}
+
EXPORT_SYMBOL(ide_stall_queue);
#define WAKEUP(drive) ((drive)->service_start + 2 * (drive)->service_time)
diff -puN drivers/ide/ide-lib.c~serialize-access-to-ide-devices drivers/ide/ide-lib.c
--- 25/drivers/ide/ide-lib.c~serialize-access-to-ide-devices 2005-02-22 18:16:47.000000000 -0800
+++ 25-akpm/drivers/ide/ide-lib.c 2005-02-22 18:16:47.000000000 -0800
@@ -434,13 +434,17 @@ void ide_toggle_bounce(ide_drive_t *driv
int ide_set_xfer_rate(ide_drive_t *drive, u8 rate)
{
+ int ret;
#ifndef CONFIG_BLK_DEV_IDEDMA
rate = min(rate, (u8) XFER_PIO_4);
#endif
- if(HWIF(drive)->speedproc)
- return HWIF(drive)->speedproc(drive, rate);
+ ide_pin_hwgroup(drive);
+ if (HWIF(drive)->speedproc)
+ ret = HWIF(drive)->speedproc(drive, rate);
else
- return -1;
+ ret = -1;
+ ide_unpin_hwgroup(drive);
+ return ret;
}
EXPORT_SYMBOL_GPL(ide_set_xfer_rate);
diff -puN include/linux/ide.h~serialize-access-to-ide-devices include/linux/ide.h
--- 25/include/linux/ide.h~serialize-access-to-ide-devices 2005-02-22 18:16:47.000000000 -0800
+++ 25-akpm/include/linux/ide.h 2005-02-22 18:16:47.000000000 -0800
@@ -1321,6 +1321,8 @@ ide_startstop_t __ide_do_rw_disk(ide_dri
* to the hwgroup by sleeping for timeout jiffies.
*/
extern void ide_stall_queue(ide_drive_t *drive, unsigned long timeout);
+extern void ide_pin_hwgroup(ide_drive_t *);
+extern void ide_unpin_hwgroup(ide_drive_t *);
extern int ide_spin_wait_hwgroup(ide_drive_t *);
extern void ide_timer_expiry(unsigned long);
_