Elias Oltmanns <eo@xxxxxxxxxxxxxx> wrote:
> From: Elias Oltmanns <eo@xxxxxxxxxxxxxx>
> Subject: [PATCH] ide: Implement disk shock protection support
>
> On user request (through sysfs), the IDLE IMMEDIATE command with UNLOAD
> FEATURE as specified in ATA-7 is issued to the device and processing of
> the request queue is stopped thereafter until the specified timeout
> expires or user space asks to resume normal operation. This is supposed
> to prevent the heads of a hard drive from accidentally crashing onto the
> platter when a heavy shock is anticipated (like a falling laptop expected
> to hit the floor). Port resets are deferred whenever a device on that
> port is in the parked state.
>
> Signed-off-by: Elias Oltmanns <eo@xxxxxxxxxxxxxx>
> ---
[...]
> diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
> index 91182eb..ea75c71 100644
> --- a/drivers/ide/ide-iops.c
> +++ b/drivers/ide/ide-iops.c
> @@ -1079,12 +1079,13 @@ static void pre_reset(ide_drive_t *drive)
> static ide_startstop_t do_reset1 (ide_drive_t *drive, int do_not_try_atapi)
> {
> unsigned int unit;
> - unsigned long flags;
> + unsigned long flags, timeout;
> ide_hwif_t *hwif;
> ide_hwgroup_t *hwgroup;
> struct ide_io_ports *io_ports;
> const struct ide_tp_ops *tp_ops;
> const struct ide_port_ops *port_ops;
> + DEFINE_WAIT(wait);
>
> spin_lock_irqsave(&ide_lock, flags);
> hwif = HWIF(drive);
> @@ -1111,6 +1112,30 @@ static ide_startstop_t do_reset1 (ide_drive_t *drive, int do_not_try_atapi)
> return ide_started;
> }
>
> + /* We must not disturb devices in the IDE_DFLAG_PARKED state. */
> + do {
> + unsigned long now;
> + int i;
> +
> + timeout = jiffies;
> + for (i = 0; i < MAX_DRIVES; i++) {
> + ide_drive_t *tdrive = &hwif->drives[i];
> +
> + if (tdrive->dev_flags & IDE_DFLAG_PRESENT &&
> + tdrive->dev_flags & IDE_DFLAG_PARKED &&
> + time_after(tdrive->sleep, timeout))
> + timeout = tdrive->sleep;
> + }
> +
> + now = jiffies;
> + if (time_before_eq(timeout, now))
> + break;
> +
> + prepare_to_wait(&ide_park_wq, &wait, TASK_UNINTERRUPTIBLE);
> + timeout = schedule_timeout_uninterruptible(timeout - now);
It has occurred to me that something is wrong here after all: we need to
release the lock before sleeping. I'll change that to
spin_unlock_irqrestore(&ide_lock, flags);
prepare_to_wait(&ide_park_wq, &wait, TASK_UNINTERRUPTIBLE);
timeout = schedule_timeout_uninterruptible(timeout - now);
spin_lock_irqsave(&ide_lock, flags);
> + } while (timeout);
> + finish_wait(&ide_park_wq, &wait);
> +
> /*
> * First, reset any device state data we were maintaining
> * for any of the drives on this interface.
Hopefully, this meets with your approval. I'll send out the updated
patch series shortly. Even though this is a minor change, I don't feel
comfortable with adding your Acked-by myself now, so please ack the new
patch.
Regards,
Elias
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