linux-kernel - Re: [PATCH 3/4 v2] ide: Implement disk shock protection support

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Message-ID: <87d4igqxlm.fsf@denkblock.local>
Date:	Sat, 04 Oct 2008 15:49:25 +0200
From:	Elias Oltmanns <eo@...ensachen.de>
To:	Bartlomiej Zolnierkiewicz <bzolnier@...il.com>
Cc:	linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4 v2] ide: Implement disk shock protection support

Elias Oltmanns <eo@...ensachen.de> wrote:
> Bartlomiej Zolnierkiewicz <bzolnier@...il.com> wrote:
>> On Wednesday 17 September 2008 09:38:37 Elias Oltmanns wrote:
>
>>> 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@...ensachen.de>
>>
>> applied
>
> Hi Bart,
>
> may I ask you to apply yet another inter-diff? This is in order to
> address three issues:
>
> 1. Make sure that no negative value is being passed to
>    jiffies_to_msecs() in ide_park_show().
> 2. Drop the superfluous variable hwif in ide_special_rq().
> 3. Skip initialisation of task and tf in ide_special_rq() if we are not
>    handling a (un)park request.

Well, #3 should have been done differently because we donn't want to
check for REQ_(UN)?PARK_HEADS more often than is necessary. Here is a
revised version of the inter-diff.

Regards,

Elias


Signed-off-by: Elias Oltmanns <eo@...ensachen.de>
---
diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c
index 09d10a5..77c6eae 100644
--- a/drivers/ide/ide-io.c
+++ b/drivers/ide/ide-io.c
@@ -672,25 +672,32 @@ EXPORT_SYMBOL_GPL(ide_devset_execute);
 
 static ide_startstop_t ide_special_rq(ide_drive_t *drive, struct request *rq)
 {
-	ide_hwif_t *hwif = drive->hwif;
-	ide_task_t task;
-	struct ide_taskfile *tf = &task.tf;
+	u8 cmd = rq->cmd[0];
+
+	if (cmd == REQ_PARK_HEADS || cmd == REQ_UNPARK_HEADS) {
+		ide_task_t task;
+		struct ide_taskfile *tf = &task.tf;
+
+		memset(&task, 0, sizeof(task));
+		if (cmd == REQ_PARK_HEADS) {
+			drive->sleep = *(unsigned long *)rq->special;
+			drive->dev_flags |= IDE_DFLAG_SLEEPING;
+			tf->command = ATA_CMD_IDLEIMMEDIATE;
+			tf->feature = 0x44;
+			tf->lbal = 0x4c;
+			tf->lbam = 0x4e;
+			tf->lbah = 0x55;
+			task.tf_flags |= IDE_TFLAG_CUSTOM_HANDLER;
+		} else		/* cmd == REQ_UNPARK_HEADS */
+			tf->command = ATA_CMD_CHK_POWER;
+
+		task.tf_flags |= IDE_TFLAG_TF | IDE_TFLAG_DEVICE;
+		task.rq = rq;
+		drive->hwif->data_phase = task.data_phase = TASKFILE_NO_DATA;
+		return do_rw_taskfile(drive, &task);
+	}
 
-	memset(&task, 0, sizeof(task));
-	switch (rq->cmd[0]) {
-	case REQ_PARK_HEADS:
-		drive->sleep = *(unsigned long *)rq->special;
-		drive->dev_flags |= IDE_DFLAG_SLEEPING;
-		tf->command = ATA_CMD_IDLEIMMEDIATE;
-		tf->feature = 0x44;
-		tf->lbal = 0x4c;
-		tf->lbam = 0x4e;
-		tf->lbah = 0x55;
-		task.tf_flags |= IDE_TFLAG_CUSTOM_HANDLER;
-		break;
-	case REQ_UNPARK_HEADS:
-		tf->command = ATA_CMD_CHK_POWER;
-		break;
+	switch (cmd) {
 	case REQ_DEVSET_EXEC:
 	{
 		int err, (*setfunc)(ide_drive_t *, int) = rq->special;
@@ -710,10 +717,6 @@ static ide_startstop_t ide_special_rq(ide_drive_t *drive, struct request *rq)
 		ide_end_request(drive, 0, 0);
 		return ide_stopped;
 	}
-	task.tf_flags |= IDE_TFLAG_TF | IDE_TFLAG_DEVICE;
-	task.rq = rq;
-	hwif->data_phase = task.data_phase = TASKFILE_NO_DATA;
-	return do_rw_taskfile(drive, &task);
 }
 
 static void ide_check_pm_state(ide_drive_t *drive, struct request *rq)
diff --git a/drivers/ide/ide-park.c b/drivers/ide/ide-park.c
index 35fc3ee..02d7e35 100644
--- a/drivers/ide/ide-park.c
+++ b/drivers/ide/ide-park.c
@@ -61,15 +61,17 @@ ssize_t ide_park_show(struct device *dev, struct device_attribute *attr,
 		      char *buf)
 {
 	ide_drive_t *drive = to_ide_device(dev);
+	unsigned long now;
 	unsigned int msecs;
 
 	if (drive->dev_flags & IDE_DFLAG_NO_UNLOAD)
 		return -EOPNOTSUPP;
 
 	spin_lock_irq(&ide_lock);
+	now = jiffies;
 	if (drive->dev_flags & IDE_DFLAG_PARKED &&
-	    time_after(drive->sleep, jiffies))
-		msecs = jiffies_to_msecs(drive->sleep - jiffies);
+	    time_after(drive->sleep, now))
+		msecs = jiffies_to_msecs(drive->sleep - now);
 	else
 		msecs = 0;
 	spin_unlock_irq(&ide_lock);
--
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