[PATCH] libata: improve EH action and EHI flag handling

Update ata_eh_about_to_do() and ata_eh_done() to improve EH action and
EHI flag handling.

* There are two types of EHI flags - one which expires on successful
EH and the other which expires on a successful reset. Make this
distinction clear.

* Unlike other EH actions, reset actions are represented by two EH
action masks and a EHI modifier. Implement correct about_to_do/done
semantics for resets. That is, prior to reset, related EH info is
sucked in from ehi and cleared, and after reset is complete, related
EH info in ehc is cleared.

These changes improve consistency and remove unnecessary EH actions
caused by stale EH action masks and EHI flags.

Signed-off-by: Tejun Heo <[e-mail]>
Signed-off-by: Jeff Garzik <[e-mail]>

drivers/scsi/libata-eh.c

···
 			       unsigned int action)
 {
 	unsigned long flags;
+	struct ata_eh_info *ehi = &ap->eh_info;
+	struct ata_eh_context *ehc = &ap->eh_context;
 
 	spin_lock_irqsave(ap->lock, flags);
 
-	ata_eh_clear_action(dev, &ap->eh_info, action);
+	/* Reset is represented by combination of actions and EHI
+	 * flags.  Suck in all related bits before clearing eh_info to
+	 * avoid losing requested action.
+	 */
+	if (action & ATA_EH_RESET_MASK) {
+		ehc->i.action |= ehi->action & ATA_EH_RESET_MASK;
+		ehc->i.flags |= ehi->flags & ATA_EHI_RESET_MODIFIER_MASK;
 
-	if (!(ap->eh_context.i.flags & ATA_EHI_QUIET))
+		/* make sure all reset actions are cleared & clear EHI flags */
+		action |= ATA_EH_RESET_MASK;
+		ehi->flags &= ~ATA_EHI_RESET_MODIFIER_MASK;
+	}
+
+	ata_eh_clear_action(dev, ehi, action);
+
+	if (!(ehc->i.flags & ATA_EHI_QUIET))
 		ap->pflags |= ATA_PFLAG_RECOVERED;
 
 	spin_unlock_irqrestore(ap->lock, flags);
···
 static void ata_eh_done(struct ata_port *ap, struct ata_device *dev,
 			unsigned int action)
 {
+	/* if reset is complete, clear all reset actions & reset modifier */
+	if (action & ATA_EH_RESET_MASK) {
+		action |= ATA_EH_RESET_MASK;
+		ap->eh_context.i.flags &= ~ATA_EHI_RESET_MODIFIER_MASK;
+	}
+
 	ata_eh_clear_action(dev, &ap->eh_context.i, action);
 }
 
···
 	ata_reset_fn_t reset;
 	int i, did_followup_srst, rc;
 
+	/* about to reset */
+	ata_eh_about_to_do(ap, NULL, ehc->i.action & ATA_EH_RESET_MASK);
+
 	/* Determine which reset to use and record in ehc->i.action.
 	 * prereset() may examine and modify it.
 	 */
···
 		ata_port_printk(ap, KERN_INFO, "%s resetting port\n",
 				reset == softreset ? "soft" : "hard");
 
-	/* reset */
-	ata_eh_about_to_do(ap, NULL, ATA_EH_RESET_MASK);
+	/* mark that this EH session started with reset */
 	ehc->i.flags |= ATA_EHI_DID_RESET;
 
 	rc = ata_do_reset(ap, reset, classes);
···
 			postreset(ap, classes);
 
 		/* reset successful, schedule revalidation */
-		ata_eh_done(ap, NULL, ATA_EH_RESET_MASK);
+		ata_eh_done(ap, NULL, ehc->i.action & ATA_EH_RESET_MASK);
 		ehc->i.action |= ATA_EH_REVALIDATE;
 	}
 

include/linux/libata.h

···
 
 	/* ata_eh_info->flags */
 	ATA_EHI_HOTPLUGGED	= (1 << 0),  /* could have been hotplugged */
-	ATA_EHI_RESUME_LINK	= (1 << 1),  /* need to resume link */
+	ATA_EHI_RESUME_LINK	= (1 << 1),  /* resume link (reset modifier) */
 	ATA_EHI_NO_AUTOPSY	= (1 << 2),  /* no autopsy */
 	ATA_EHI_QUIET		= (1 << 3),  /* be quiet */
 
 	ATA_EHI_DID_RESET	= (1 << 16), /* already reset this port */
+
+	ATA_EHI_RESET_MODIFIER_MASK = ATA_EHI_RESUME_LINK,
 
 	/* max repeat if error condition is still set after ->error_handler */
 	ATA_EH_MAX_REPEAT	= 5,