Commit f686bcb8 authored by Tejun Heo's avatar Tejun Heo
Browse files

[PATCH] libata-eh-fw: implement new EH scheduling via error completion 



There are several ways a qc can get schedule for EH in new EH.  This
patch implements one of them - completing a qc with ATA_QCFLAG_FAILED
set or with non-zero qc->err_mask.  ALL such qc's are examined by EH.

New EH schedules a qc for EH from completion iff ->error_handler is
implemented, qc is marked as failed or qc->err_mask is non-zero and
the command is not an internal command (internal cmd is handled via
->post_internal_cmd).  The EH scheduling itself is performed by asking
SCSI midlayer to schedule EH for the specified scmd.

For drivers implementing old-EH, nothing changes.  As this change
makes ata_qc_complete() rather large, it's not inlined anymore and
__ata_qc_complete() is exported to other parts of libata for later
use.

Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
parent f69499f4

drivers/scsi/libata-core.c

+61 −1
Original line number Diff line number Diff line
@@ -4123,6 +4123,66 @@ void __ata_qc_complete(struct ata_queued_cmd *qc) 
	qc->complete_fn(qc);

}



/**

 *	ata_qc_complete - Complete an active ATA command

 *	@qc: Command to complete

 *	@err_mask: ATA Status register contents

 *

 *	Indicate to the mid and upper layers that an ATA

 *	command has completed, with either an ok or not-ok status.

 *

 *	LOCKING:

 *	spin_lock_irqsave(host_set lock)

 */

void ata_qc_complete(struct ata_queued_cmd *qc)

{

	struct ata_port *ap = qc->ap;



	/* XXX: New EH and old EH use different mechanisms to

	 * synchronize EH with regular execution path.

	 *

	 * In new EH, a failed qc is marked with ATA_QCFLAG_FAILED.

	 * Normal execution path is responsible for not accessing a

	 * failed qc.  libata core enforces the rule by returning NULL

	 * from ata_qc_from_tag() for failed qcs.

	 *

	 * Old EH depends on ata_qc_complete() nullifying completion

	 * requests if ATA_QCFLAG_EH_SCHEDULED is set.  Old EH does

	 * not synchronize with interrupt handler.  Only PIO task is

	 * taken care of.

	 */

	if (ap->ops->error_handler) {

		WARN_ON(ap->flags & ATA_FLAG_FROZEN);



		if (unlikely(qc->err_mask))

			qc->flags |= ATA_QCFLAG_FAILED;



		if (unlikely(qc->flags & ATA_QCFLAG_FAILED)) {

			if (!ata_tag_internal(qc->tag)) {

				/* always fill result TF for failed qc */

				ap->ops->tf_read(ap, &qc->result_tf);

				ata_qc_schedule_eh(qc);

				return;

			}

		}



		/* read result TF if requested */

		if (qc->flags & ATA_QCFLAG_RESULT_TF)

			ap->ops->tf_read(ap, &qc->result_tf);



		__ata_qc_complete(qc);

	} else {

		if (qc->flags & ATA_QCFLAG_EH_SCHEDULED)

			return;



		/* read result TF if failed or requested */

		if (qc->err_mask || qc->flags & ATA_QCFLAG_RESULT_TF)

			ap->ops->tf_read(ap, &qc->result_tf);



		__ata_qc_complete(qc);

	}

}



static inline int ata_should_dma_map(struct ata_queued_cmd *qc)

{

	struct ata_port *ap = qc->ap;
@@ -5245,7 +5305,7 @@ EXPORT_SYMBOL_GPL(ata_device_add); 
EXPORT_SYMBOL_GPL(ata_host_set_remove);

EXPORT_SYMBOL_GPL(ata_sg_init);

EXPORT_SYMBOL_GPL(ata_sg_init_one);

EXPORT_SYMBOL_GPL(__ata_qc_complete);

EXPORT_SYMBOL_GPL(ata_qc_complete);

EXPORT_SYMBOL_GPL(ata_qc_issue_prot);

EXPORT_SYMBOL_GPL(ata_tf_load);

EXPORT_SYMBOL_GPL(ata_tf_read);

drivers/scsi/libata-eh.c

+27 −0
Original line number Diff line number Diff line
@@ -210,6 +210,33 @@ void ata_eng_timeout(struct ata_port *ap) 
	DPRINTK("EXIT\n");

}



/**

 *	ata_qc_schedule_eh - schedule qc for error handling

 *	@qc: command to schedule error handling for

 *

 *	Schedule error handling for @qc.  EH will kick in as soon as

 *	other commands are drained.

 *

 *	LOCKING:

 *	spin_lock_irqsave(host_set lock)

 */

void ata_qc_schedule_eh(struct ata_queued_cmd *qc)

{

	struct ata_port *ap = qc->ap;



	WARN_ON(!ap->ops->error_handler);



	qc->flags |= ATA_QCFLAG_FAILED;

	qc->ap->flags |= ATA_FLAG_EH_PENDING;



	/* The following will fail if timeout has already expired.

	 * ata_scsi_error() takes care of such scmds on EH entry.

	 * Note that ATA_QCFLAG_FAILED is unconditionally set after

	 * this function completes.

	 */

	scsi_req_abort_cmd(qc->scsicmd);

}



static void ata_eh_scsidone(struct scsi_cmnd *scmd)

{

	/* nada */

drivers/scsi/libata.h

+2 −0
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ extern int ata_do_reset(struct ata_port *ap, ata_reset_fn_t reset, 
			unsigned int *classes);

extern void ata_qc_free(struct ata_queued_cmd *qc);

extern void ata_qc_issue(struct ata_queued_cmd *qc);

extern void __ata_qc_complete(struct ata_queued_cmd *qc);

extern int ata_check_atapi_dma(struct ata_queued_cmd *qc);

extern void ata_dev_select(struct ata_port *ap, unsigned int device,

                           unsigned int wait, unsigned int can_sleep);
@@ -101,5 +102,6 @@ extern void ata_scsi_rbuf_fill(struct ata_scsi_args *args, 
/* libata-eh.c */

extern enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd);

extern void ata_scsi_error(struct Scsi_Host *host);

extern void ata_qc_schedule_eh(struct ata_queued_cmd *qc);



#endif /* __LIBATA_H__ */

include/linux/libata.h

+1 −26
Original line number Diff line number Diff line
@@ -605,7 +605,7 @@ extern void ata_bmdma_start (struct ata_queued_cmd *qc); 
extern void ata_bmdma_stop(struct ata_queued_cmd *qc);

extern u8   ata_bmdma_status(struct ata_port *ap);

extern void ata_bmdma_irq_clear(struct ata_port *ap);

extern void __ata_qc_complete(struct ata_queued_cmd *qc);

extern void ata_qc_complete(struct ata_queued_cmd *qc);

extern void ata_scsi_simulate(struct ata_device *dev, struct scsi_cmnd *cmd,

			      void (*done)(struct scsi_cmnd *));

extern int ata_std_bios_param(struct scsi_device *sdev,
@@ -882,31 +882,6 @@ static inline void ata_qc_reinit(struct ata_queued_cmd *qc) 
	qc->result_tf.feature = 0;

}



/**

 *	ata_qc_complete - Complete an active ATA command

 *	@qc: Command to complete

 *	@err_mask: ATA Status register contents

 *

 *	Indicate to the mid and upper layers that an ATA

 *	command has completed, with either an ok or not-ok status.

 *

 *	LOCKING:

 *	spin_lock_irqsave(host_set lock)

 */

static inline void ata_qc_complete(struct ata_queued_cmd *qc)

{

	struct ata_port *ap = qc->ap;



	if (unlikely(qc->flags & ATA_QCFLAG_EH_SCHEDULED))

		return;



	/* read result TF if failed or requested */

	if (qc->err_mask || qc->flags & ATA_QCFLAG_RESULT_TF)

		ap->ops->tf_read(ap, &qc->result_tf);



	__ata_qc_complete(qc);

}



/**

 *	ata_irq_on - Enable interrupts on a port.

 *	@ap: Port on which interrupts are enabled.