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Commit 7dfdc9a5 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by James Bottomley
Browse files

[SCSI] use a completion in scsi_send_eh_cmnd 



scsi_send_eh_cmnd currently uses a semaphore and an overload of eh_timer
to either get a completion for a command for a timeout.
Switch to using a completion and wait_for_completion_timeout to simply
the code and not having to deal with the races ourselves.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent 262eef66

drivers/scsi/scsi_error.c

+29 −78
Original line number Diff line number Diff line
@@ -416,44 +416,16 @@ static int scsi_eh_completed_normally(struct scsi_cmnd *scmd) 
	return FAILED;

}



/**

 * scsi_eh_times_out - timeout function for error handling.

 * @scmd:	Cmd that is timing out.

 *

 * Notes:

 *    During error handling, the kernel thread will be sleeping waiting

 *    for some action to complete on the device.  our only job is to

 *    record that it timed out, and to wake up the thread.

 **/

static void scsi_eh_times_out(struct scsi_cmnd *scmd)

{

	scmd->eh_eflags |= SCSI_EH_REC_TIMEOUT;

	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd:%p\n", __FUNCTION__,

					  scmd));



	up(scmd->device->host->eh_action);

}



/**

 * scsi_eh_done - Completion function for error handling.

 * @scmd:	Cmd that is done.

 **/

static void scsi_eh_done(struct scsi_cmnd *scmd)

{

	/*

	 * if the timeout handler is already running, then just set the

	 * flag which says we finished late, and return.  we have no

	 * way of stopping the timeout handler from running, so we must

	 * always defer to it.

	 */

	if (del_timer(&scmd->eh_timeout)) {

		scmd->request->rq_status = RQ_SCSI_DONE;



		SCSI_LOG_ERROR_RECOVERY(3, printk("%s scmd: %p result: %x\n",

	SCSI_LOG_ERROR_RECOVERY(3,

		printk("%s scmd: %p result: %x\n",

			__FUNCTION__, scmd, scmd->result));



		up(scmd->device->host->eh_action);

	}

	complete(scmd->device->host->eh_action);

}



/**
@@ -461,10 +433,6 @@ static void scsi_eh_done(struct scsi_cmnd *scmd) 
 * @scmd:	SCSI Cmd to send.

 * @timeout:	Timeout for cmd.

 *

 * Notes:

 *    The initialization of the structures is quite a bit different in

 *    this case, and furthermore, there is a different completion handler

 *    vs scsi_dispatch_cmd.

 * Return value:

 *    SUCCESS or FAILED or NEEDS_RETRY

 **/
@@ -472,24 +440,16 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, int timeout) 
{

	struct scsi_device *sdev = scmd->device;

	struct Scsi_Host *shost = sdev->host;

	DECLARE_MUTEX_LOCKED(sem);

	DECLARE_COMPLETION(done);

	unsigned long timeleft;

	unsigned long flags;

	int rtn = SUCCESS;

	int rtn;



	/*

	 * we will use a queued command if possible, otherwise we will

	 * emulate the queuing and calling of completion function ourselves.

	 */

	if (sdev->scsi_level <= SCSI_2)

		scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |

			(sdev->lun << 5 & 0xe0);



	scsi_add_timer(scmd, timeout, scsi_eh_times_out);



	/*

	 * set up the semaphore so we wait for the command to complete.

	 */

	shost->eh_action = &sem;

	shost->eh_action = &done;

	scmd->request->rq_status = RQ_SCSI_BUSY;



	spin_lock_irqsave(shost->host_lock, flags);
@@ -497,47 +457,29 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, int timeout) 
	shost->hostt->queuecommand(scmd, scsi_eh_done);

	spin_unlock_irqrestore(shost->host_lock, flags);



	down(&sem);

	scsi_log_completion(scmd, SUCCESS);

	timeleft = wait_for_completion_timeout(&done, timeout);



	scmd->request->rq_status = RQ_SCSI_DONE;

	shost->eh_action = NULL;



	/*

	 * see if timeout.  if so, tell the host to forget about it.

	 * in other words, we don't want a callback any more.

	 */

	if (scmd->eh_eflags & SCSI_EH_REC_TIMEOUT) {

		scmd->eh_eflags &= ~SCSI_EH_REC_TIMEOUT;



		/*

		 * as far as the low level driver is

		 * concerned, this command is still active, so

		 * we must give the low level driver a chance

		 * to abort it. (db) 

		 *

		 * FIXME(eric) - we are not tracking whether we could

		 * abort a timed out command or not.  not sure how

		 * we should treat them differently anyways.

		 */

		if (shost->hostt->eh_abort_handler)

			shost->hostt->eh_abort_handler(scmd);

			

		scmd->request->rq_status = RQ_SCSI_DONE;

		rtn = FAILED;

	}

	scsi_log_completion(scmd, SUCCESS);



	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd: %p, rtn:%x\n",

					  __FUNCTION__, scmd, rtn));

	SCSI_LOG_ERROR_RECOVERY(3,

		printk("%s: scmd: %p, timeleft: %ld\n",

			__FUNCTION__, scmd, timeleft));



	/*

	 * now examine the actual status codes to see whether the command

	 * actually did complete normally.

	 * If there is time left scsi_eh_done got called, and we will

	 * examine the actual status codes to see whether the command

	 * actually did complete normally, else tell the host to forget

	 * about this command.

	 */

	if (rtn == SUCCESS) {

	if (timeleft) {

		rtn = scsi_eh_completed_normally(scmd);

		SCSI_LOG_ERROR_RECOVERY(3,

			printk("%s: scsi_eh_completed_normally %x\n",

			       __FUNCTION__, rtn));



		switch (rtn) {

		case SUCCESS:

		case NEEDS_RETRY:
@@ -547,6 +489,15 @@ static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, int timeout) 
			rtn = FAILED;

			break;

		}

	} else {

		/*

		 * FIXME(eric) - we are not tracking whether we could

		 * abort a timed out command or not.  not sure how

		 * we should treat them differently anyways.

		 */

		if (shost->hostt->eh_abort_handler)

			shost->hostt->eh_abort_handler(scmd);

		rtn = FAILED;

	}



	return rtn;

drivers/scsi/scsi_priv.h

+0 −1
Original line number Diff line number Diff line
@@ -22,7 +22,6 @@ struct Scsi_Host; 
 * Scsi Error Handler Flags

 */

#define SCSI_EH_CANCEL_CMD	0x0001	/* Cancel this cmd */

#define SCSI_EH_REC_TIMEOUT	0x0002	/* EH retry timed out */



#define SCSI_SENSE_VALID(scmd) \

	(((scmd)->sense_buffer[0] & 0x70) == 0x70)

include/scsi/scsi_host.h

+3 −2
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include <linux/workqueue.h>



struct block_device;

struct completion;

struct module;

struct scsi_cmnd;

struct scsi_device;
@@ -467,7 +468,7 @@ struct Scsi_Host { 


	struct list_head	eh_cmd_q;

	struct task_struct    * ehandler;  /* Error recovery thread. */

	struct semaphore      * eh_action; /* Wait for specific actions on the

	struct completion     * eh_action; /* Wait for specific actions on the

					      host. */

	wait_queue_head_t       host_wait;

	struct scsi_host_template *hostt;