scsi_error.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,846 行 · 第 1/4 页

/*
 *  scsi_error.c Copyright (C) 1997 Eric Youngdale
 *
 *  SCSI error/timeout handling
 *      Initial versions: Eric Youngdale.  Based upon conversations with
 *                        Leonard Zubkoff and David Miller at Linux Expo, 
 *                        ideas originating from all over the place.
 *
 *	Restructured scsi_unjam_host and associated functions.
 *	September 04, 2002 Mike Anderson ([e-mail])
 *
 *	Forward port of Russell King's ([e-mail]) changes and
 *	minor  cleanups.
 *	September 30, 2002 Mike Anderson ([e-mail])
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/blkdev.h>
#include <linux/delay.h>

#include <scsi/scsi.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/scsi_request.h>

#include "scsi_priv.h"
#include "scsi_logging.h"

#define SENSE_TIMEOUT		(10*HZ)
#define START_UNIT_TIMEOUT	(30*HZ)

/*
 * These should *probably* be handled by the host itself.
 * Since it is allowed to sleep, it probably should.
 */
#define BUS_RESET_SETTLE_TIME   (10)
#define HOST_RESET_SETTLE_TIME  (10)

/* called with shost->host_lock held */
void scsi_eh_wakeup(struct Scsi_Host *shost)
{
	if (shost->host_busy == shost->host_failed) {
		up(shost->eh_wait);
		SCSI_LOG_ERROR_RECOVERY(5,
				printk("Waking error handler thread\n"));
	}
}

/**
 * scsi_eh_scmd_add - add scsi cmd to error handling.
 * @scmd:	scmd to run eh on.
 * @eh_flag:	optional SCSI_EH flag.
 *
 * Return value:
 *	0 on failure.
 **/
int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
{
	struct Scsi_Host *shost = scmd->device->host;
	unsigned long flags;

	if (shost->eh_wait == NULL)
		return 0;

	spin_lock_irqsave(shost->host_lock, flags);

	scsi_eh_eflags_set(scmd, eh_flag);
	/*
	 * FIXME: Can we stop setting owner and state.
	 */
	scmd->owner = SCSI_OWNER_ERROR_HANDLER;
	scmd->state = SCSI_STATE_FAILED;
	/*
	 * Set the serial_number_at_timeout to the current
	 * serial_number
	 */
	scmd->serial_number_at_timeout = scmd->serial_number;
	list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
	set_bit(SHOST_RECOVERY, &shost->shost_state);
	shost->host_failed++;
	scsi_eh_wakeup(shost);
	spin_unlock_irqrestore(shost->host_lock, flags);
	return 1;
}

/**
 * scsi_add_timer - Start timeout timer for a single scsi command.
 * @scmd:	scsi command that is about to start running.
 * @timeout:	amount of time to allow this command to run.
 * @complete:	timeout function to call if timer isn't canceled.
 *
 * Notes:
 *    This should be turned into an inline function.  Each scsi command
 *    has its own timer, and as it is added to the queue, we set up the
 *    timer.  When the command completes, we cancel the timer.
 **/
void scsi_add_timer(struct scsi_cmnd *scmd, int timeout,
		    void (*complete)(struct scsi_cmnd *))
{

	/*
	 * If the clock was already running for this command, then
	 * first delete the timer.  The timer handling code gets rather
	 * confused if we don't do this.
	 */
	if (scmd->eh_timeout.function)
		del_timer(&scmd->eh_timeout);

	scmd->eh_timeout.data = (unsigned long)scmd;
	scmd->eh_timeout.expires = jiffies + timeout;
	scmd->eh_timeout.function = (void (*)(unsigned long)) complete;

	SCSI_LOG_ERROR_RECOVERY(5, printk("%s: scmd: %p, time:"
					  " %d, (%p)\n", __FUNCTION__,
					  scmd, timeout, complete));

	add_timer(&scmd->eh_timeout);
}

/**
 * scsi_delete_timer - Delete/cancel timer for a given function.
 * @scmd:	Cmd that we are canceling timer for
 *
 * Notes:
 *     This should be turned into an inline function.
 *
 * Return value:
 *     1 if we were able to detach the timer.  0 if we blew it, and the
 *     timer function has already started to run.
 **/
int scsi_delete_timer(struct scsi_cmnd *scmd)
{
	int rtn;

	rtn = del_timer(&scmd->eh_timeout);

	SCSI_LOG_ERROR_RECOVERY(5, printk("%s: scmd: %p,"
					 " rtn: %d\n", __FUNCTION__,
					 scmd, rtn));

	scmd->eh_timeout.data = (unsigned long)NULL;
	scmd->eh_timeout.function = NULL;

	return rtn;
}

/**
 * scsi_times_out - Timeout function for normal scsi commands.
 * @scmd:	Cmd that is timing out.
 *
 * Notes:
 *     We do not need to lock this.  There is the potential for a race
 *     only in that the normal completion handling might run, but if the
 *     normal completion function determines that the timer has already
 *     fired, then it mustn't do anything.
 **/
void scsi_times_out(struct scsi_cmnd *scmd)
{
	scsi_log_completion(scmd, TIMEOUT_ERROR);

	if (scmd->device->host->hostt->eh_timed_out)
		switch (scmd->device->host->hostt->eh_timed_out(scmd)) {
		case EH_HANDLED:
			__scsi_done(scmd);
			return;
		case EH_RESET_TIMER:
			/* This allows a single retry even of a command
			 * with allowed == 0 */
			if (scmd->retries++ > scmd->allowed)
				break;
			scsi_add_timer(scmd, scmd->timeout_per_command,
				       scsi_times_out);
			return;
		case EH_NOT_HANDLED:
			break;
		}

	if (unlikely(!scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD))) {
		panic("Error handler thread not present at %p %p %s %d",
		      scmd, scmd->device->host, __FILE__, __LINE__);
	}
}

/**
 * scsi_block_when_processing_errors - Prevent cmds from being queued.
 * @sdev:	Device on which we are performing recovery.
 *
 * Description:
 *     We block until the host is out of error recovery, and then check to
 *     see whether the host or the device is offline.
 *
 * Return value:
 *     0 when dev was taken offline by error recovery. 1 OK to proceed.
 **/
int scsi_block_when_processing_errors(struct scsi_device *sdev)
{
	int online;

	wait_event(sdev->host->host_wait, (!test_bit(SHOST_RECOVERY, &sdev->host->shost_state)));

	online = scsi_device_online(sdev);

	SCSI_LOG_ERROR_RECOVERY(5, printk("%s: rtn: %d\n", __FUNCTION__,
					  online));

	return online;
}

#ifdef CONFIG_SCSI_LOGGING
/**
 * scsi_eh_prt_fail_stats - Log info on failures.
 * @shost:	scsi host being recovered.
 * @work_q:	Queue of scsi cmds to process.
 **/
static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
					  struct list_head *work_q)
{
	struct scsi_cmnd *scmd;
	struct scsi_device *sdev;
	int total_failures = 0;
	int cmd_failed = 0;
	int cmd_cancel = 0;
	int devices_failed = 0;

	shost_for_each_device(sdev, shost) {
		list_for_each_entry(scmd, work_q, eh_entry) {
			if (scmd->device == sdev) {
				++total_failures;
				if (scsi_eh_eflags_chk(scmd,
						       SCSI_EH_CANCEL_CMD))
					++cmd_cancel;
				else 
					++cmd_failed;
			}
		}

		if (cmd_cancel || cmd_failed) {
			SCSI_LOG_ERROR_RECOVERY(3,
				printk("%s: %d:%d:%d:%d cmds failed: %d,"
				       " cancel: %d\n",
				       __FUNCTION__, shost->host_no,
				       sdev->channel, sdev->id, sdev->lun,
				       cmd_failed, cmd_cancel));
			cmd_cancel = 0;
			cmd_failed = 0;
			++devices_failed;
		}
	}

	SCSI_LOG_ERROR_RECOVERY(2, printk("Total of %d commands on %d"
					  " devices require eh work\n",
				  total_failures, devices_failed));
}
#endif

/**
 * scsi_check_sense - Examine scsi cmd sense
 * @scmd:	Cmd to have sense checked.
 *
 * Return value:
 * 	SUCCESS or FAILED or NEEDS_RETRY
 **/
static int scsi_check_sense(struct scsi_cmnd *scmd)
{
	if (!SCSI_SENSE_VALID(scmd))
		return FAILED;

	if (scmd->sense_buffer[2] & 0xe0)
		return SUCCESS;

	switch (scmd->sense_buffer[2] & 0xf) {
	case NO_SENSE:
		return SUCCESS;
	case RECOVERED_ERROR:
		return /* soft_error */ SUCCESS;

	case ABORTED_COMMAND:
		return NEEDS_RETRY;
	case NOT_READY:
	case UNIT_ATTENTION:
		/*
		 * if we are expecting a cc/ua because of a bus reset that we
		 * performed, treat this just as a retry.  otherwise this is
		 * information that we should pass up to the upper-level driver
		 * so that we can deal with it there.
		 */
		if (scmd->device->expecting_cc_ua) {
			scmd->device->expecting_cc_ua = 0;
			return NEEDS_RETRY;
		}
		/*
		 * if the device is in the process of becoming ready, we 
		 * should retry.
		 */
		if ((scmd->sense_buffer[12] == 0x04) &&
			(scmd->sense_buffer[13] == 0x01)) {
			return NEEDS_RETRY;
		}
		/*
		 * if the device is not started, we need to wake
		 * the error handler to start the motor
		 */
		if (scmd->device->allow_restart &&
		    (scmd->sense_buffer[12] == 0x04) &&
		    (scmd->sense_buffer[13] == 0x02)) {
			return FAILED;
		}
		return SUCCESS;

		/* these three are not supported */
	case COPY_ABORTED:
	case VOLUME_OVERFLOW:
	case MISCOMPARE:
		return SUCCESS;

	case MEDIUM_ERROR:
		return NEEDS_RETRY;

	case ILLEGAL_REQUEST:
	case BLANK_CHECK:
	case DATA_PROTECT:
	case HARDWARE_ERROR:
	default:
		return SUCCESS;
	}
}

/**
 * scsi_eh_completed_normally - Disposition a eh cmd on return from LLD.
 * @scmd:	SCSI cmd to examine.
 *
 * Notes:
 *    This is *only* called when we are examining the status of commands
 *    queued during error recovery.  the main difference here is that we
 *    don't allow for the possibility of retries here, and we are a lot
 *    more restrictive about what we consider acceptable.
 **/
static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
{
	/*
	 * first check the host byte, to see if there is anything in there
	 * that would indicate what we need to do.
	 */
	if (host_byte(scmd->result) == DID_RESET) {
		/*
		 * rats.  we are already in the error handler, so we now
		 * get to try and figure out what to do next.  if the sense
		 * is valid, we have a pretty good idea of what to do.
		 * if not, we mark it as FAILED.
		 */
		return scsi_check_sense(scmd);
	}
	if (host_byte(scmd->result) != DID_OK)
		return FAILED;

	/*
	 * next, check the message byte.
	 */
	if (msg_byte(scmd->result) != COMMAND_COMPLETE)
		return FAILED;

	/*
	 * now, check the status byte to see if this indicates
	 * anything special.
	 */
	switch (status_byte(scmd->result)) {
	case GOOD:
	case COMMAND_TERMINATED:
		return SUCCESS;
	case CHECK_CONDITION:
		return scsi_check_sense(scmd);
	case CONDITION_GOOD:
	case INTERMEDIATE_GOOD:
	case INTERMEDIATE_C_GOOD:
		/*
		 * who knows?  FIXME(eric)
		 */
		return SUCCESS;
	case BUSY:
	case QUEUE_FULL:
	case RESERVATION_CONFLICT:
	default:
		return FAILED;
	}
	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)
{
	scsi_eh_eflags_set(scmd, SCSI_EH_REC_TIMEOUT);
	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd:%p\n", __FUNCTION__,
					  scmd));

	if (scmd->device->host->eh_action)
		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;
		scmd->owner = SCSI_OWNER_ERROR_HANDLER;

		SCSI_LOG_ERROR_RECOVERY(3, printk("%s scmd: %p result: %x\n",
					   __FUNCTION__, scmd, scmd->result));

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

/**
 * scsi_send_eh_cmnd  - send a cmd to a device as part of error recovery.
 * @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
 **/
static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, int timeout)
{
	struct Scsi_Host *host = scmd->device->host;
	DECLARE_MUTEX_LOCKED(sem);
	unsigned long flags;
	int rtn = SUCCESS;

	/*
	 * we will use a queued command if possible, otherwise we will
	 * emulate the queuing and calling of completion function ourselves.
	 */