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Commit 74665016 authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

scsi: convert host_busy to atomic_t 



Avoid taking the host-wide host_lock to check the per-host queue limit.
Instead we do an atomic_inc_return early on to grab our slot in the queue,
and if necessary decrement it after finishing all checks.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarWebb Scales <webbnh@hp.com>
Acked-by: default avatarJens Axboe <axboe@kernel.dk>
Tested-by: default avatarBart Van Assche <bvanassche@acm.org>
Tested-by: default avatarRobert Elliott <elliott@hp.com>
parent 7ae65c0f

drivers/scsi/advansys.c

+2 −2
Original line number Diff line number Diff line
@@ -2512,7 +2512,7 @@ static void asc_prt_scsi_host(struct Scsi_Host *s) 


	printk("Scsi_Host at addr 0x%p, device %s\n", s, dev_name(boardp->dev));

	printk(" host_busy %u, host_no %d,\n",

	       s->host_busy, s->host_no);

	       atomic_read(&s->host_busy), s->host_no);



	printk(" base 0x%lx, io_port 0x%lx, irq %d,\n",

	       (ulong)s->base, (ulong)s->io_port, boardp->irq);
@@ -3346,7 +3346,7 @@ static void asc_prt_driver_conf(struct seq_file *m, struct Scsi_Host *shost) 


	seq_printf(m,

		   " host_busy %u, max_id %u, max_lun %llu, max_channel %u\n",

		   shost->host_busy, shost->max_id,

		   atomic_read(&shost->host_busy), shost->max_id,

		   shost->max_lun, shost->max_channel);



	seq_printf(m,

drivers/scsi/libiscsi.c

+2 −2
Original line number Diff line number Diff line
@@ -2971,7 +2971,7 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn) 
	 */

	for (;;) {

		spin_lock_irqsave(session->host->host_lock, flags);

		if (!session->host->host_busy) { /* OK for ERL == 0 */

		if (!atomic_read(&session->host->host_busy)) { /* OK for ERL == 0 */

			spin_unlock_irqrestore(session->host->host_lock, flags);

			break;

		}
@@ -2979,7 +2979,7 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn) 
		msleep_interruptible(500);

		iscsi_conn_printk(KERN_INFO, conn, "iscsi conn_destroy(): "

				  "host_busy %d host_failed %d\n",

				  session->host->host_busy,

				  atomic_read(&session->host->host_busy),

				  session->host->host_failed);

		/*

		 * force eh_abort() to unblock

drivers/scsi/libsas/sas_scsi_host.c

+3 −2
Original line number Diff line number Diff line
@@ -813,7 +813,7 @@ void sas_scsi_recover_host(struct Scsi_Host *shost) 
	spin_unlock_irq(shost->host_lock);



	SAS_DPRINTK("Enter %s busy: %d failed: %d\n",

		    __func__, shost->host_busy, shost->host_failed);

		    __func__, atomic_read(&shost->host_busy), shost->host_failed);

	/*

	 * Deal with commands that still have SAS tasks (i.e. they didn't

	 * complete via the normal sas_task completion mechanism),
@@ -858,7 +858,8 @@ void sas_scsi_recover_host(struct Scsi_Host *shost) 
		goto retry;



	SAS_DPRINTK("--- Exit %s: busy: %d failed: %d tries: %d\n",

		    __func__, shost->host_busy, shost->host_failed, tries);

		    __func__, atomic_read(&shost->host_busy),

		    shost->host_failed, tries);

}



enum blk_eh_timer_return sas_scsi_timed_out(struct scsi_cmnd *cmd)

drivers/scsi/qlogicpti.c

+1 −1
Original line number Diff line number Diff line
@@ -959,7 +959,7 @@ static inline void update_can_queue(struct Scsi_Host *host, u_int in_ptr, u_int 
	/* Temporary workaround until bug is found and fixed (one bug has been found

	   already, but fixing it makes things even worse) -jj */

	int num_free = QLOGICPTI_REQ_QUEUE_LEN - REQ_QUEUE_DEPTH(in_ptr, out_ptr) - 64;

	host->can_queue = host->host_busy + num_free;

	host->can_queue = atomic_read(&host->host_busy) + num_free;

	host->sg_tablesize = QLOGICPTI_MAX_SG(num_free);

}

drivers/scsi/scsi.c

+1 −1
Original line number Diff line number Diff line
@@ -600,7 +600,7 @@ void scsi_log_completion(struct scsi_cmnd *cmd, int disposition) 
			if (level > 3)

				scmd_printk(KERN_INFO, cmd,

					    "scsi host busy %d failed %d\n",

					    cmd->device->host->host_busy,

					    atomic_read(&cmd->device->host->host_busy),

					    cmd->device->host->host_failed);

		}

	}