Commit 1aea6434 authored by Jens Axboe's avatar Jens Axboe
Browse files

[SCSI] Kill the SCSI softirq handling 



This patch moves the SCSI softirq handling to the block layer version.
There should be no functional changes.

Signed-off-by: default avatarJens Axboe <axboe@suse.de>
parent ff856bad

drivers/scsi/scsi.c

+8 −101
Original line number Diff line number Diff line
@@ -69,7 +69,6 @@ 
#include "scsi_logging.h"



static void scsi_done(struct scsi_cmnd *cmd);

static int scsi_retry_command(struct scsi_cmnd *cmd);



/*

 * Definitions and constants.
@@ -752,7 +751,7 @@ static void scsi_done(struct scsi_cmnd *cmd) 
 * isn't running --- used by scsi_times_out */

void __scsi_done(struct scsi_cmnd *cmd)

{

	unsigned long flags;

	struct request *rq = cmd->request;



	/*

	 * Set the serial numbers back to zero
@@ -763,71 +762,14 @@ void __scsi_done(struct scsi_cmnd *cmd) 
	if (cmd->result)

		atomic_inc(&cmd->device->ioerr_cnt);



	/*

	 * Next, enqueue the command into the done queue.

	 * It is a per-CPU queue, so we just disable local interrupts

	 * and need no spinlock.

	 */

	local_irq_save(flags);

	list_add_tail(&cmd->eh_entry, &__get_cpu_var(scsi_done_q));

	raise_softirq_irqoff(SCSI_SOFTIRQ);

	local_irq_restore(flags);

}

	BUG_ON(!rq);



/**

 * scsi_softirq - Perform post-interrupt processing of finished SCSI commands.

 *

 * This is the consumer of the done queue.

 *

 * This is called with all interrupts enabled.  This should reduce

 * interrupt latency, stack depth, and reentrancy of the low-level

 * drivers.

	/*

	 * The uptodate/nbytes values don't matter, as we allow partial

	 * completes and thus will check this in the softirq callback

	 */

static void scsi_softirq(struct softirq_action *h)

{

	int disposition;

	LIST_HEAD(local_q);



	local_irq_disable();

	list_splice_init(&__get_cpu_var(scsi_done_q), &local_q);

	local_irq_enable();



	while (!list_empty(&local_q)) {

		struct scsi_cmnd *cmd = list_entry(local_q.next,

						   struct scsi_cmnd, eh_entry);

		/* The longest time any command should be outstanding is the

		 * per command timeout multiplied by the number of retries.

		 *

		 * For a typical command, this is 2.5 minutes */

		unsigned long wait_for 

			= cmd->allowed * cmd->timeout_per_command;

		list_del_init(&cmd->eh_entry);



		disposition = scsi_decide_disposition(cmd);

		if (disposition != SUCCESS &&

		    time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {

			sdev_printk(KERN_ERR, cmd->device,

				    "timing out command, waited %lus\n",

				    wait_for/HZ);

			disposition = SUCCESS;

		}

			

		scsi_log_completion(cmd, disposition);

		switch (disposition) {

		case SUCCESS:

			scsi_finish_command(cmd);

			break;

		case NEEDS_RETRY:

			scsi_retry_command(cmd);

			break;

		case ADD_TO_MLQUEUE:

			scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);

			break;

		default:

			if (!scsi_eh_scmd_add(cmd, 0))

				scsi_finish_command(cmd);

		}

	}

	rq->completion_data = cmd;

	blk_complete_request(rq);

}



/*
@@ -840,7 +782,7 @@ static void scsi_softirq(struct softirq_action *h) 
 *              level drivers should not become re-entrant as a result of

 *              this.

 */

static int scsi_retry_command(struct scsi_cmnd *cmd)

int scsi_retry_command(struct scsi_cmnd *cmd)

{

	/*

	 * Restore the SCSI command state.
@@ -1273,38 +1215,6 @@ int scsi_device_cancel(struct scsi_device *sdev, int recovery) 
}

EXPORT_SYMBOL(scsi_device_cancel);



#ifdef CONFIG_HOTPLUG_CPU

static int scsi_cpu_notify(struct notifier_block *self,

			   unsigned long action, void *hcpu)

{

	int cpu = (unsigned long)hcpu;



	switch(action) {

	case CPU_DEAD:

		/* Drain scsi_done_q. */

		local_irq_disable();

		list_splice_init(&per_cpu(scsi_done_q, cpu),

				 &__get_cpu_var(scsi_done_q));

		raise_softirq_irqoff(SCSI_SOFTIRQ);

		local_irq_enable();

		break;

	default:

		break;

	}

	return NOTIFY_OK;

}



static struct notifier_block __devinitdata scsi_cpu_nb = {

	.notifier_call	= scsi_cpu_notify,

};



#define register_scsi_cpu() register_cpu_notifier(&scsi_cpu_nb)

#define unregister_scsi_cpu() unregister_cpu_notifier(&scsi_cpu_nb)

#else

#define register_scsi_cpu()

#define unregister_scsi_cpu()

#endif /* CONFIG_HOTPLUG_CPU */



MODULE_DESCRIPTION("SCSI core");

MODULE_LICENSE("GPL");
@@ -1338,8 +1248,6 @@ static int __init init_scsi(void) 
		INIT_LIST_HEAD(&per_cpu(scsi_done_q, i));



	devfs_mk_dir("scsi");

	open_softirq(SCSI_SOFTIRQ, scsi_softirq, NULL);

	register_scsi_cpu();

	printk(KERN_NOTICE "SCSI subsystem initialized\n");

	return 0;
@@ -1367,7 +1275,6 @@ static void __exit exit_scsi(void) 
	devfs_remove("scsi");

	scsi_exit_procfs();

	scsi_exit_queue();

	unregister_scsi_cpu();

}



subsys_initcall(init_scsi);

drivers/scsi/scsi_lib.c

+36 −0
Original line number Diff line number Diff line
@@ -1493,6 +1493,41 @@ static void scsi_kill_request(struct request *req, request_queue_t *q) 
	__scsi_done(cmd);

}



static void scsi_softirq_done(struct request *rq)

{

	struct scsi_cmnd *cmd = rq->completion_data;

	unsigned long wait_for = cmd->allowed * cmd->timeout_per_command;

	int disposition;



	INIT_LIST_HEAD(&cmd->eh_entry);



	disposition = scsi_decide_disposition(cmd);

	if (disposition != SUCCESS &&

	    time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {

		sdev_printk(KERN_ERR, cmd->device,

			    "timing out command, waited %lus\n",

			    wait_for/HZ);

		disposition = SUCCESS;

	}

			

	scsi_log_completion(cmd, disposition);



	switch (disposition) {

		case SUCCESS:

			scsi_finish_command(cmd);

			break;

		case NEEDS_RETRY:

			scsi_retry_command(cmd);

			break;

		case ADD_TO_MLQUEUE:

			scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);

			break;

		default:

			if (!scsi_eh_scmd_add(cmd, 0))

				scsi_finish_command(cmd);

	}

}



/*

 * Function:    scsi_request_fn()

 *
@@ -1667,6 +1702,7 @@ struct request_queue *scsi_alloc_queue(struct scsi_device *sdev) 
	blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));

	blk_queue_segment_boundary(q, shost->dma_boundary);

	blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);

	blk_queue_softirq_done(q, scsi_softirq_done);



	if (!shost->use_clustering)

		clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);

drivers/scsi/scsi_priv.h

+1 −0
Original line number Diff line number Diff line
@@ -44,6 +44,7 @@ extern void scsi_init_cmd_from_req(struct scsi_cmnd *cmd, 
		struct scsi_request *sreq);

extern void __scsi_release_request(struct scsi_request *sreq);

extern void __scsi_done(struct scsi_cmnd *cmd);

extern int scsi_retry_command(struct scsi_cmnd *cmd);

#ifdef CONFIG_SCSI_LOGGING

void scsi_log_send(struct scsi_cmnd *cmd);

void scsi_log_completion(struct scsi_cmnd *cmd, int disposition);

include/linux/interrupt.h

+0 −1
Original line number Diff line number Diff line
@@ -113,7 +113,6 @@ enum 
	NET_TX_SOFTIRQ,

	NET_RX_SOFTIRQ,

	BLOCK_SOFTIRQ,

	SCSI_SOFTIRQ,

	TASKLET_SOFTIRQ

};