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Commit de25deb1 authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by James Bottomley
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[SCSI] use dynamically allocated sense buffer 

This removes static array sense_buffer in scsi_cmnd and uses
dynamically allocated sense_buffer (with GFP_DMA).

The reason for doing this is that some architectures need cacheline
aligned buffer for DMA:

http://lkml.org/lkml/2007/11/19/2



The problems are that scsi_eh_prep_cmnd puts scsi_cmnd::sense_buffer
to sglist and some LLDs directly DMA to scsi_cmnd::sense_buffer. It's
necessary to DMA to scsi_cmnd::sense_buffer safely. This patch solves
these issues.

__scsi_get_command allocates sense_buffer via kmem_cache_alloc and
attaches it to a scsi_cmnd so everything just work as before.

Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent b30c2fc1

drivers/scsi/hosts.c

+8 −1
Original line number Diff line number Diff line
@@ -268,6 +268,7 @@ static void scsi_host_dev_release(struct device *dev) 
	}



	scsi_destroy_command_freelist(shost);

	scsi_destroy_command_sense_buffer(shost);

	if (shost->bqt)

		blk_free_tags(shost->bqt);
@@ -372,10 +373,14 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) 
	else

		shost->dma_boundary = 0xffffffff;



	rval = scsi_setup_command_freelist(shost);

	rval = scsi_setup_command_sense_buffer(shost);

	if (rval)

		goto fail_kfree;



	rval = scsi_setup_command_freelist(shost);

	if (rval)

		goto fail_destroy_sense;



	device_initialize(&shost->shost_gendev);

	snprintf(shost->shost_gendev.bus_id, BUS_ID_SIZE, "host%d",

		shost->host_no);
@@ -399,6 +404,8 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) 


 fail_destroy_freelist:

	scsi_destroy_command_freelist(shost);

 fail_destroy_sense:

	scsi_destroy_command_sense_buffer(shost);

 fail_kfree:

	kfree(shost);

	return NULL;

drivers/scsi/scsi.c

+59 −2
Original line number Diff line number Diff line
@@ -161,6 +161,9 @@ static struct scsi_host_cmd_pool scsi_cmd_dma_pool = { 


static DEFINE_MUTEX(host_cmd_pool_mutex);



static struct kmem_cache *sense_buffer_slab;

static int sense_buffer_slab_users;



/**

 * __scsi_get_command - Allocate a struct scsi_cmnd

 * @shost: host to transmit command
@@ -172,6 +175,7 @@ static DEFINE_MUTEX(host_cmd_pool_mutex); 
struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)

{

	struct scsi_cmnd *cmd;

	unsigned char *buf;



	cmd = kmem_cache_alloc(shost->cmd_pool->slab,

			gfp_mask | shost->cmd_pool->gfp_mask);
@@ -186,6 +190,21 @@ struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask) 
			list_del_init(&cmd->list);

		}

		spin_unlock_irqrestore(&shost->free_list_lock, flags);



		if (cmd) {

			buf = cmd->sense_buffer;

			memset(cmd, 0, sizeof(*cmd));

			cmd->sense_buffer = buf;

		}

	} else {

		buf = kmem_cache_alloc(sense_buffer_slab, __GFP_DMA|gfp_mask);

		if (likely(buf)) {

			memset(cmd, 0, sizeof(*cmd));

			cmd->sense_buffer = buf;

		} else {

			kmem_cache_free(shost->cmd_pool->slab, cmd);

			cmd = NULL;

		}

	}



	return cmd;
@@ -212,7 +231,6 @@ struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask) 
	if (likely(cmd != NULL)) {

		unsigned long flags;



		memset(cmd, 0, sizeof(*cmd));

		cmd->device = dev;

		init_timer(&cmd->eh_timeout);

		INIT_LIST_HEAD(&cmd->list);
@@ -246,8 +264,10 @@ void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd, 
	}

	spin_unlock_irqrestore(&shost->free_list_lock, flags);



	if (likely(cmd != NULL))

	if (likely(cmd != NULL)) {

		kmem_cache_free(sense_buffer_slab, cmd->sense_buffer);

		kmem_cache_free(shost->cmd_pool->slab, cmd);

	}



	put_device(dev);

}
@@ -290,6 +310,7 @@ int scsi_setup_command_freelist(struct Scsi_Host *shost) 
{

	struct scsi_host_cmd_pool *pool;

	struct scsi_cmnd *cmd;

	unsigned char *sense_buffer;



	spin_lock_init(&shost->free_list_lock);

	INIT_LIST_HEAD(&shost->free_list);
@@ -319,9 +340,18 @@ int scsi_setup_command_freelist(struct Scsi_Host *shost) 
			GFP_KERNEL | shost->cmd_pool->gfp_mask);

	if (!cmd)

		goto fail2;



	sense_buffer = kmem_cache_alloc(sense_buffer_slab,

					GFP_KERNEL | __GFP_DMA);

	if (!sense_buffer)

		goto destroy_backup;



	cmd->sense_buffer = sense_buffer;

	list_add(&cmd->list, &shost->free_list);

	return 0;



destroy_backup:

	kmem_cache_free(shost->cmd_pool->slab, cmd);

 fail2:

	mutex_lock(&host_cmd_pool_mutex);

	if (!--pool->users)
@@ -342,6 +372,7 @@ void scsi_destroy_command_freelist(struct Scsi_Host *shost) 


		cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);

		list_del_init(&cmd->list);

		kmem_cache_free(sense_buffer_slab, cmd->sense_buffer);

		kmem_cache_free(shost->cmd_pool->slab, cmd);

	}
@@ -351,6 +382,32 @@ void scsi_destroy_command_freelist(struct Scsi_Host *shost) 
	mutex_unlock(&host_cmd_pool_mutex);

}



int scsi_setup_command_sense_buffer(struct Scsi_Host *shost)

{

	mutex_lock(&host_cmd_pool_mutex);

	if (!sense_buffer_slab_users) {

		sense_buffer_slab = kmem_cache_create("scsi_sense_buffer",

						      SCSI_SENSE_BUFFERSIZE,

						      0, SLAB_CACHE_DMA, NULL);

		if (!sense_buffer_slab) {

			mutex_unlock(&host_cmd_pool_mutex);

			return -ENOMEM;

		}

	}

	sense_buffer_slab_users++;

	mutex_unlock(&host_cmd_pool_mutex);



	return 0;

}



void scsi_destroy_command_sense_buffer(struct Scsi_Host *shost)

{

	mutex_lock(&host_cmd_pool_mutex);

	if (!--sense_buffer_slab_users)

		kmem_cache_destroy(sense_buffer_slab);

	mutex_unlock(&host_cmd_pool_mutex);

}



#ifdef CONFIG_SCSI_LOGGING

void scsi_log_send(struct scsi_cmnd *cmd)

{

drivers/scsi/scsi_priv.h

+2 −0
Original line number Diff line number Diff line
@@ -27,6 +27,8 @@ extern void scsi_exit_hosts(void); 
extern int scsi_dispatch_cmd(struct scsi_cmnd *cmd);

extern int scsi_setup_command_freelist(struct Scsi_Host *shost);

extern void scsi_destroy_command_freelist(struct Scsi_Host *shost);

extern int scsi_setup_command_sense_buffer(struct Scsi_Host *shost);

extern void scsi_destroy_command_sense_buffer(struct Scsi_Host *shost);

extern void __scsi_done(struct scsi_cmnd *cmd);

#ifdef CONFIG_SCSI_LOGGING

void scsi_log_send(struct scsi_cmnd *cmd);

include/scsi/scsi_cmnd.h

+1 −1
Original line number Diff line number Diff line
@@ -88,7 +88,7 @@ struct scsi_cmnd { 
				   	   working on */



#define SCSI_SENSE_BUFFERSIZE 	96

	unsigned char sense_buffer[SCSI_SENSE_BUFFERSIZE];

	unsigned char *sense_buffer;

				/* obtained by REQUEST SENSE when

				 * CHECK CONDITION is received on original

				 * command (auto-sense) */