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Date: Mon, 25 May 2009 09:30:48 +0200
From: Jens Axboe <jens.axboe@...cle.com>
To: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc: chris.mason@...cle.com, david@...morbit.com, hch@...radead.org,
akpm@...ux-foundation.org, jack@...e.cz,
yanmin_zhang@...ux.intel.com, Jens Axboe <jens.axboe@...cle.com>
Subject: [PATCH 03/13] scsi: unify allocation of scsi command and sense buffer
Fold the sense buffer into the command, thereby eliminating a slab
allocation and free per command.
Signed-off-by: Jens Axboe <jens.axboe@...cle.com>
---
drivers/scsi/scsi.c | 44 ++++++++++----------------------------------
include/scsi/scsi_cmnd.h | 12 ++++++------
2 files changed, 16 insertions(+), 40 deletions(-)
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 166417a..6a993af 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -133,7 +133,6 @@ EXPORT_SYMBOL(scsi_device_type);
struct scsi_host_cmd_pool {
struct kmem_cache *cmd_slab;
- struct kmem_cache *sense_slab;
unsigned int users;
char *cmd_name;
char *sense_name;
@@ -167,20 +166,9 @@ static DEFINE_MUTEX(host_cmd_pool_mutex);
static struct scsi_cmnd *
scsi_pool_alloc_command(struct scsi_host_cmd_pool *pool, gfp_t gfp_mask)
{
- struct scsi_cmnd *cmd;
-
- cmd = kmem_cache_zalloc(pool->cmd_slab, gfp_mask | pool->gfp_mask);
- if (!cmd)
- return NULL;
+ gfp_t gfp = gfp_mask | pool->gfp_mask;
- cmd->sense_buffer = kmem_cache_alloc(pool->sense_slab,
- gfp_mask | pool->gfp_mask);
- if (!cmd->sense_buffer) {
- kmem_cache_free(pool->cmd_slab, cmd);
- return NULL;
- }
-
- return cmd;
+ return kmem_cache_zalloc(pool->cmd_slab, gfp);
}
/**
@@ -198,7 +186,6 @@ scsi_pool_free_command(struct scsi_host_cmd_pool *pool,
if (cmd->prot_sdb)
kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
- kmem_cache_free(pool->sense_slab, cmd->sense_buffer);
kmem_cache_free(pool->cmd_slab, cmd);
}
@@ -242,7 +229,6 @@ scsi_host_alloc_command(struct Scsi_Host *shost, gfp_t gfp_mask)
struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
{
struct scsi_cmnd *cmd;
- unsigned char *buf;
cmd = scsi_host_alloc_command(shost, gfp_mask);
@@ -257,11 +243,8 @@ struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
}
spin_unlock_irqrestore(&shost->free_list_lock, flags);
- if (cmd) {
- buf = cmd->sense_buffer;
+ if (cmd)
memset(cmd, 0, sizeof(*cmd));
- cmd->sense_buffer = buf;
- }
}
return cmd;
@@ -361,19 +344,13 @@ static struct scsi_host_cmd_pool *scsi_get_host_cmd_pool(gfp_t gfp_mask)
pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :
&scsi_cmd_pool;
if (!pool->users) {
- pool->cmd_slab = kmem_cache_create(pool->cmd_name,
- sizeof(struct scsi_cmnd), 0,
- pool->slab_flags, NULL);
- if (!pool->cmd_slab)
- goto fail;
+ unsigned int slab_size;
- pool->sense_slab = kmem_cache_create(pool->sense_name,
- SCSI_SENSE_BUFFERSIZE, 0,
- pool->slab_flags, NULL);
- if (!pool->sense_slab) {
- kmem_cache_destroy(pool->cmd_slab);
+ slab_size = sizeof(struct scsi_cmnd) + SCSI_SENSE_BUFFERSIZE;
+ pool->cmd_slab = kmem_cache_create(pool->cmd_name, slab_size,
+ 0, pool->slab_flags, NULL);
+ if (!pool->cmd_slab)
goto fail;
- }
}
pool->users++;
@@ -397,10 +374,9 @@ static void scsi_put_host_cmd_pool(gfp_t gfp_mask)
*/
BUG_ON(pool->users == 0);
- if (!--pool->users) {
+ if (!--pool->users)
kmem_cache_destroy(pool->cmd_slab);
- kmem_cache_destroy(pool->sense_slab);
- }
+
mutex_unlock(&host_cmd_pool_mutex);
}
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 43b50d3..649ad36 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -102,12 +102,6 @@ struct scsi_cmnd {
struct request *request; /* The command we are
working on */
-#define SCSI_SENSE_BUFFERSIZE 96
- unsigned char *sense_buffer;
- /* obtained by REQUEST SENSE when
- * CHECK CONDITION is received on original
- * command (auto-sense) */
-
/* Low-level done function - can be used by low-level driver to point
* to completion function. Not used by mid/upper level code. */
void (*scsi_done) (struct scsi_cmnd *);
@@ -129,6 +123,12 @@ struct scsi_cmnd {
int result; /* Status code from lower level driver */
unsigned char tag; /* SCSI-II queued command tag */
+
+#define SCSI_SENSE_BUFFERSIZE 96
+ unsigned char sense_buffer[0];
+ /* obtained by REQUEST SENSE when
+ * CHECK CONDITION is received on original
+ * command (auto-sense) */
};
extern struct scsi_cmnd *scsi_get_command(struct scsi_device *, gfp_t);
--
1.6.3.rc0.1.gf800
--
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