[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: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 54ff611..0a4a5b8 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -161,6 +161,9 @@
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 @@
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 @@
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 @@
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 @@
}
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 @@
{
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 @@
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 @@
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 @@
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)
{