[SCSI] consolidate command allocation in a single place

Since the way we allocate commands with a separate sense buffer is
getting complicated, we should isolate setup and teardown to a single
routine so that if it gets even more complex, there's only one place
in the code that needs to be altered.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 50 insertions, 32 deletions

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index c78b836f59dd..2cf9a625f227 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -166,6 +166,51 @@ static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
 static DEFINE_MUTEX(host_cmd_pool_mutex);
 
 /**
+ * scsi_pool_alloc_command - internal function to get a fully allocated command
+ * @pool:       slab pool to allocate the command from
+ * @gfp_mask:   mask for the allocation
+ *
+ * Returns a fully allocated command (with the allied sense buffer) or
+ * NULL on failure
+ */
+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_alloc(pool->cmd_slab, gfp_mask | pool->gfp_mask);
+        if (!cmd)
+                return NULL;
+
+        memset(cmd, 0, sizeof(*cmd));
+
+        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;
+}
+
+/**
+ * scsi_pool_free_command - internal function to release a command
+ * @pool:       slab pool to allocate the command from
+ * @cmd:        command to release
+ *
+ * the command must previously have been allocated by
+ * scsi_pool_alloc_command.
+ */
+static void
+scsi_pool_free_command(struct scsi_host_cmd_pool *pool,
+                         struct scsi_cmnd *cmd)
+{
+        kmem_cache_free(pool->sense_slab, cmd->sense_buffer);
+        kmem_cache_free(pool->cmd_slab, cmd);
+}
+
+/**
  * __scsi_get_command - Allocate a struct scsi_cmnd
  * @shost: host to transmit command
  * @gfp_mask: allocation mask
@@ -178,20 +223,7 @@ 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->cmd_slab,
-                               gfp_mask | shost->cmd_pool->gfp_mask);
-
-        if (likely(cmd)) {
-                buf = kmem_cache_alloc(shost->cmd_pool->sense_slab,
-                                       gfp_mask | shost->cmd_pool->gfp_mask);
-                if (likely(buf)) {
-                        memset(cmd, 0, sizeof(*cmd));
-                        cmd->sense_buffer = buf;
-                } else {
-                        kmem_cache_free(shost->cmd_pool->cmd_slab, cmd);
-                        cmd = NULL;
-                }
-        }
+        cmd = scsi_pool_alloc_command(shost->cmd_pool, gfp_mask);
 
         if (unlikely(!cmd)) {
                 unsigned long flags;
@@ -268,11 +300,8 @@ void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
         }
         spin_unlock_irqrestore(&shost->free_list_lock, flags);
 
-        if (likely(cmd != NULL)) {
-                kmem_cache_free(shost->cmd_pool->sense_slab,
-                                cmd->sense_buffer);
-                kmem_cache_free(shost->cmd_pool->cmd_slab, cmd);
-        }
+        if (likely(cmd != NULL))
+                scsi_pool_free_command(shost->cmd_pool, cmd);
 
         put_device(dev);
 }
@@ -348,23 +377,14 @@ int scsi_setup_command_freelist(struct Scsi_Host *shost)
         /*
          * Get one backup command for this host.
          */
-        cmd = kmem_cache_alloc(shost->cmd_pool->cmd_slab,
-                               GFP_KERNEL | shost->cmd_pool->gfp_mask);
+        cmd = scsi_pool_alloc_command(shost->cmd_pool, GFP_KERNEL);
         if (!cmd)
                 goto fail2;
 
-        cmd->sense_buffer = kmem_cache_alloc(shost->cmd_pool->sense_slab,
-                                             GFP_KERNEL |
-                                             shost->cmd_pool->gfp_mask);
-        if (!cmd->sense_buffer)
-                goto fail2;
-
         list_add(&cmd->list, &shost->free_list);
         return 0;
 
  fail2:
-        if (cmd)
-                kmem_cache_free(shost->cmd_pool->cmd_slab, cmd);
         mutex_lock(&host_cmd_pool_mutex);
         if (!--pool->users) {
                 kmem_cache_destroy(pool->cmd_slab);
@@ -386,9 +406,7 @@ 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(shost->cmd_pool->sense_slab,
-                                cmd->sense_buffer);
-                kmem_cache_free(shost->cmd_pool->cmd_slab, cmd);
+                scsi_pool_free_command(shost->cmd_pool, cmd);
         }
 
         mutex_lock(&host_cmd_pool_mutex);