[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>

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index c78b836..2cf9a62 100644 (file)
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -165,6 +165,51 @@ 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
@@ -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);