[SCSI] target: Avoid mem leak and needless work in transport_generic_get_mem

In drivers/target/target_core_transport.c::transport_generic_get_mem()
there are a few potential memory leaks in the error paths. This patch
makes sure that we free previously allocated memory when other allocations
fail.  It also moves some work (INIT_LIST_HEAD() and assignment to
se_mem->se_len) below all the allocations so that if something fails we
don't do the work at all.
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Signed-off-by: NNicholas A. Bellinger <nab@linux-iscsi.org>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>

drivers/target/target_core_transport.c

@@ -4357,11 +4357,9 @@ transport_generic_get_mem(struct se_cmd *cmd, u32 length, u32 dma_size)
 			printk(KERN_ERR "Unable to allocate struct se_mem\n");
 			goto out;
 		}
-		INIT_LIST_HEAD(&se_mem->se_list);
-		se_mem->se_len = (length > dma_size) ? dma_size : length;
 
 /* #warning FIXME Allocate contigous pages for struct se_mem elements */
-		se_mem->se_page = (struct page *) alloc_pages(GFP_KERNEL, 0);
+		se_mem->se_page = alloc_pages(GFP_KERNEL, 0);
 		if (!(se_mem->se_page)) {
 			printk(KERN_ERR "alloc_pages() failed\n");
 			goto out;
@@ -4372,6 +4370,8 @@ transport_generic_get_mem(struct se_cmd *cmd, u32 length, u32 dma_size)
 			printk(KERN_ERR "kmap_atomic() failed\n");
 			goto out;
 		}
+		INIT_LIST_HEAD(&se_mem->se_list);
+		se_mem->se_len = (length > dma_size) ? dma_size : length;
 		memset(buf, 0, se_mem->se_len);
 		kunmap_atomic(buf, KM_IRQ0);
 
@@ -4390,6 +4390,9 @@ transport_generic_get_mem(struct se_cmd *cmd, u32 length, u32 dma_size)
 
 	return 0;
 out:
+	if (se_mem)
+		__free_pages(se_mem->se_page, 0);
+	kmem_cache_free(se_mem_cache, se_mem);
 	return -1;
 }