USB: xhci-mem.c: introduce missing kfree

Error handling code following a kzalloc should free the allocated data.

The semantic match that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@r exists@
local idexpression x;
statement S;
expression E;
identifier f,f1,l;
position p1,p2;
expression *ptr != NULL;
@@

x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
<... when != x
     when != if (...) { <+...x...+> }
(
x->f1 = E
|
 (x->f1 == NULL || ...)
|
 f(...,x->f1,...)
)
...>
(
 return \(0\|<+...x...+>\|ptr\);
|
 return@p2 ...;
)

@script:python@
p1 << r.p1;
p2 << r.p2;
@@

print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Acked-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/xhci-mem.c

@@ -779,14 +779,17 @@ struct xhci_command *xhci_alloc_command(struct xhci_hcd *xhci,
 
 	command->in_ctx =
 		xhci_alloc_container_ctx(xhci, XHCI_CTX_TYPE_INPUT, mem_flags);
-	if (!command->in_ctx)
+	if (!command->in_ctx) {
+		kfree(command);
 		return NULL;
+	}
 
 	if (allocate_completion) {
 		command->completion =
 			kzalloc(sizeof(struct completion), mem_flags);
 		if (!command->completion) {
 			xhci_free_container_ctx(xhci, command->in_ctx);
+			kfree(command);
 			return NULL;
 		}
 		init_completion(command->completion);