alloc_percpu: add align argument to __alloc_percpu.

This prepares for a real __alloc_percpu, by adding an alignment argument.
Only one place uses __alloc_percpu directly, and that's for a string.

tj: af_inet also uses __alloc_percpu(), update it.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>

block/blktrace.c

@@ -363,7 +363,7 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 	if (!bt->sequence)
 		goto err;
 
-	bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG);
+	bt->msg_data = __alloc_percpu(BLK_TN_MAX_MSG, __alignof__(char));
 	if (!bt->msg_data)
 		goto err;
 

include/linux/percpu.h

@@ -108,9 +108,10 @@ static inline void percpu_free(void *__pdata)
 
 /* (legacy) interface for use without CPU hotplug handling */
 
-#define __alloc_percpu(size)	percpu_alloc_mask((size), GFP_KERNEL, \
+#define __alloc_percpu(size, align)	percpu_alloc_mask((size), GFP_KERNEL, \
 						  cpu_possible_map)
-#define alloc_percpu(type)	(type *)__alloc_percpu(sizeof(type))
+#define alloc_percpu(type)	(type *)__alloc_percpu(sizeof(type), \
+						       __alignof__(type))
 #define free_percpu(ptr)	percpu_free((ptr))
 /*
  * Use this to get to a cpu's version of the per-cpu object dynamically

net/ipv4/af_inet.c

@@ -1375,10 +1375,10 @@ EXPORT_SYMBOL_GPL(snmp_fold_field);
 int snmp_mib_init(void *ptr[2], size_t mibsize)
 {
 	BUG_ON(ptr == NULL);
-	ptr[0] = __alloc_percpu(mibsize);
+	ptr[0] = __alloc_percpu(mibsize, __alignof__(unsigned long long));
 	if (!ptr[0])
 		goto err0;
-	ptr[1] = __alloc_percpu(mibsize);
+	ptr[1] = __alloc_percpu(mibsize, __alignof__(unsigned long long));
 	if (!ptr[1])
 		goto err1;
 	return 0;