md: remove CONFIG_MULTICORE_RAID456

This doesn't seem to actually help and we have an alternate
multi-threading approach waiting in the wings, so just get
rid of this config option and associated code.

As a bonus, we remove one use of CONFIG_EXPERIMENTAL

Cc: Dan Williams <djbw@fb.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/Kconfig

@@ -154,17 +154,6 @@ config MD_RAID456
 
 	  If unsure, say Y.
 
-config MULTICORE_RAID456
-	bool "RAID-4/RAID-5/RAID-6 Multicore processing (EXPERIMENTAL)"
-	depends on MD_RAID456
-	depends on SMP
-	depends on EXPERIMENTAL
-	---help---
-	  Enable the raid456 module to dispatch per-stripe raid operations to a
-	  thread pool.
-
-	  If unsure, say N.
-
 config MD_MULTIPATH
 	tristate "Multipath I/O support"
 	depends on BLK_DEV_MD

drivers/md/raid5.c

@@ -1406,7 +1406,7 @@ static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu
 			   &sh->ops.zero_sum_result, percpu->spare_page, &submit);
 }
 
-static void __raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
+static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
 {
 	int overlap_clear = 0, i, disks = sh->disks;
 	struct dma_async_tx_descriptor *tx = NULL;
@@ -1471,36 +1471,6 @@ static void __raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
 	put_cpu();
 }
 
-#ifdef CONFIG_MULTICORE_RAID456
-static void async_run_ops(void *param, async_cookie_t cookie)
-{
-	struct stripe_head *sh = param;
-	unsigned long ops_request = sh->ops.request;
-
-	clear_bit_unlock(STRIPE_OPS_REQ_PENDING, &sh->state);
-	wake_up(&sh->ops.wait_for_ops);
-
-	__raid_run_ops(sh, ops_request);
-	release_stripe(sh);
-}
-
-static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
-{
-	/* since handle_stripe can be called outside of raid5d context
-	 * we need to ensure sh->ops.request is de-staged before another
-	 * request arrives
-	 */
-	wait_event(sh->ops.wait_for_ops,
-		   !test_and_set_bit_lock(STRIPE_OPS_REQ_PENDING, &sh->state));
-	sh->ops.request = ops_request;
-
-	atomic_inc(&sh->count);
-	async_schedule(async_run_ops, sh);
-}
-#else
-#define raid_run_ops __raid_run_ops
-#endif
-
 static int grow_one_stripe(struct r5conf *conf)
 {
 	struct stripe_head *sh;
@@ -1509,9 +1479,6 @@ static int grow_one_stripe(struct r5conf *conf)
 		return 0;
 
 	sh->raid_conf = conf;
-	#ifdef CONFIG_MULTICORE_RAID456
-	init_waitqueue_head(&sh->ops.wait_for_ops);
-	#endif
 
 	spin_lock_init(&sh->stripe_lock);
 
@@ -1630,9 +1597,6 @@ static int resize_stripes(struct r5conf *conf, int newsize)
 			break;
 
 		nsh->raid_conf = conf;
-		#ifdef CONFIG_MULTICORE_RAID456
-		init_waitqueue_head(&nsh->ops.wait_for_ops);
-		#endif
 		spin_lock_init(&nsh->stripe_lock);
 
 		list_add(&nsh->lru, &newstripes);