io_uring/zcrx: use guards for locking

Convert last several places using manual locking to guards to simplify
the code.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://patch.msgid.link/eb4667cfaf88c559700f6399da9e434889f5b04a.1774261953.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: isilence

io_uring/zcrx.c

@@ -586,9 +586,8 @@ static void io_zcrx_return_niov_freelist(struct net_iov *niov)
 {
 	struct io_zcrx_area *area = io_zcrx_iov_to_area(niov);
 
-	spin_lock_bh(&area->freelist_lock);
+	guard(spinlock_bh)(&area->freelist_lock);
 	area->freelist[area->free_count++] = net_iov_idx(niov);
-	spin_unlock_bh(&area->freelist_lock);
 }
 
 static void io_zcrx_return_niov(struct net_iov *niov)
@@ -1053,7 +1052,8 @@ static void io_zcrx_refill_slow(struct page_pool *pp, struct io_zcrx_ifq *ifq)
 {
 	struct io_zcrx_area *area = ifq->area;
 
-	spin_lock_bh(&area->freelist_lock);
+	guard(spinlock_bh)(&area->freelist_lock);
+
 	while (area->free_count && pp->alloc.count < PP_ALLOC_CACHE_REFILL) {
 		struct net_iov *niov = __io_zcrx_get_free_niov(area);
 		netmem_ref netmem = net_iov_to_netmem(niov);
@@ -1062,7 +1062,6 @@ static void io_zcrx_refill_slow(struct page_pool *pp, struct io_zcrx_ifq *ifq)
 		io_zcrx_sync_for_device(pp, niov);
 		net_mp_netmem_place_in_cache(pp, netmem);
 	}
-	spin_unlock_bh(&area->freelist_lock);
 }
 
 static netmem_ref io_pp_zc_alloc_netmems(struct page_pool *pp, gfp_t gfp)
@@ -1285,10 +1284,10 @@ static struct net_iov *io_alloc_fallback_niov(struct io_zcrx_ifq *ifq)
 	if (area->mem.is_dmabuf)
 		return NULL;
 
-	spin_lock_bh(&area->freelist_lock);
-	if (area->free_count)
-		niov = __io_zcrx_get_free_niov(area);
-	spin_unlock_bh(&area->freelist_lock);
+	scoped_guard(spinlock_bh, &area->freelist_lock) {
+		if (area->free_count)
+			niov = __io_zcrx_get_free_niov(area);
+	}
 
 	if (niov)
 		page_pool_fragment_netmem(net_iov_to_netmem(niov), 1);