io_uring/zcrx: fix rq flush locking

zcrx needs to keep the rq lock for uref manipulations, for now move all
zcrx_return_buffers() under the lock.

Fixes: 475eb39 ("io_uring/zcrx: add sync refill queue flushing")
Signed-off-by: Pavel Begunkov <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

Author: isilence

io_uring/zcrx.c

@@ -1069,8 +1069,6 @@ static unsigned zcrx_parse_rq(netmem_ref *netmem_array, unsigned nr,
 	unsigned int mask = zcrx->rq_entries - 1;
 	unsigned int i;
 
-	guard(spinlock_bh)(&zcrx->rq_lock);
-
 	nr = min(nr, io_zcrx_rqring_entries(zcrx));
 	for (i = 0; i < nr; i++) {
 		struct io_uring_zcrx_rqe *rqe = io_zcrx_get_rqe(zcrx, mask);
@@ -1115,9 +1113,11 @@ static int zcrx_flush_rq(struct io_ring_ctx *ctx, struct io_zcrx_ifq *zcrx,
 		return -EINVAL;
 
 	do {
-		nr = zcrx_parse_rq(netmems, ZCRX_FLUSH_BATCH, zcrx);
+		scoped_guard(spinlock_bh, &zcrx->rq_lock) {
+			nr = zcrx_parse_rq(netmems, ZCRX_FLUSH_BATCH, zcrx);
+			zcrx_return_buffers(netmems, nr);
+		}
 
-		zcrx_return_buffers(netmems, nr);
 		total += nr;
 
 		if (fatal_signal_pending(current))