io_uring/zcrx: rename dma lock

In preparation for reusing the lock for other purposes, rename it to
"pp_lock". As before, it can be taken deeper inside the networking stack
by page pool, and so the syscall io_uring must avoid holding it while
doing queue reconfiguration or anything that can result in immediate pp
init/destruction.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: isilence

io_uring/zcrx.c

@@ -253,7 +253,7 @@ static void io_zcrx_unmap_area(struct io_zcrx_ifq *ifq,
 {
 	int i;
 
-	guard(mutex)(&ifq->dma_lock);
+	guard(mutex)(&ifq->pp_lock);
 	if (!area->is_mapped)
 		return;
 	area->is_mapped = false;
@@ -273,7 +273,7 @@ static int io_zcrx_map_area(struct io_zcrx_ifq *ifq, struct io_zcrx_area *area)
 {
 	int ret;
 
-	guard(mutex)(&ifq->dma_lock);
+	guard(mutex)(&ifq->pp_lock);
 	if (area->is_mapped)
 		return 0;
 
@@ -478,7 +478,7 @@ static struct io_zcrx_ifq *io_zcrx_ifq_alloc(struct io_ring_ctx *ctx)
 	ifq->ctx = ctx;
 	spin_lock_init(&ifq->lock);
 	spin_lock_init(&ifq->rq_lock);
-	mutex_init(&ifq->dma_lock);
+	mutex_init(&ifq->pp_lock);
 	return ifq;
 }
 
@@ -527,7 +527,7 @@ static void io_zcrx_ifq_free(struct io_zcrx_ifq *ifq)
 		put_device(ifq->dev);
 
 	io_free_rbuf_ring(ifq);
-	mutex_destroy(&ifq->dma_lock);
+	mutex_destroy(&ifq->pp_lock);
 	kfree(ifq);
 }
 

io_uring/zcrx.h

@@ -54,7 +54,12 @@ struct io_zcrx_ifq {
 	struct net_device		*netdev;
 	netdevice_tracker		netdev_tracker;
 	spinlock_t			lock;
-	struct mutex			dma_lock;
+
+	/*
+	 * Page pool and net configuration lock, can be taken deeper in the
+	 * net stack.
+	 */
+	struct mutex			pp_lock;
 	struct io_mapped_region		region;
 };