Revert "tun/tap: add ptr_ring consume helper with netdev queue wakeup"

This reverts commit d4c22d70d7253dd727c71484c58d504f6c630343.

There is no netdev queue left to wake after reverting
commit 1d6e569b7d0c ("tun/tap & vhost-net: avoid ptr_ring tail-drop
when a qdisc is present").

Signed-off-by: Simon Schippers <simon.schippers@tu-dortmund.de>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://patch.msgid.link/20260728092240.250257-5-simon.schippers@tu-dortmund.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 39abc3078097c2c60264f8c84b24a1c02f5a0619..fed9dfdfcc3bc093970db57392ead13a5bc3fb69 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -145,8 +145,6 @@ struct tun_file {
        struct list_head next;
        struct tun_struct *detached;
        struct ptr_ring tx_ring;
-       /* Protected by tx_ring.consumer_lock */
-       int cons_cnt;
        struct xdp_rxq_info xdp_rxq;
 };
 
@@ -590,13 +588,8 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
                rcu_assign_pointer(tun->tfiles[index],
                                   tun->tfiles[tun->numqueues - 1]);
                ntfile = rtnl_dereference(tun->tfiles[index]);
-               spin_lock(&ntfile->tx_ring.consumer_lock);
                ntfile->queue_index = index;
                ntfile->xdp_rxq.queue_index = index;
-               ntfile->cons_cnt = 0;
-               if (__ptr_ring_empty(&ntfile->tx_ring))
-                       netif_wake_subqueue(tun->dev, index);
-               spin_unlock(&ntfile->tx_ring.consumer_lock);
                rcu_assign_pointer(tun->tfiles[tun->numqueues - 1],
                                   NULL);
 
@@ -737,9 +730,6 @@ static int tun_attach(struct tun_struct *tun, struct file *file,
                goto out;
        }
 
-       spin_lock(&tfile->tx_ring.consumer_lock);
-       tfile->cons_cnt = 0;
-       spin_unlock(&tfile->tx_ring.consumer_lock);
        tfile->queue_index = tun->numqueues;
        tfile->socket.sk->sk_shutdown &= ~RCV_SHUTDOWN;
 
@@ -2126,46 +2116,13 @@ done:
        return total;
 }
 
-/* Callers must hold ring.consumer_lock */
-static void __tun_wake_queue(struct tun_struct *tun,
-                            struct tun_file *tfile, int consumed)
-{
-       struct netdev_queue *txq = netdev_get_tx_queue(tun->dev,
-                                               tfile->queue_index);
-
-       /* Paired with smp_mb__after_atomic() in tun_net_xmit() */
-       smp_mb();
-       if (netif_tx_queue_stopped(txq)) {
-               tfile->cons_cnt += consumed;
-               if (tfile->cons_cnt >= tfile->tx_ring.size / 2 ||
-                   __ptr_ring_empty(&tfile->tx_ring)) {
-                       netif_tx_wake_queue(txq);
-                       tfile->cons_cnt = 0;
-               }
-       }
-}
-
-static void *tun_ring_consume(struct tun_struct *tun, struct tun_file *tfile)
-{
-       void *ptr;
-
-       spin_lock(&tfile->tx_ring.consumer_lock);
-       ptr = __ptr_ring_consume(&tfile->tx_ring);
-       if (ptr)
-               __tun_wake_queue(tun, tfile, 1);
-
-       spin_unlock(&tfile->tx_ring.consumer_lock);
-       return ptr;
-}
-
-static void *tun_ring_recv(struct tun_struct *tun, struct tun_file *tfile,
-                          int noblock, int *err)
+static void *tun_ring_recv(struct tun_file *tfile, int noblock, int *err)
 {
        DECLARE_WAITQUEUE(wait, current);
        void *ptr = NULL;
        int error = 0;
 
-       ptr = tun_ring_consume(tun, tfile);
+       ptr = ptr_ring_consume(&tfile->tx_ring);
        if (ptr)
                goto out;
        if (noblock) {
@@ -2177,7 +2134,7 @@ static void *tun_ring_recv(struct tun_struct *tun, struct tun_file *tfile,
 
        while (1) {
                set_current_state(TASK_INTERRUPTIBLE);
-               ptr = tun_ring_consume(tun, tfile);
+               ptr = ptr_ring_consume(&tfile->tx_ring);
                if (ptr)
                        break;
                if (signal_pending(current)) {
@@ -2214,7 +2171,7 @@ static ssize_t tun_do_read(struct tun_struct *tun, struct tun_file *tfile,
 
        if (!ptr) {
                /* Read frames from ring */
-               ptr = tun_ring_recv(tun, tfile, noblock, &err);
+               ptr = tun_ring_recv(tfile, noblock, &err);
                if (!ptr)
                        return err;
        }
@@ -3669,16 +3626,6 @@ static int tun_queue_resize(struct tun_struct *tun)
                                          dev->tx_queue_len, GFP_KERNEL,
                                          tun_ptr_free);
 
-       if (!ret) {
-               for (i = 0; i < tun->numqueues; i++) {
-                       tfile = rtnl_dereference(tun->tfiles[i]);
-                       spin_lock(&tfile->tx_ring.consumer_lock);
-                       netif_wake_subqueue(tun->dev, tfile->queue_index);
-                       tfile->cons_cnt = 0;
-                       spin_unlock(&tfile->tx_ring.consumer_lock);
-               }
-       }
-
        kfree(rings);
        return ret;
 }