Merge branch 'net-tls-redo-the-RX-resync-locking'

Jakub Kicinski says:

====================
net/tls: redo the RX resync locking

Take two of making sure we don't use a NULL netdev pointer
for RX resync.  This time using a bit and an open coded
wait loop.

v2:
 - fix build warning (DaveM).
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/tls.h b/include/net/tls.h
index 39ea62f0c1f6aef57a3cef401b55959a5ac30f85..4a55ce6a303f54ed5bfd79678093aee552eb186f 100644 (file)
--- a/include/net/tls.h
+++ b/include/net/tls.h
@@ -209,6 +209,10 @@ struct tls_offload_context_tx {
        (ALIGN(sizeof(struct tls_offload_context_tx), sizeof(void *)) +        \
         TLS_DRIVER_STATE_SIZE)
 
+enum tls_context_flags {
+       TLS_RX_SYNC_RUNNING = 0,
+};
+
 struct cipher_context {
        char *iv;
        char *rec_seq;

diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index b95c408fd771452a4ae2f026eb3f6785cf8c89bf..1f9cf57d9754217230f2d25f14baf46404d01165 100644 (file)
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -550,11 +550,23 @@ void tls_device_write_space(struct sock *sk, struct tls_context *ctx)
        }
 }
 
+static void tls_device_resync_rx(struct tls_context *tls_ctx,
+                                struct sock *sk, u32 seq, u64 rcd_sn)
+{
+       struct net_device *netdev;
+
+       if (WARN_ON(test_and_set_bit(TLS_RX_SYNC_RUNNING, &tls_ctx->flags)))
+               return;
+       netdev = READ_ONCE(tls_ctx->netdev);
+       if (netdev)
+               netdev->tlsdev_ops->tls_dev_resync_rx(netdev, sk, seq, rcd_sn);
+       clear_bit_unlock(TLS_RX_SYNC_RUNNING, &tls_ctx->flags);
+}
+
 void handle_device_resync(struct sock *sk, u32 seq, u64 rcd_sn)
 {
        struct tls_context *tls_ctx = tls_get_ctx(sk);
        struct tls_offload_context_rx *rx_ctx;
-       struct net_device *netdev;
        u32 is_req_pending;
        s64 resync_req;
        u32 req_seq;
@@ -570,12 +582,7 @@ void handle_device_resync(struct sock *sk, u32 seq, u64 rcd_sn)
        if (unlikely(is_req_pending) && req_seq == seq &&
            atomic64_try_cmpxchg(&rx_ctx->resync_req, &resync_req, 0)) {
                seq += TLS_HEADER_SIZE - 1;
-               down_read(&device_offload_lock);
-               netdev = tls_ctx->netdev;
-               if (netdev)
-                       netdev->tlsdev_ops->tls_dev_resync_rx(netdev, sk, seq,
-                                                             rcd_sn);
-               up_read(&device_offload_lock);
+               tls_device_resync_rx(tls_ctx, sk, seq, rcd_sn);
        }
 }
 
@@ -977,7 +984,10 @@ static int tls_device_down(struct net_device *netdev)
                if (ctx->rx_conf == TLS_HW)
                        netdev->tlsdev_ops->tls_dev_del(netdev, ctx,
                                                        TLS_OFFLOAD_CTX_DIR_RX);
-               ctx->netdev = NULL;
+               WRITE_ONCE(ctx->netdev, NULL);
+               smp_mb__before_atomic(); /* pairs with test_and_set_bit() */
+               while (test_bit(TLS_RX_SYNC_RUNNING, &ctx->flags))
+                       usleep_range(10, 200);
                dev_put(netdev);
                list_del_init(&ctx->list);