ivshmem-net: fix race in state machine

(cherry picked from commit 615bca5306e422b633c0ff6296077da4469a4b27)
(cherry picked from commit 139f14253d76fa593299a416c6916e01862a7e15)
Signed-off-by: Vipul Kumar <vipul_kumar@mentor.com>

diff --git a/drivers/net/ivshmem-net.c b/drivers/net/ivshmem-net.c
index a535cb7..acd00e4 100644 (file)
--- a/drivers/net/ivshmem-net.c
+++ b/drivers/net/ivshmem-net.c
@@ -36,6 +36,8 @@
 #define IVSHM_NET_STATE_READY  2
 #define IVSHM_NET_STATE_RUN    3
 
+#define IVSHM_NET_FLAG_RUN     0
+
 #define IVSHM_NET_MTU_MIN 256
 #define IVSHM_NET_MTU_MAX 65535
 #define IVSHM_NET_MTU_DEF 16384
@@ -96,6 +98,8 @@ struct ivshm_net {
        u32 lstate;
        u32 rstate;
 
+       unsigned long flags;
+
        struct workqueue_struct *state_wq;
        struct work_struct state_work;
 
@@ -529,12 +533,32 @@ static void ivshm_net_run(struct net_device *ndev)
 {
        struct ivshm_net *in = netdev_priv(ndev);
 
+       if (in->lstate < IVSHM_NET_STATE_READY)
+               return;
+
+       if (!netif_running(ndev))
+               return;
+
+       if (test_and_set_bit(IVSHM_NET_FLAG_RUN, &in->flags))
+               return;
+
        netif_start_queue(ndev);
        napi_enable(&in->napi);
        napi_schedule(&in->napi);
        ivshm_net_set_state(in, IVSHM_NET_STATE_RUN);
 }
 
+static void ivshm_net_do_stop(struct net_device *ndev)
+{
+       struct ivshm_net *in = netdev_priv(ndev);
+
+       if (!test_and_clear_bit(IVSHM_NET_FLAG_RUN, &in->flags))
+               return;
+
+       netif_stop_queue(ndev);
+       napi_disable(&in->napi);
+}
+
 static void ivshm_net_state_change(struct work_struct *work)
 {
        struct ivshm_net *in = container_of(work, struct ivshm_net, state_work);
@@ -560,21 +584,13 @@ static void ivshm_net_state_change(struct work_struct *work)
                break;
 
        case IVSHM_NET_STATE_READY:
+       case IVSHM_NET_STATE_RUN:
                if (rstate >= IVSHM_NET_STATE_READY) {
                        netif_carrier_on(ndev);
-                       if (ndev->flags & IFF_UP)
-                               ivshm_net_run(ndev);
+                       ivshm_net_run(ndev);
                } else {
                        netif_carrier_off(ndev);
-                       ivshm_net_set_state(in, IVSHM_NET_STATE_RESET);
-               }
-               break;
-
-       case IVSHM_NET_STATE_RUN:
-               if (rstate < IVSHM_NET_STATE_READY) {
-                       netif_stop_queue(ndev);
-                       napi_disable(&in->napi);
-                       netif_carrier_off(ndev);
+                       ivshm_net_do_stop(ndev);
                        ivshm_net_set_state(in, IVSHM_NET_STATE_RESET);
                }
                break;
@@ -584,18 +600,13 @@ static void ivshm_net_state_change(struct work_struct *work)
        WRITE_ONCE(in->rstate, rstate);
 }
 
-static bool ivshm_net_check_state(struct net_device *ndev)
+static void ivshm_net_check_state(struct net_device *ndev)
 {
        struct ivshm_net *in = netdev_priv(ndev);
        u32 rstate = readl(&in->ivshm_regs->rstate);
 
-       if (rstate != READ_ONCE(in->rstate) ||
-           in->lstate != IVSHM_NET_STATE_RUN) {
+       if (rstate != in->rstate || !test_bit(IVSHM_NET_FLAG_RUN, &in->flags))
                queue_work(in->state_wq, &in->state_work);
-               return false;
-       }
-
-       return true;
 }
 
 static irqreturn_t ivshm_net_int(int irq, void *data)
@@ -617,24 +628,15 @@ static int ivshm_net_open(struct net_device *ndev)
 
        netdev_reset_queue(ndev);
        ndev->operstate = IF_OPER_UP;
-
-       if (in->lstate == IVSHM_NET_STATE_READY)
-               ivshm_net_run(ndev);
+       ivshm_net_run(ndev);
 
        return 0;
 }
 
 static int ivshm_net_stop(struct net_device *ndev)
 {
-       struct ivshm_net *in = netdev_priv(ndev);
-
        ndev->operstate = IF_OPER_DOWN;
-
-       if (in->lstate == IVSHM_NET_STATE_RUN) {
-               napi_disable(&in->napi);
-               netif_stop_queue(ndev);
-               ivshm_net_set_state(in, IVSHM_NET_STATE_READY);
-       }
+       ivshm_net_do_stop(ndev);
 
        return 0;
 }