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From 0af5d7d021bb899d9c3880415267e178a20fb7a9 Mon Sep 17 00:00:00 2001
From: Mans Rullgard <mans@mansr.com>
Date: Thu, 24 Nov 2016 18:46:41 +0000
Subject: [PATCH] ivshmem-net: fix race in state machine
(cherry picked from commit 5d663baed6a89d09bae4446f6509f9957c780bc7)
---
drivers/net/ivshmem-net.c | 60 ++++++++++++++++++++++++-----------------------
1 file changed, 31 insertions(+), 29 deletions(-)
--- 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_dev
{
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(struc
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(struc
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_dev
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;
}
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