From 1349a457e5e33580fb26afab087e6b932b1a4372 Mon Sep 17 00:00:00 2001 From: Mans Rullgard Date: Thu, 24 Nov 2016 18:46:41 +0000 Subject: [PATCH 15/32] ivshmem-net: fix race in state machine --- drivers/net/ivshmem-net.c | 60 ++++++++++++++++++++++++----------------------- 1 file changed, 31 insertions(+), 29 deletions(-) diff --git a/drivers/net/ivshmem-net.c b/drivers/net/ivshmem-net.c index a535cb71adde..acd00e47acd7 100644 --- 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; } -- 2.11.0