From 4bb073c0e32a0862bdb5215d11af19f6c0180c98 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Thu, 12 Jun 2008 02:22:02 -0700 Subject: [PATCH] net: Eliminate flush_scheduled_work() calls while RTNL is held. If the RTNL is held when we invoke flush_scheduled_work() we could deadlock. One such case is linkwatch, it is a work struct which tries to grab the RTNL semaphore. The most common case are net driver ->stop() methods. The simplest conversion is to instead use cancel_{delayed_}work_sync() explicitly on the various work struct the driver uses. This is an OK transformation because these work structs are doing things like resetting the chip, restarting link negotiation, and so forth. And if we're bringing down the device, we're about to turn the chip off and reset it anways. So if we cancel a pending work event, that's fine here. Some drivers were working around this deadlock by using a msleep() polling loop of some sort, and those cases are converted to instead use cancel_{delayed_}work_sync() as well. Signed-off-by: David S. Miller --- drivers/net/bnx2.c | 9 +-------- drivers/net/bnx2.h | 1 - drivers/net/ehea/ehea_main.c | 3 ++- drivers/net/hamradio/baycom_epp.c | 2 +- drivers/net/smc911x.c | 24 +++++------------------ drivers/net/smc91x.c | 17 +++------------- drivers/net/tulip/tulip_core.c | 2 +- drivers/net/usb/kaweth.c | 2 +- drivers/net/wireless/hostap/hostap_main.c | 8 +++++++- 9 files changed, 21 insertions(+), 47 deletions(-) diff --git a/drivers/net/bnx2.c b/drivers/net/bnx2.c index 4b46e68183..367b6d4627 100644 --- a/drivers/net/bnx2.c +++ b/drivers/net/bnx2.c @@ -5724,14 +5724,12 @@ bnx2_reset_task(struct work_struct *work) if (!netif_running(bp->dev)) return; - bp->in_reset_task = 1; bnx2_netif_stop(bp); bnx2_init_nic(bp); atomic_set(&bp->intr_sem, 1); bnx2_netif_start(bp); - bp->in_reset_task = 0; } static void @@ -5907,12 +5905,7 @@ bnx2_close(struct net_device *dev) struct bnx2 *bp = netdev_priv(dev); u32 reset_code; - /* Calling flush_scheduled_work() may deadlock because - * linkwatch_event() may be on the workqueue and it will try to get - * the rtnl_lock which we are holding. - */ - while (bp->in_reset_task) - msleep(1); + cancel_work_sync(&bp->reset_task); bnx2_disable_int_sync(bp); bnx2_napi_disable(bp); diff --git a/drivers/net/bnx2.h b/drivers/net/bnx2.h index 1eaf5bb3d9..2377cc13bf 100644 --- a/drivers/net/bnx2.h +++ b/drivers/net/bnx2.h @@ -6656,7 +6656,6 @@ struct bnx2 { int current_interval; struct timer_list timer; struct work_struct reset_task; - int in_reset_task; /* Used to synchronize phy accesses. */ spinlock_t phy_lock; diff --git a/drivers/net/ehea/ehea_main.c b/drivers/net/ehea/ehea_main.c index faae01dc1c..075fd54742 100644 --- a/drivers/net/ehea/ehea_main.c +++ b/drivers/net/ehea/ehea_main.c @@ -2605,7 +2605,8 @@ static int ehea_stop(struct net_device *dev) if (netif_msg_ifdown(port)) ehea_info("disabling port %s", dev->name); - flush_scheduled_work(); + cancel_work_sync(&port->reset_task); + mutex_lock(&port->port_lock); netif_stop_queue(dev); port_napi_disable(port); diff --git a/drivers/net/hamradio/baycom_epp.c b/drivers/net/hamradio/baycom_epp.c index dde9c7e640..00bc7fbb6b 100644 --- a/drivers/net/hamradio/baycom_epp.c +++ b/drivers/net/hamradio/baycom_epp.c @@ -959,7 +959,7 @@ static int epp_close(struct net_device *dev) unsigned char tmp[1]; bc->work_running = 0; - flush_scheduled_work(); + cancel_delayed_work_sync(&bc->run_work); bc->stat = EPP_DCDBIT; tmp[0] = 0; pp->ops->epp_write_addr(pp, tmp, 1, 0); diff --git a/drivers/net/smc911x.c b/drivers/net/smc911x.c index 4e28002051..e2ee91a6ae 100644 --- a/drivers/net/smc911x.c +++ b/drivers/net/smc911x.c @@ -136,7 +136,6 @@ struct smc911x_local { /* work queue */ struct work_struct phy_configure; - int work_pending; int tx_throttle; spinlock_t lock; @@ -960,11 +959,11 @@ static void smc911x_phy_configure(struct work_struct *work) * We should not be called if phy_type is zero. */ if (lp->phy_type == 0) - goto smc911x_phy_configure_exit_nolock; + return; if (smc911x_phy_reset(dev, phyaddr)) { printk("%s: PHY reset timed out\n", dev->name); - goto smc911x_phy_configure_exit_nolock; + return; } spin_lock_irqsave(&lp->lock, flags); @@ -1033,8 +1032,6 @@ static void smc911x_phy_configure(struct work_struct *work) smc911x_phy_configure_exit: spin_unlock_irqrestore(&lp->lock, flags); -smc911x_phy_configure_exit_nolock: - lp->work_pending = 0; } /* @@ -1356,11 +1353,8 @@ static void smc911x_timeout(struct net_device *dev) * smc911x_phy_configure() calls msleep() which calls schedule_timeout() * which calls schedule(). Hence we use a work queue. */ - if (lp->phy_type != 0) { - if (schedule_work(&lp->phy_configure)) { - lp->work_pending = 1; - } - } + if (lp->phy_type != 0) + schedule_work(&lp->phy_configure); /* We can accept TX packets again */ dev->trans_start = jiffies; @@ -1531,16 +1525,8 @@ static int smc911x_close(struct net_device *dev) if (lp->phy_type != 0) { /* We need to ensure that no calls to * smc911x_phy_configure are pending. - - * flush_scheduled_work() cannot be called because we - * are running with the netlink semaphore held (from - * devinet_ioctl()) and the pending work queue - * contains linkwatch_event() (scheduled by - * netif_carrier_off() above). linkwatch_event() also - * wants the netlink semaphore. */ - while (lp->work_pending) - schedule(); + cancel_work_sync(&lp->phy_configure); smc911x_phy_powerdown(dev, lp->mii.phy_id); } diff --git a/drivers/net/smc91x.c b/drivers/net/smc91x.c index a188e33484..f2051b209d 100644 --- a/drivers/net/smc91x.c +++ b/drivers/net/smc91x.c @@ -1016,15 +1016,8 @@ static void smc_phy_powerdown(struct net_device *dev) /* We need to ensure that no calls to smc_phy_configure are pending. - - flush_scheduled_work() cannot be called because we are - running with the netlink semaphore held (from - devinet_ioctl()) and the pending work queue contains - linkwatch_event() (scheduled by netif_carrier_off() - above). linkwatch_event() also wants the netlink semaphore. */ - while(lp->work_pending) - yield(); + cancel_work_sync(&lp->phy_configure); bmcr = smc_phy_read(dev, phy, MII_BMCR); smc_phy_write(dev, phy, MII_BMCR, bmcr | BMCR_PDOWN); @@ -1161,7 +1154,6 @@ static void smc_phy_configure(struct work_struct *work) smc_phy_configure_exit: SMC_SELECT_BANK(lp, 2); spin_unlock_irq(&lp->lock); - lp->work_pending = 0; } /* @@ -1389,11 +1381,8 @@ static void smc_timeout(struct net_device *dev) * smc_phy_configure() calls msleep() which calls schedule_timeout() * which calls schedule(). Hence we use a work queue. */ - if (lp->phy_type != 0) { - if (schedule_work(&lp->phy_configure)) { - lp->work_pending = 1; - } - } + if (lp->phy_type != 0) + schedule_work(&lp->phy_configure); /* We can accept TX packets again */ dev->trans_start = jiffies; diff --git a/drivers/net/tulip/tulip_core.c b/drivers/net/tulip/tulip_core.c index 55670b5eb6..af8d2c436e 100644 --- a/drivers/net/tulip/tulip_core.c +++ b/drivers/net/tulip/tulip_core.c @@ -731,7 +731,7 @@ static void tulip_down (struct net_device *dev) void __iomem *ioaddr = tp->base_addr; unsigned long flags; - flush_scheduled_work(); + cancel_work_sync(&tp->media_work); #ifdef CONFIG_TULIP_NAPI napi_disable(&tp->napi); diff --git a/drivers/net/usb/kaweth.c b/drivers/net/usb/kaweth.c index 0dcfc03102..7c66b052f5 100644 --- a/drivers/net/usb/kaweth.c +++ b/drivers/net/usb/kaweth.c @@ -706,7 +706,7 @@ static void kaweth_kill_urbs(struct kaweth_device *kaweth) usb_kill_urb(kaweth->rx_urb); usb_kill_urb(kaweth->tx_urb); - flush_scheduled_work(); + cancel_delayed_work_sync(&kaweth->lowmem_work); /* a scheduled work may have resubmitted, we hit them again */ diff --git a/drivers/net/wireless/hostap/hostap_main.c b/drivers/net/wireless/hostap/hostap_main.c index 20d387f665..f7aec9309d 100644 --- a/drivers/net/wireless/hostap/hostap_main.c +++ b/drivers/net/wireless/hostap/hostap_main.c @@ -682,7 +682,13 @@ static int prism2_close(struct net_device *dev) netif_device_detach(dev); } - flush_scheduled_work(); + cancel_work_sync(&local->reset_queue); + cancel_work_sync(&local->set_multicast_list_queue); + cancel_work_sync(&local->set_tim_queue); +#ifndef PRISM2_NO_STATION_MODES + cancel_work_sync(&local->info_queue); +#endif + cancel_work_sync(&local->comms_qual_update); module_put(local->hw_module); -- 2.39.5