From 48af05ed54ddf8dc6eceea4f009e063d7e784b37 Mon Sep 17 00:00:00 2001 From: Paolo 'Blaisorblade' Giarrusso Date: Wed, 27 Sep 2006 01:50:31 -0700 Subject: [PATCH] [PATCH] uml: fix proc-vs-interrupt context spinlock deadlock This spinlock can be taken on interrupt too, so spin_lock_irq[save] must be used. However, Documentation/networking/netdevices.txt explains we are called with rtnl_lock() held - so we don't need to care about other concurrent opens. Verified also in LDD3 and by direct checking. Also verified that the network layer (through a state machine) guarantees us that nobody will close the interface while it's being used. Please correct me if I'm wrong. Also, we must check we don't sleep with irqs disabled!!! But anyway, this is not news - we already can't sleep while holding a spinlock. Who says this is guaranted really by the present code? Signed-off-by: Paolo 'Blaisorblade' Giarrusso Cc: Jeff Dike Cc: Jeff Garzik Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/drivers/net_kern.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c index 4a7966b21931..657dfacd5ba8 100644 --- a/arch/um/drivers/net_kern.c +++ b/arch/um/drivers/net_kern.c @@ -114,8 +114,6 @@ static int uml_net_open(struct net_device *dev) struct uml_net_private *lp = dev->priv; int err; - spin_lock(&lp->lock); - if(lp->fd >= 0){ err = -ENXIO; goto out; @@ -149,8 +147,6 @@ static int uml_net_open(struct net_device *dev) */ while((err = uml_net_rx(dev)) > 0) ; - spin_unlock(&lp->lock); - spin_lock(&opened_lock); list_add(&lp->list, &opened); spin_unlock(&opened_lock); @@ -160,7 +156,6 @@ out_close: if(lp->close != NULL) (*lp->close)(lp->fd, &lp->user); lp->fd = -1; out: - spin_unlock(&lp->lock); return err; } @@ -169,15 +164,12 @@ static int uml_net_close(struct net_device *dev) struct uml_net_private *lp = dev->priv; netif_stop_queue(dev); - spin_lock(&lp->lock); free_irq(dev->irq, dev); if(lp->close != NULL) (*lp->close)(lp->fd, &lp->user); lp->fd = -1; - spin_unlock(&lp->lock); - spin_lock(&opened_lock); list_del(&lp->list); spin_unlock(&opened_lock); @@ -246,9 +238,9 @@ static int uml_net_set_mac(struct net_device *dev, void *addr) struct uml_net_private *lp = dev->priv; struct sockaddr *hwaddr = addr; - spin_lock(&lp->lock); + spin_lock_irq(&lp->lock); set_ether_mac(dev, hwaddr->sa_data); - spin_unlock(&lp->lock); + spin_unlock_irq(&lp->lock); return(0); } @@ -258,7 +250,7 @@ static int uml_net_change_mtu(struct net_device *dev, int new_mtu) struct uml_net_private *lp = dev->priv; int err = 0; - spin_lock(&lp->lock); + spin_lock_irq(&lp->lock); new_mtu = (*lp->set_mtu)(new_mtu, &lp->user); if(new_mtu < 0){ @@ -269,7 +261,7 @@ static int uml_net_change_mtu(struct net_device *dev, int new_mtu) dev->mtu = new_mtu; out: - spin_unlock(&lp->lock); + spin_unlock_irq(&lp->lock); return err; }