From: Paolo 'Blaisorblade' Giarrusso 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 --- arch/um/drivers/net_kern.c | 16 ++++------------ 1 files changed, 4 insertions(+), 12 deletions(-) diff -puN arch/um/drivers/net_kern.c~uml-fix-proc-vs-interrupt-context-spinlock-deadlock arch/um/drivers/net_kern.c --- a/arch/um/drivers/net_kern.c~uml-fix-proc-vs-interrupt-context-spinlock-deadlock +++ a/arch/um/drivers/net_kern.c @@ -114,8 +114,6 @@ static int uml_net_open(struct net_devic 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_devic */ 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_devi 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_de 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 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 dev->mtu = new_mtu; out: - spin_unlock(&lp->lock); + spin_unlock_irq(&lp->lock); return err; } _