The patch titled uml: IRQ register race condition has been removed from the -mm tree. Its filename was uml-irq-register-race-condition.patch This patch was dropped because it was nacked The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: uml: IRQ register race condition From: Andrew Lunn <andrew@xxxxxxx> There is a race condition in um_request_irq(). The SIGIO handling is first enabled with the call to activate_fd(). The irq handler is then registered with request_irq(). What can happen is that directly after activate_fd() the SIGIO goes off and the IRQ source is disabled at the low level, the pollfd is set to -1. Since no irq handler has yet been registered, the interrupt it left disabled at the low level. The interrupt handler is then registered, but its too late, the interrupt source has been disabled at the lower level and is never re-enabled. To fix this race condition i swapped the order. First request_irq() then activate_fd() the interrupt sources. There is a second bug. In 2.6.31 there was a change to the way __do_IRQ() and friends work for chained interrupt sources. The old way was that all chained interrupt handlers were called. The new way is that the chain is walked only until a handler returns IRQ_HANDLED or IRQ_WAKE_THREAD. uml_net_interrupt() would always return IRQ_HANDLED, irrespective of if the device really did receive an interrupt or not. This mean with the new code only the first device on a chained interrupt ever got its interrupts handled. The second/third/... device never got any interrupts processed. I changed uml_net_interrupt() to always return IRQ_NONE so that all handlers get called on a chained interrupt. Signed-off-by: Andrew Lunn <andrew@xxxxxxx> Cc: Jeff Dike <jdike@xxxxxxxxxxx> Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Yinghai Lu <yinghai@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- diff -puN arch/um/drivers/net_kern.c~uml-irq-register-race-condition arch/um/drivers/net_kern.c --- a/arch/um/drivers/net_kern.c~uml-irq-register-race-condition +++ a/arch/um/drivers/net_kern.c @@ -145,7 +145,7 @@ static irqreturn_t uml_net_interrupt(int out: spin_unlock(&lp->lock); - return IRQ_HANDLED; + return IRQ_NONE; } static int uml_net_open(struct net_device *dev) diff -puN arch/um/kernel/irq.c~uml-irq-register-race-condition arch/um/kernel/irq.c --- a/arch/um/kernel/irq.c~uml-irq-register-race-condition +++ a/arch/um/kernel/irq.c @@ -346,13 +346,12 @@ int um_request_irq(unsigned int irq, int { int err; - if (fd != -1) { + err = request_irq(irq, handler, irqflags, devname, dev_id); + + if (!err && (fd != -1)) err = activate_fd(irq, fd, type, dev_id); - if (err) - return err; - } - return request_irq(irq, handler, irqflags, devname, dev_id); + return err; } EXPORT_SYMBOL(um_request_irq); _ Patches currently in -mm which might be from andrew@xxxxxxx are linux-next.patch uml-irq-register-race-condition.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html