Messages in this thread | | | Date | Thu, 02 Jul 2009 13:29:35 -0400 | From | Ayaz Abdulla <> | Subject | Re: [GIT]: Networking |
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Eric Dumazet wrote: > Ayaz Abdulla a écrit : > >> >>Eric Dumazet wrote: >> >>>Eric Dumazet a écrit : >>> >>> >>>>Ingo Molnar a écrit : >>>> >>>> >>>>>>The following changes since commit >>>>>>52989765629e7d182b4f146050ebba0abf2cb0b7: >>>>>> Linus Torvalds (1): >>>>>> Merge git://git.kernel.org/.../davem/net-2.6 >>>>>> >>>>>>are available in the git repository at: >>>>>> >>>>>> master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6.git master >>>>> >>>>>Hm, something in this lot quickly wrecked networking here - see the >>>>>tx timeout dump below. It starts with: >>>>> >>>>>[ 351.004596] WARNING: at net/sched/sch_generic.c:246 >>>>>dev_watchdog+0x10b/0x19c() >>>>>[ 351.011815] Hardware name: System Product Name >>>>>[ 351.016220] NETDEV WATCHDOG: eth0 (forcedeth): transmit queue 0 >>>>>timed out >>>>> >>>>>Config attached. Unfortunately i've got no time to do bisection today. >>>> >>>> >>>> >>>>forcedeth might have a problem, in its netif_wake_queue() logic, but >>>>I could not see why a recent patch could make this problem visible now. >>>> >>>>CPU0/1: AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ stepping 02 >>>>is not a new cpu either :) >>>> >>>>forcedeth uses an internal tx_stop without appropriate barrier. >>>> >>>>Could you try following patch ? >>>> >>>>(random guess as I dont have much time right now) >>> >>> >>>Oh well this patch was soooo stupid, sorry Ingo. >>> >>> >>>We might have a race in napi_schedule(), leaving interrupts disabled >>>forever. >>>I cannot test this patch, I dont have the hardware... >>> >>>Thanks >>> >>>diff --git a/drivers/net/forcedeth.c b/drivers/net/forcedeth.c >>>index 1094d29..3b4e076 100644 >>>--- a/drivers/net/forcedeth.c >>>+++ b/drivers/net/forcedeth.c >>>@@ -3514,11 +3514,13 @@ static irqreturn_t nv_nic_irq(int foo, void >>>*data) >>> nv_msi_workaround(np); >>> >>> #ifdef CONFIG_FORCEDETH_NAPI >>>- napi_schedule(&np->napi); >>>- >>>- /* Disable furthur irq's >>>- (msix not enabled with napi) */ >>>- writel(0, base + NvRegIrqMask); >>>+ if (napi_schedule_prep(&np->napi)) { >>>+ /* >>>+ * Disable further irq's (msix not enabled with napi) >>>+ */ >>>+ writel(0, base + NvRegIrqMask); >>>+ __napi_schedule(&np->napi); >>>+ } >> >>Yes, good catch. There is a race condition here with napi poll. >> >>I would prefer to do the following to keep the code simple and clean. >> >>writel(0, base + NvRegIrqMask); >>napi_schedule(&np->napi); > > > > CC trimmed down to network devs only :) > > It would be racy too ... > > check drivers/net/amd8111e.c, drivers/net/natsemi.c ... > > If this cpu inconditionaly calls writel(0, base + NvRegIrqMask); > while another cpu just called writel(np->irqmask, base + NvRegIrqMask), > we end with disabled interrupts ? <BCC linux-kernel>
Yes, but the next instruction is to call napi_schedule() which will re-enable interrupts in napi function.
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