Re: [PATCH 1/1] via-rhine: Fix hanging with high CPU load on low-end broads.
From: Ben Hutchings <hidden>
Date: 2011-12-28 14:37:49
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On Wed, 2011-12-28 at 12:28 +0000, Bjarke Istrup Pedersen wrote:
Working around problem causing high CPU load and hanging system when there is alot of network trafic. It is kind of an ugly way to work around it, but it allows the Soekris net5501 to have trafic between two of it's NICs without hanging so much that the watchdog kicks in and does a hard reboot of the system. There is more info on the problem here: http://http://lists.soekris.com/pipermail/soekris-tech/2010-October/016889.html Tested with positive results on two Soekris net5501-70 boxes.
This is completely wrong. In a UP configuration the extra spinlock calls have no effect (except perhaps a small delay). In an SMP configuration they will cause rhine_tx() to deadlock when it also tries to acquire the spinlock. Ben. [...]
quoted hunk ↗ jump to hunk
diff --git a/drivers/net/ethernet/via/via-rhine.c b/drivers/net/ethernet/via/via-rhine.c index f34dd99..8c77dcd 100644 --- a/drivers/net/ethernet/via/via-rhine.c +++ b/drivers/net/ethernet/via/via-rhine.c@@ -1567,6 +1567,9 @@ static irqreturn_t rhine_interrupt(int irq, void *dev_instance) int boguscnt = max_interrupt_work; int handled = 0; + if (!spin_trylock(&rp->lock)) + return IRQ_RETVAL(handled); + while ((intr_status = get_intr_status(dev))) { handled = 1;@@ -1616,6 +1619,8 @@ static irqreturn_t rhine_interrupt(int irq, void *dev_instance) } } + spin_unlock(&rp->lock); + if (debug > 3) netdev_dbg(dev, "exiting interrupt, status=%08x\n", ioread16(ioaddr + IntrStatus));
-- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.