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authorThomas Gleixner2007-08-01 17:13:19 +0200
committerLinus Torvalds2007-08-01 20:46:22 -0700
commit0fc4969b866671dfe39b1a9119d0fdc7ea0f63e5 (patch)
tree05e644d8c1e0071b07ac5b6aee83d8dc3eaf664e /kernel/irq
parentfd0cbdd378258fdf44eac5ea091256a4a665315b (diff)
genirq: temporary fix for level-triggered IRQ resend
Marcin Slusarz reported a ne2k-pci "hung network interface" regression. delayed disable relies on the ability to re-trigger the interrupt in the case that a real interrupt happens after the software disable was set. In this case we actually disable the interrupt on the hardware level _after_ it occurred. On enable_irq, we need to re-trigger the interrupt. On i386 this relies on a hardware resend mechanism (send_IPI_self()). Actually we only need the resend for edge type interrupts. Level type interrupts come back once enable_irq() re-enables the interrupt line. I assume that the interrupt in question is level triggered because it is shared and above the legacy irqs 0-15: 17: 12 IO-APIC-fasteoi eth1, eth0 Looking into the IO_APIC code, the resend via send_IPI_self() happens unconditionally. So the resend is done for level and edge interrupts. This makes the problem more mysterious. The code in question lib8390.c does disable_irq(); fiddle_with_the_network_card_hardware() enable_irq(); The fiddle_with_the_network_card_hardware() might cause interrupts, which are cleared in the same code path again, Marcin found that when he disables the irq line on the hardware level (removing the delayed disable) the card is kept alive. So the difference is that we can get a resend on enable_irq, when an interrupt happens during the time, where we are in the disabled region. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/irq')
-rw-r--r--kernel/irq/resend.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/irq/resend.c b/kernel/irq/resend.c
index 5bfeaed7e487..c38272746887 100644
--- a/kernel/irq/resend.c
+++ b/kernel/irq/resend.c
@@ -62,6 +62,15 @@ void check_irq_resend(struct irq_desc *desc, unsigned int irq)
*/
desc->chip->enable(irq);
+ /*
+ * Temporary hack to figure out more about the problem, which
+ * is causing the ancient network cards to die.
+ */
+ if (desc->handle_irq != handle_edge_irq) {
+ WARN_ON_ONCE(1);
+ return;
+ }
+
if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
desc->status = (status & ~IRQ_PENDING) | IRQ_REPLAY;