The driver attempts to select an IRQ for the NIC automatically by
testing which of the supported IRQs are available and then probing
each available IRQ with probe_irq_{on,off}(). There are obvious race
conditions here, besides which:
1. The test for availability is done by passing a NULL handler, which
now always returns -EINVAL, thus the device cannot be opened:
<http://bugs.debian.org/566522>
2. probe_irq_off() will report only the first ISA IRQ handled,
potentially leading to a false negative.
There was another bug that meant it ignored all error codes from
request_irq() except -EBUSY, so it would 'succeed' despite this
(possibly causing conflicts with other ISA devices). This was fixed
by ab08999d6029bb2c79c16be5405d63d2bedbdfea 'WARNING: some
request_irq() failures ignored in el2_open()', which exposed bug 1.
This patch:
1. Replaces the use of probe_irq_{on,off}() with a real interrupt handler
2. Adds a delay before checking the interrupt-seen flag
3. Disables interrupts on all failure paths
4. Distinguishes error codes from the second request_irq() call,
consistently with the first
Compile-tested only.
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
drivers/net/3c503.c | 42 ++++++++++++++++++++++++++++++------------
1 files changed, 30 insertions(+), 12 deletions(-)
diff --git a/drivers/net/3c503.c b/drivers/net/3c503.c
index 66e0323..b74a0ea 100644
--- a/drivers/net/3c503.c
+++ b/drivers/net/3c503.c
@@ -380,6 +380,12 @@ out:
return retval;
}
+static irqreturn_t el2_probe_interrupt(int irq, void *seen)
+{
+ *(bool *)seen = true;
+ return IRQ_HANDLED;
+}
+
static int
el2_open(struct net_device *dev)
{
@@ -391,23 +397,35 @@ el2_open(struct net_device *dev)
outb(EGACFR_NORM, E33G_GACFR); /* Enable RAM and interrupts. */
do {
- retval = request_irq(*irqp, NULL, 0, "bogus", dev);
- if (retval >= 0) {
+ bool seen;
+
+ retval = request_irq(*irqp, el2_probe_interrupt, 0,
+ dev->name, &seen);
+ if (retval == -EBUSY)
+ continue;
+ if (retval < 0)
+ goto err_disable;
+
/* Twinkle the interrupt, and check if it's seen. */
- unsigned long cookie = probe_irq_on();
+ seen = false;
+ smp_wmb();
outb_p(0x04 << ((*irqp == 9) ? 2 : *irqp), E33G_IDCFR);
outb_p(0x00, E33G_IDCFR);
- if (*irqp == probe_irq_off(cookie) && /* It's a good IRQ
line! */
- ((retval = request_irq(dev->irq = *irqp,
- eip_interrupt, 0,
- dev->name, dev)) == 0))
- break;
- } else {
- if (retval != -EBUSY)
- return retval;
- }
+ msleep(1);
+ free_irq(*irqp, el2_probe_interrupt);
+ if (!seen)
+ continue;
+
+ retval = request_irq(dev->irq = *irqp, eip_interrupt, 0,
+ dev->name, dev);
+ if (retval == -EBUSY)
+ continue;
+ if (retval < 0)
+ goto err_disable;
} while (*++irqp);
+
if (*irqp == 0) {
+ err_disable:
outb(EGACFR_IRQOFF, E33G_GACFR); /* disable interrupts. */
return -EAGAIN;
}
--
1.7.0.3
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