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Subject[RFC+PATCH] calling request_irq() with lock held (+sungem fix)
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Hrm.. old problem: request_irq() called with a lock held.

This is unclear wether this should be safe or not, I now IDE used to
do that, but the current implementation of request_irq() on most archs
is definitely not safe to be called in a non-sleeping context.

i386 was sort-fixed by using GFP_ATOMIC in the kmalloc() done inside
request_irq() itself, but what about all of the proc related stuff
that gets done when setup_irq() calls register_irq_proc() ? So the
_fact_ is that the current implementations in archs, including i386,
are unsafe to call from "atomic" context.

David: this patch fixes sungem for that.

Cheers,
Ben.

diff -urN linux-2.5/drivers/net/sungem.c linuxppc-2.5-benh/drivers/net/sungem.c
--- linux-2.5/drivers/net/sungem.c 2003-07-29 08:50:59.000000000 -0400
+++ linuxppc-2.5-benh/drivers/net/sungem.c 2003-07-30 13:25:32.000000000 -0400
@@ -2101,17 +2101,14 @@
gp->hw_running = 1;
}

- spin_lock_irq(&gp->lock);
-
/* We can now request the interrupt as we know it's masked
* on the controller
*/
if (request_irq(gp->pdev->irq, gem_interrupt,
SA_SHIRQ, dev->name, (void *)dev)) {
- spin_unlock_irq(&gp->lock);
-
printk(KERN_ERR "%s: failed to request irq !\n", gp->dev->name);

+ spin_lock_irq(&gp->lock);
#ifdef CONFIG_PPC_PMAC
if (!hw_was_up && gp->pdev->vendor == PCI_VENDOR_ID_APPLE)
gem_apple_powerdown(gp);
@@ -2120,10 +2117,13 @@
gp->pm_timer.expires = jiffies + 10*HZ;
add_timer(&gp->pm_timer);
up(&gp->pm_sem);
+ spin_unlock_irq(&gp->lock);

return -EAGAIN;
}

+ spin_lock_irq(&gp->lock);
+
/* Allocate & setup ring buffers */
gem_init_rings(gp);

-
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