Patch from James Harper <james.harper@bigpond.com>
I propose the attached patch to arch/i386/kernel/irq.c. it corrects what i
see as a bug in interrupt handling.
currently if a driver requests SA_INTERRUPT in an interrupt handler, it is
only called with interrupts disabled if it is the first handler in the list.
my patch modifies setup_irq to put any interrupt with SA_INTERRUPT in the
front of the handler queue (eg before any handlers without the flag).
and also modifies handle_IRQ_event to only enable interrupts when it hits the
first handler with SA_INTERRUPT not set.
the patch is against 2.5.62 and greatly improves stability on my SMP system.
arch/i386/kernel/irq.c | 51 ++++++++++++++++++++++++++++++++-----------------
1 files changed, 34 insertions(+), 17 deletions(-)
diff -puN arch/i386/kernel/irq.c~irq-sharing-fix arch/i386/kernel/irq.c
--- 25/arch/i386/kernel/irq.c~irq-sharing-fix 2003-02-24 23:31:35.000000000 -0800
+++ 25-akpm/arch/i386/kernel/irq.c 2003-02-24 23:31:35.000000000 -0800
@@ -207,11 +207,13 @@ inline void synchronize_irq(unsigned int
int handle_IRQ_event(unsigned int irq, struct pt_regs * regs, struct irqaction * action)
{
int status = 1; /* Force the "do bottom halves" bit */
-
- if (!(action->flags & SA_INTERRUPT))
- local_irq_enable();
+ int enabled = SA_INTERRUPT;
do {
+ if (~action->flags & enabled) {
+ local_irq_enable();
+ enabled = 0;
+ }
status |= action->flags;
action->handler(irq, action->dev_id, regs);
action = action->next;
@@ -770,24 +772,39 @@ int setup_irq(unsigned int irq, struct i
* The following block of code has to be executed atomically
*/
spin_lock_irqsave(&desc->lock,flags);
- p = &desc->action;
- if ((old = *p) != NULL) {
- /* Can't share interrupts unless both agree to */
- if (!(old->flags & new->flags & SA_SHIRQ)) {
- spin_unlock_irqrestore(&desc->lock,flags);
- return -EBUSY;
+ if (new->flags & SA_INTERRUPT) {
+ p = &desc->action;
+ old = *p;
+ /* Add SA_INTERRUPT interrupts to the front of the queue
+ * 'cos it's faster than adding them in the middle */
+ if (old) {
+ if (!(old->flags & new->flags & SA_SHIRQ)) {
+ spin_unlock_irqrestore(&desc->lock,flags);
+ return -EBUSY;
+ }
+ new->next = old;
+ shared = 1;
}
+ *p = new;
+ } else {
+ p = &desc->action;
+ if ((old = *p) != NULL) {
+ /* Can't share interrupts unless both agree to */
+ if (!(old->flags & new->flags & SA_SHIRQ)) {
+ spin_unlock_irqrestore(&desc->lock,flags);
+ return -EBUSY;
+ }
- /* add new interrupt at end of irq queue */
- do {
- p = &old->next;
- old = *p;
- } while (old);
- shared = 1;
+ /* add new interrupt at end of irq queue */
+ do {
+ p = &old->next;
+ old = *p;
+ } while (old);
+ shared = 1;
+ }
+ *p = new;
}
- *p = new;
-
if (!shared) {
desc->depth = 0;
desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | IRQ_WAITING | IRQ_INPROGRESS);
_