Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a304e1b82808904c561b7b149b467e338c53fcce
Commit:     a304e1b82808904c561b7b149b467e338c53fcce
Parent:     f9e4acf3befd3b2903e01b3ef1bd344f03299826
Author:     David Woodhouse <[EMAIL PROTECTED]>
AuthorDate: Mon Feb 12 00:52:00 2007 -0800
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon Feb 12 09:48:28 2007 -0800

    [PATCH] Debug shared irqs
    
    Drivers registering IRQ handlers with SA_SHIRQ really ought to be able to
    handle an interrupt happening before request_irq() returns.  They also
    ought to be able to handle an interrupt happening during the start of their
    call to free_irq().  Let's test that hypothesis....
    
    [EMAIL PROTECTED]: Kconfig fixes]
    Signed-off-by: David Woodhouse <[EMAIL PROTECTED]>
    Cc: Arjan van de Ven <[EMAIL PROTECTED]>
    Signed-off-by: Jesper Juhl <[EMAIL PROTECTED]>
    Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
    Signed-off-by: Adrian Bunk <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 kernel/irq/manage.c |   33 +++++++++++++++++++++++++++++++++
 lib/Kconfig.debug   |    9 +++++++++
 2 files changed, 42 insertions(+), 0 deletions(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 8b961ad..400b12a 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -357,6 +357,7 @@ void free_irq(unsigned int irq, void *dev_id)
        struct irq_desc *desc;
        struct irqaction **p;
        unsigned long flags;
+       irqreturn_t (*handler)(int, void *) = NULL;
 
        WARN_ON(in_interrupt());
        if (irq >= NR_IRQS)
@@ -396,6 +397,8 @@ void free_irq(unsigned int irq, void *dev_id)
 
                        /* Make sure it's not being used on another CPU */
                        synchronize_irq(irq);
+                       if (action->flags & IRQF_SHARED)
+                               handler = action->handler;
                        kfree(action);
                        return;
                }
@@ -403,6 +406,17 @@ void free_irq(unsigned int irq, void *dev_id)
                spin_unlock_irqrestore(&desc->lock, flags);
                return;
        }
+#ifdef CONFIG_DEBUG_SHIRQ
+       if (handler) {
+               /*
+                * It's a shared IRQ -- the driver ought to be prepared for it
+                * to happen even now it's being freed, so let's make sure....
+                * We do this after actually deregistering it, to make sure that
+                * a 'real' IRQ doesn't run in parallel with our fake
+                */
+               handler(irq, dev_id);
+       }
+#endif
 }
 EXPORT_SYMBOL(free_irq);
 
@@ -475,6 +489,25 @@ int request_irq(unsigned int irq, irq_handler_t handler,
 
        select_smp_affinity(irq);
 
+#ifdef CONFIG_DEBUG_SHIRQ
+       if (irqflags & IRQF_SHARED) {
+               /*
+                * It's a shared IRQ -- the driver ought to be prepared for it
+                * to happen immediately, so let's make sure....
+                * We do this before actually registering it, to make sure that
+                * a 'real' IRQ doesn't run in parallel with our fake
+                */
+               if (irqflags & IRQF_DISABLED) {
+                       unsigned long flags;
+
+                       local_irq_save(flags);
+                       handler(irq, dev_id);
+                       local_irq_restore(flags);
+               } else
+                       handler(irq, dev_id);
+       }
+#endif
+
        retval = setup_irq(irq, action);
        if (retval)
                kfree(action);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 356a5ab..63f04c1 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -77,6 +77,15 @@ config DEBUG_KERNEL
          Say Y here if you are developing drivers or trying to debug and
          identify kernel problems.
 
+config DEBUG_SHIRQ
+       bool "Debug shared IRQ handlers"
+       depends on DEBUG_KERNEL && GENERIC_HARDIRQS
+       help
+         Enable this to generate a spurious interrupt as soon as a shared
+         interrupt handler is registered, and just before one is deregistered.
+         Drivers ought to be able to handle interrupts coming in at those
+         points; some don't and need to be caught.
+
 config LOG_BUF_SHIFT
        int "Kernel log buffer size (16 => 64KB, 17 => 128KB)" if DEBUG_KERNEL
        range 12 21
-
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