The patch titled
irq: warn about (IRQF_DISABLED|IRQF_SHARED)
has been added to the -mm tree. Its filename is
irq-warn-about-irqf_disabledirqf_shared.patch
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------------------------------------------------------
Subject: irq: warn about (IRQF_DISABLED|IRQF_SHARED)
From: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
We periodically waste time tracking down problems caused by the IRQ
framework not respecting IRQF_DISABLED for some shared IRQ cases. Linus
views this as "will not fix", but we're still left with the bugs caused by
this misbehavior.
This patch adds a nag message in request_irq(), so that drivers can fix
their IRQ handlers to avoid this problem.
Note that developers will never see the relevant bugs when they run with
LOCKDEP, so it's no wonder these bugs are hard to find. (That also means
LOCKDEP is overlooking some IRQ-related bugs involving IRQ handlers that
don't set IRQF_DISABLED...)
This was the root cause of some USB oopsing a while back ...
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/irq/manage.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff -puN kernel/irq/manage.c~irq-warn-about-irqf_disabledirqf_shared kernel/irq/manage.c
--- a/kernel/irq/manage.c~irq-warn-about-irqf_disabledirqf_shared
+++ a/kernel/irq/manage.c
@@ -604,6 +604,18 @@ int request_irq(unsigned int irq, irq_ha
struct irqaction *action;
int retval;
+ /*
+ * handle_IRQ_event() always ignores IRQF_DISABLED except for
+ * the _first_ irqaction (sigh). That can cause oopsing, but
+ * the behavior is classified as "will not fix" so we need to
+ * start nudging drivers away from using that idiom.
+ */
+ if ((irqflags & (IRQF_SHARED|IRQF_DISABLED))
+ == (IRQF_SHARED|IRQF_DISABLED))
+ pr_warning("IRQ %d/%s: IRQF_DISABLED is not "
+ "guaranteed on shared IRQs\n",
+ irq, devname);
+
#ifdef CONFIG_LOCKDEP
/*
* Lockdep wants atomic interrupt handlers:
_
Patches currently in -mm which might be from dbrownell@xxxxxxxxxxxxxxxxxxxxx are
revert-rtc-cdev-lock_kernel-pushdown.patch
linux-next.patch
usb-hso-driver-fix-kconfig.patch
rtc-ds1307-alarm-support-for-ds1337-ds1339.patch
rtc-remove-some-nop-open-release-methods.patch
legacy-rtc-remove-needless-confusing-hpet_rtc_irq-option.patch
irq-warn-about-irqf_disabledirqf_shared.patch
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