linux-kernel - [RESEND PATCH] genirq: warn about IRQF_SHARED|IRQF

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Date:	Tue, 12 Jan 2010 16:42:02 +0100
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	linux-kernel@...r.kernel.org
Cc:	David Brownell <dbrownell@...rs.sourceforge.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>, Nicolas Pitre <nico@...vell.com>,
	Eric Miao <eric.y.miao@...il.com>,
	John Stultz <johnstul@...ibm.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Remy Bohmer <linux@...mer.net>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	Andrea Gallo <andrea.gallo@...ricsson.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jamie Lokier <jamie@...reable.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: [RESEND PATCH] genirq: warn about IRQF_SHARED|IRQF_DISABLED at the right place

For shared irqs IRQF_DISABLED is only guaranteed for the first handler.
So only warn starting at the second registration.

The warning is moved to __setup_irq having the additional benefit of
catching actions registered using setup_irq not only register_irq.

This doesn't fix the cases where setup order is wrong but it should
report the broken cases more reliably.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc: David Brownell <dbrownell@...rs.sourceforge.net>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Nicolas Pitre <nico@...vell.com>
Cc: Eric Miao <eric.y.miao@...il.com>
Cc: John Stultz <johnstul@...ibm.com>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Remy Bohmer <linux@...mer.net>
Cc: Hugh Dickins <hugh.dickins@...cali.co.uk>
Cc: Andrea Gallo <andrea.gallo@...ricsson.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Jamie Lokier <jamie@...reable.org>
Cc: linux-arm-kernel@...ts.infradead.org
---
Hello,

until Thomas or Peter get round to dump IRQF_DISABLED completely this
patch removes some false positive warnings and adds a valid warning in
some situations that weren't catched before.

Best regards
Uwe

 kernel/irq/manage.c |   23 ++++++++++-------------
 1 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index bde4c66..d8f7415 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -702,6 +702,16 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 			goto mismatch;
 #endif
 
+		/*
+		 * handle_IRQ_event() only honors IRQF_DISABLED for the _first_
+		 * irqaction.  As the first handler might reenable irqs all bets
+		 * are off for the later handlers even if the first one has
+		 * IRQF_DISABLED, too.
+		 */
+		if (new->flags & IRQF_DISABLED)
+			pr_warning("IRQ %d/%s: IRQF_DISABLED is not guaranteed "
+					"on shared IRQs\n", irq, new->name);
+
 		/* add new interrupt at end of irq queue */
 		do {
 			old_ptr = &old->next;
@@ -1008,19 +1018,6 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
 	struct irq_desc *desc;
 	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:
-- 
1.6.6

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