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Date: Wed, 18 Aug 2004 15:30:05 +0200
Message-ID: <s5hzn4s4lr6.wl@alsa2.suse.de>
From: Takashi Iwai <tiwai@suse.de>
To: Thomas Charbonnel <thomas@undata.org>
Cc: Ingo Molnar <mingo@elte.hu>, Lee Revell <rlrevell@joe-job.com>,
       Florian Schmidt <mista.tapas@gmx.net>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       Felipe Alfaro Solana <felipe_alfaro@linuxmail.org>
Subject: Re: [patch] voluntary-preempt-2.6.8.1-P2
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At Wed, 18 Aug 2004 14:22:07 +0200,
Thomas Charbonnel wrote:
> 
> As a side note, and this has already been reported here several times,
> the SA_INTERRUPT flag set notably by the sound card drivers handlers is
> not honored on current kernels if the device is not the first one to be
> registered. A simple fix would be to add SA_INTERRUPT handlers at the
> beginning instead of the end of the irq queue in setup_irq.
> 
> Similarly, when using SA_SAMPLE_RANDOM, all devices on the given irq
> contribute to the entropy, even those that have a predictable interrupt
> rate (e.g. sound cards), and/or for which the number of interrupts could
> outweight the number of interrupts of the original SA_SAMPLE_RANDOM
> driver. 

Hmm, something like this?


Takashi

--- linux/arch/i386/kernel/irq.c	2004-08-18 15:15:18.272067276 +0200
+++ linux/arch/i386/kernel/irq.c	2004-08-18 15:26:13.513979698 +0200
@@ -219,15 +219,22 @@ inline void synchronize_irq(unsigned int
 asmlinkage int handle_IRQ_event(unsigned int irq,
 		struct pt_regs *regs, struct irqaction *action)
 {
-	int status = 1;	/* Force the "do bottom halves" bit */
-	int retval = 0;
-
-	if (!(action->flags & SA_INTERRUPT))
+	int status;
+	int ret, retval = 0;
+	struct irqaction *ac;
+
+	status = 0;
+	for (ac = action; ac; ac = ac->next)
+		status |= ac->flags;
+	if (!(status & SA_INTERRUPT))
 		local_irq_enable();
 
+	status = 0;
 	do {
-		status |= action->flags;
-		retval |= action->handler(irq, action->dev_id, regs);
+		ret = action->handler(irq, action->dev_id, regs);
+		if (ret)
+			status |= action->flags;
+		retval |= ret;
 		action = action->next;
 	} while (action);
 	if (status & SA_SAMPLE_RANDOM)