linux-kernel - [PATCH] perfctr_watchdog: do not BUG

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Message-ID: <20070727124934.GD9828@frankl.hpl.hp.com>
Date:	Fri, 27 Jul 2007 05:49:34 -0700
From:	Stephane Eranian <eranian@....hp.com>
To:	linux-kernel@...r.kernel.org
Cc:	ak@...e.de, akpm@...ux-foundation.org,
	Stephane Eranian <eranian@....hp.com>, B.Steinbrink@....de
Subject: [PATCH] perfctr_watchdog: do not BUG_ON() when MSR is unknown

Hi,

Here is a small patch to change the behavior of the PMU msr allocator
to avoid BUG_ON() when the MSR is unknwon. Instead, it now returns
ok, which means "I do not manage". The current allocator is not
yet managing the full set of PMU registers (e.g., GLOBAL_* on Core 2).


    [watchdog] do not BUG_ON() in the MSR allocator if MSR is unknown, return ok instead
    
    signed-off-by: Stephane Eranian <eranian@....hp.com>

diff --git a/arch/i386/kernel/cpu/perfctr-watchdog.c b/arch/i386/kernel/cpu/perfctr-watchdog.c
index 4be488e..9b5d6af 100644
--- a/arch/i386/kernel/cpu/perfctr-watchdog.c
+++ b/arch/i386/kernel/cpu/perfctr-watchdog.c
@@ -120,7 +120,9 @@ int reserve_perfctr_nmi(unsigned int msr)
 	unsigned int counter;
 
 	counter = nmi_perfctr_msr_to_bit(msr);
-	BUG_ON(counter > NMI_MAX_COUNTER_BITS);
+	/* register not managed by the allocator? */
+	if (counter > NMI_MAX_COUNTER_BITS)
+		return 1;
 
 	if (!test_and_set_bit(counter, perfctr_nmi_owner))
 		return 1;
@@ -132,7 +134,9 @@ void release_perfctr_nmi(unsigned int msr)
 	unsigned int counter;
 
 	counter = nmi_perfctr_msr_to_bit(msr);
-	BUG_ON(counter > NMI_MAX_COUNTER_BITS);
+	/* register not managed by the allocator? */
+	if (counter > NMI_MAX_COUNTER_BITS)
+		return;
 
 	clear_bit(counter, perfctr_nmi_owner);
 }
@@ -142,7 +146,9 @@ int reserve_evntsel_nmi(unsigned int msr)
 	unsigned int counter;
 
 	counter = nmi_evntsel_msr_to_bit(msr);
-	BUG_ON(counter > NMI_MAX_COUNTER_BITS);
+	/* register not managed by the allocator? */
+	if (counter > NMI_MAX_COUNTER_BITS)
+		return 1;
 
 	if (!test_and_set_bit(counter, evntsel_nmi_owner))
 		return 1;
@@ -154,7 +160,9 @@ void release_evntsel_nmi(unsigned int msr)
 	unsigned int counter;
 
 	counter = nmi_evntsel_msr_to_bit(msr);
-	BUG_ON(counter > NMI_MAX_COUNTER_BITS);
+	/* register not managed by the allocator? */
+	if (counter > NMI_MAX_COUNTER_BITS)
+		return;
 
 	clear_bit(counter, evntsel_nmi_owner);
 }
-
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