linux-kernel - [PATCH][OPROFILE] x86: Use for_each_possible_cpu to allocate msrs (was [PATCH] x86: fix oprofile double free (was Re: Multiple free during oprofile unload))

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Message-ID: <20070531022427.GA21633@ghostprotocols.net>
Date:	Wed, 30 May 2007 23:24:27 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	John Levon <levon@...ementarian.org>
Cc:	linux-kernel@...r.kernel.org, chrisw@...s-sol.org,
	alan@...rguk.ukuu.org.uk, davej@...hat.com, ak@....de
Subject: [PATCH][OPROFILE] x86: Use for_each_possible_cpu to allocate msrs
	(was [PATCH] x86: fix oprofile double free (was Re: Multiple free
	during oprofile unload))

The fix for the fix needed a fix: allocate_msrs() was using
for_each_online_cpu(), but nmi_setup uses for_each_possible_cpu(), and
in my test machine, a Dell Poweredge 1950 I have 2 dual core Xeons,
which makes for 4 possible cores, but wait, they are HT capable, so...

[acme@...a linux-2.6.21.3.orig]$ dmesg | grep Allowing
SMP: Allowing 8 CPUs, 4 hotplug CPUs
[acme@...a linux-2.6.21.3.orig]$

We have 8 possible CPUs, but only 4 online, b00m. Fix it by making
allocate_msrs agree with nmi_setup, i.e. make both use
for_each_possible_cpu().

Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---


diff -uNrp linux-2.6.21.3.orig/arch/i386/oprofile/nmi_int.c linux-2.6.21.3.new/arch/i386/oprofile/nmi_int.c
--- linux-2.6.21.3.orig/arch/i386/oprofile/nmi_int.c	2007-05-30 23:08:33.000000000 -0300
+++ linux-2.6.21.3.new/arch/i386/oprofile/nmi_int.c	2007-05-30 23:09:17.000000000 -0300
@@ -154,7 +154,7 @@ static int allocate_msrs(void)
 	size_t counters_size = sizeof(struct op_msr) * model->num_counters;
 
 	int i;
-	for_each_online_cpu(i) {
+	for_each_possible_cpu(i) {
 		cpu_msrs[i].counters = kmalloc(counters_size, GFP_KERNEL);
 		if (!cpu_msrs[i].counters) {
 			success = 0;
-
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