From: Venki Pallipadi <venkatesh.pallipadi@intel.com>
Date: Mon, 26 Mar 2007 19:03:19 +0000 (-0700)
Subject: [PATCH] Fix maxcpus=1 trigerring BUG() in cpufreq
X-Git-Tag: v2.6.21-rc6~113
X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=ec28297a562f2b022115b9eb82e4ea724d996240;p=~emulex%2Finfiniband.git

[PATCH] Fix maxcpus=1 trigerring BUG() in cpufreq

Ingo reported it on lkml in the thread
  "2.6.21-rc5: maxcpus=1 crash in cpufreq: kernel BUG at drivers/cpufreq/cpufreq.c:82!"

This check added to remove_dev  is symmetric to one in add_dev and handles
callbacks for offline cpus cleanly.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index f52facc570f..3162010900c 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1015,6 +1015,10 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
 {
 	unsigned int cpu = sys_dev->id;
 	int retval;
+
+	if (cpu_is_offline(cpu))
+		return 0;
+
 	if (unlikely(lock_policy_rwsem_write(cpu)))
 		BUG();