[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>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index f52facc570f5..3162010900c9 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();