From 26d204afa18f7df177f21bdb3759e0098ca8f7d5 Mon Sep 17 00:00:00 2001 From: "Pallipadi, Venkatesh" Date: Wed, 29 Jul 2009 13:36:10 -0700 Subject: [PATCH] [CPUFREQ] Fix NULL pointer dereference regression in conservative governor Commit ee88415caf736b89500f16e0a545614541a45005 introduced this regression when it removed enable bit in cpu_dbs_info_s. That added a possibility of dbs_cpufreq_notifier getting called for a CPU that is not yet managed by conservative governor. That will happen as the transition notifier is set as soon as one CPU switches to conservative governor and other CPUs can get a NULL pointer dereference without the enable bit check. Add the enable bit back again. Reported-by: Lermytte Christophe Signed-off-by: Venkatesh Pallipadi Signed-off-by: Dave Jones --- drivers/cpufreq/cpufreq_conservative.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c index 57490502b21c..bdea7e2f94ba 100644 --- a/drivers/cpufreq/cpufreq_conservative.c +++ b/drivers/cpufreq/cpufreq_conservative.c @@ -63,6 +63,7 @@ struct cpu_dbs_info_s { unsigned int down_skip; unsigned int requested_freq; int cpu; + unsigned int enable:1; /* * percpu mutex that serializes governor limit change with * do_dbs_timer invocation. We do not want do_dbs_timer to run @@ -141,6 +142,9 @@ dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, struct cpufreq_policy *policy; + if (!this_dbs_info->enable) + return 0; + policy = this_dbs_info->cur_policy; /* @@ -497,6 +501,7 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info) int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate); delay -= jiffies % delay; + dbs_info->enable = 1; INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer); queue_delayed_work_on(dbs_info->cpu, kconservative_wq, &dbs_info->work, delay); @@ -504,6 +509,7 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info) static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info) { + dbs_info->enable = 0; cancel_delayed_work_sync(&dbs_info->work); } -- 2.20.1