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| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2017-06-05 14:51:18 +0200 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2017-06-05 14:51:18 +0200 |
| commit | 57caf4ec2b8bfbcb4f738ab5a12eedf3a8786045 (patch) | |
| tree | 19d5662b5b54fe439eeb62520f021ff71eabf30d /drivers/cpufreq/intel_pstate.c | |
| parent | 33fc30b470983e5b641a16cccc882f6777dd50ef (diff) | |
| download | lwn-57caf4ec2b8bfbcb4f738ab5a12eedf3a8786045.tar.gz lwn-57caf4ec2b8bfbcb4f738ab5a12eedf3a8786045.zip | |
cpufreq: intel_pstate: Avoid division by 0 in min_perf_pct_min()
Commit c5a2ee7dde89 (cpufreq: intel_pstate: Active mode P-state
limits rework) incorrectly assumed that pstate.turbo_pstate would
always be nonzero for CPU0 in min_perf_pct_min() if
cpufreq_register_driver() had succeeded which may not be the case
in virtualized environments.
If that assumption doesn't hold, it leads to an early crash on boot
in intel_pstate_register_driver(), so add a sanity check to
min_perf_pct_min() to prevent the crash from happening.
Fixes: c5a2ee7dde89 (cpufreq: intel_pstate: Active mode P-state limits rework)
Reported-and-tested-by: Jongman Heo <jongman.heo@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/intel_pstate.c')
| -rw-r--r-- | drivers/cpufreq/intel_pstate.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index b7de5bd76a31..eb1158532de3 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -571,9 +571,10 @@ static inline void update_turbo_state(void) static int min_perf_pct_min(void) { struct cpudata *cpu = all_cpu_data[0]; + int turbo_pstate = cpu->pstate.turbo_pstate; - return DIV_ROUND_UP(cpu->pstate.min_pstate * 100, - cpu->pstate.turbo_pstate); + return turbo_pstate ? + DIV_ROUND_UP(cpu->pstate.min_pstate * 100, turbo_pstate) : 0; } static s16 intel_pstate_get_epb(struct cpudata *cpu_data) |