[PATCH 5.10 060/103] cpufreq: powernow-k8: pass policy rather than use cpufreq_cpu_get()

Greg Kroah-Hartman
2021-01-15T12:43:53Z

From: Colin Ian King <colin.king@canonical.com>

commit 943bdd0cecad06da8392a33093230e30e501eccc upstream.

Currently there is an unlikely case where cpufreq_cpu_get() returns a
NULL policy and this will cause a NULL pointer dereference later on.

Fix this by passing the policy to transition_frequency_fidvid() from
the caller and hence eliminating the need for the cpufreq_cpu_get()
and cpufreq_cpu_put().

Thanks to Viresh Kumar for suggesting the fix.

Addresses-Coverity: ("Dereference null return")
Fixes: b43a7ffbf33b ("cpufreq: Notify all policy->cpus in cpufreq_notify_transition()")
Suggested-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/cpufreq/powernow-k8.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -878,9 +878,9 @@ static int get_transition_latency(struct

/* Take a frequency, and issue the fid/vid transition command */
static int transition_frequency_fidvid(struct powernow_k8_data *data,
- unsigned int index)
+ unsigned int index,
+ struct cpufreq_policy *policy)
{
- struct cpufreq_policy *policy;
u32 fid = 0;
u32 vid = 0;
int res;
@@ -912,9 +912,6 @@ static int transition_frequency_fidvid(s
freqs.old = find_khz_freq_from_fid(data->currfid);
freqs.new = find_khz_freq_from_fid(fid);

- policy = cpufreq_cpu_get(smp_processor_id());
- cpufreq_cpu_put(policy);
-
cpufreq_freq_transition_begin(policy, &freqs);
res = transition_fid_vid(data, fid, vid);
cpufreq_freq_transition_end(policy, &freqs, res);
@@ -969,7 +966,7 @@ static long powernowk8_target_fn(void *a

powernow_k8_acpi_pst_values(data, newstate);

- ret = transition_frequency_fidvid(data, newstate);
+ ret = transition_frequency_fidvid(data, newstate, pol);

if (ret) {
pr_err("transition frequency failed\n");