From: Colin King <colin.king@canonical.com>
To: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
Viresh Kumar <viresh.kumar@linaro.org>,
Stephen Warren <swarren@nvidia.com>,
linux-pm@vger.kernel.org
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH][V3] cpufreq: powernow-k8: pass policy rather than use cpufreq_cpu_get
Date: Tue, 5 Jan 2021 10:19:57 +0000 [thread overview]
Message-ID: <20210105101957.59072-1-colin.king@canonical.com> (raw)
From: Colin Ian King <colin.king@canonical.com>
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()")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
V2: pass the policy to transition_frequency_fidvid rather than add
a null pointer check on the return from a cpufreq_cpu_get call.
V3: update subject line to match the fix
---
drivers/cpufreq/powernow-k8.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 0acc9e241cd7..b9ccb6a3dad9 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -878,9 +878,9 @@ static int get_transition_latency(struct powernow_k8_data *data)
/* 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(struct powernow_k8_data *data,
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 *arg)
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");
--
2.29.2
next reply other threads:[~2021-01-05 10:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-05 10:19 Colin King [this message]
2021-01-05 10:21 ` [PATCH][V3] cpufreq: powernow-k8: pass policy rather than use cpufreq_cpu_get Viresh Kumar
2021-01-07 16:39 ` Rafael J. Wysocki
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