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Wysocki" , Viresh Kumar , Wyes Karny , Perry Yuan , Mario Limonciello Cc: Arnd Bergmann , Perry Yuan , Mario Limonciello , Jinzhou Su , Meng Li , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use Date: Tue, 7 Feb 2023 17:12:51 +0100 Message-Id: <20230207161256.271613-1-arnd@kernel.org> X-Mailer: git-send-email 2.39.1 MIME-Version: 1.0 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1757189561683356760?= X-GMAIL-MSGID: =?utf-8?q?1757189561683356760?= From: Arnd Bergmann The new epp support causes warnings about three separate but related bugs: 1) failing before allocation should just return an error: drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized] if (!dev) ^~~~ drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here return ret; ^~~ 2) wrong variable to store return code: drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized] if (rc) ^~ drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here return ret; ^~~ drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is always false if (rc) ^~~~~~~ 3) calling amd_pstate_set_epp() in cleanup path after determining that it should not be called: drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized] if (cpudata->epp_policy == cpudata->policy) ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here amd_pstate_set_epp(cpudata, epp); ^~~ All three are trivial to fix, but most likely there are additional bugs in this function when the error handling was not really tested. Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors") Signed-off-by: Arnd Bergmann Tested-by: Wyes Karny Reviewed-by: Yuan Perry Acked-by: Huang Rui --- drivers/cpufreq/amd-pstate.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index 168a28bed6ee..847f5f31396d 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy) int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret; struct amd_cpudata *cpudata; struct device *dev; - int rc; u64 value; /* @@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy) amd_perf_ctl_reset(policy->cpu); dev = get_cpu_device(policy->cpu); if (!dev) - goto free_cpudata1; + return -ENODEV; cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL); if (!cpudata) @@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy) cpudata->cpu = policy->cpu; cpudata->epp_policy = 0; - rc = amd_pstate_init_perf(cpudata); - if (rc) + ret = amd_pstate_init_perf(cpudata); + if (ret) goto free_cpudata1; min_freq = amd_get_min_freq(cpudata); @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu) value |= (u64)epp << 24; } + amd_pstate_set_epp(cpudata, epp); skip_epp: WRITE_ONCE(cpudata->cppc_req_cached, value); - amd_pstate_set_epp(cpudata, epp); cpufreq_cpu_put(policy); }