From patchwork Tue Feb 7 16:12:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 13131832 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44147C636CC for ; Tue, 7 Feb 2023 16:13:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232248AbjBGQNF (ORCPT ); Tue, 7 Feb 2023 11:13:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232005AbjBGQND (ORCPT ); Tue, 7 Feb 2023 11:13:03 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7ED98DBEF; Tue, 7 Feb 2023 08:13:01 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id ECA1060F16; Tue, 7 Feb 2023 16:13:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A13AC433D2; Tue, 7 Feb 2023 16:12:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1675786380; bh=cC2tkzskefDBrZsRvMNSczr6SitbzsKg7wGCqoUStHs=; h=From:To:Cc:Subject:Date:From; b=f6UuGFSLOAa3/jEqTL8xCu752LB/v8U3T4/n7H7TP+DnA7MHVJ5Vo5N6wy95yp83P 3RzDdYgxP0osFCxQoOpBVQ6QBH2x9upd1ijSxseNfiXM2jyY23tInRrYN/inEEjIEG GPvz+k1Z1MlR7IVEt67M5aTJrybyZw5jDsUOkUFymVJjX/SlCwn7n24j6Vx5Dctp4F YNCXUtoEGBQ1XJt914hG+MgsBiPcZ5bSnpnmdS6Gtknc5EOYbsBxUAljNC75gS2rh8 CMmRnOw9YU/dCZC6ACchSa1JcLgx1HKsBsJwkEtVF8w3aPEVcwndJ12mLguLm7M7wO ZuWqcudZxdoyQ== From: Arnd Bergmann To: Huang Rui , "Rafael J. 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 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org 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); }