From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-x241.google.com (mail-pl0-x241.google.com [IPv6:2607:f8b0:400e:c01::241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3zg22r5ZRtzF0mv for ; Mon, 12 Feb 2018 21:29:05 +1100 (AEDT) Received: by mail-pl0-x241.google.com with SMTP id 13so4835710plb.5 for ; Mon, 12 Feb 2018 02:29:05 -0800 (PST) Date: Mon, 12 Feb 2018 15:59:00 +0530 From: Viresh Kumar To: Shilpasri G Bhat Cc: rjw@rjwysocki.net, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au Subject: Re: [PATCH] cpufreq: powernv: Check negative value returned by cpufreq_table_find_index_dl() Message-ID: <20180212102900.GU28462@vireshk-i7> References: <1518430876-24464-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1518430876-24464-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 12-02-18, 15:51, Shilpasri G Bhat wrote: > This patch fixes the below Coverity warning: > > *** CID 182816: Memory - illegal accesses (NEGATIVE_RETURNS) > /drivers/cpufreq/powernv-cpufreq.c: 1008 in powernv_fast_switch() > 1002 unsigned int target_freq) > 1003 { > 1004 int index; > 1005 struct powernv_smp_call_data freq_data; > 1006 > 1007 index = cpufreq_table_find_index_dl(policy, target_freq); > >>> CID 182816: Memory - illegal accesses (NEGATIVE_RETURNS) > >>> Using variable "index" as an index to array "powernv_freqs". > 1008 freq_data.pstate_id = powernv_freqs[index].driver_data; > 1009 freq_data.gpstate_id = powernv_freqs[index].driver_data; > 1010 set_pstate(&freq_data); > 1011 > 1012 return powernv_freqs[index].frequency; > 1013 } > > Signed-off-by: Shilpasri G Bhat > --- > drivers/cpufreq/powernv-cpufreq.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c > index 29cdec1..69edfe9 100644 > --- a/drivers/cpufreq/powernv-cpufreq.c > +++ b/drivers/cpufreq/powernv-cpufreq.c > @@ -1005,6 +1005,9 @@ static unsigned int powernv_fast_switch(struct cpufreq_policy *policy, > struct powernv_smp_call_data freq_data; > > index = cpufreq_table_find_index_dl(policy, target_freq); > + if (unlikely(index < 0)) > + index = get_nominal_index(); > + AFAICT, you will get -1 here only if the freq table had no valid frequencies (or the freq table is empty). Why would that happen ? > freq_data.pstate_id = powernv_freqs[index].driver_data; > freq_data.gpstate_id = powernv_freqs[index].driver_data; > set_pstate(&freq_data); > -- > 1.8.3.1 -- viresh