From: Viresh Kumar <viresh.kumar@linaro.org>
To: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
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()
Date: Mon, 12 Feb 2018 15:59:00 +0530 [thread overview]
Message-ID: <20180212102900.GU28462@vireshk-i7> (raw)
In-Reply-To: <1518430876-24464-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com>
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 <shilpa.bhat@linux.vnet.ibm.com>
> ---
> 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
next prev parent reply other threads:[~2018-02-12 10:29 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-12 10:21 [PATCH] cpufreq: powernv: Check negative value returned by cpufreq_table_find_index_dl() Shilpasri G Bhat
2018-02-12 10:29 ` Viresh Kumar [this message]
2018-02-12 10:33 ` Shilpasri G Bhat
2018-02-12 10:40 ` Viresh Kumar
2018-02-26 9:48 ` Rafael J. Wysocki
2018-02-21 5:39 ` Michael Ellerman
2018-02-21 5:54 ` Viresh Kumar
2018-02-21 9:27 ` Rafael J. Wysocki
2018-02-21 10:02 ` Viresh Kumar
2018-02-21 10:17 ` Rafael J. Wysocki
2018-02-21 10:19 ` Viresh Kumar
2018-02-21 13:13 ` Michael Ellerman
2018-02-21 13:25 ` Rafael J. Wysocki
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