Messages in this thread | | | Subject | Re: [PATCH] cpufreq: powernv: Check negative value returned by cpufreq_table_find_index_dl() | From | Shilpasri G Bhat <> | Date | Mon, 12 Feb 2018 16:03:42 +0530 |
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Hi,
On 02/12/2018 03:59 PM, Viresh Kumar wrote: > 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 ?
I agree too. There is no way we can get -1 with initialized cpu frequency table. We don't initialize powernv-cpufreq if we don't have valid CPU frequency entries. Is there any other way to suppress the Coverity tool warning apart from ignoring it?
Thanks and Regards, Shilpa
> >> 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 >
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