Messages in this thread | | | Subject | Re: [PATCH -next] cpufreq: Fix reserved space in cpufreq_show_cpus() | From | "yiyang (D)" <> | Date | Sat, 18 Jun 2022 18:32:16 +0800 |
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On 2022/6/15 12:56, Viresh Kumar wrote: > On 14-06-22, 15:48, Rafael J. Wysocki wrote: >> On Tue, Jun 14, 2022 at 3:37 PM Rafael J. Wysocki <rafael@kernel.org> wrote: >>> >>> On Tue, May 24, 2022 at 9:10 AM Viresh Kumar <viresh.kumar@linaro.org> wrote: >>>> >>>> On 21-05-22, 14:35, Yi Yang wrote: >>>>> Function scnprintf() would reserve space for the trailing '\0' and return >>>>> value is the number of characters written into buf not including the >>>>> trailing '\0'. internally meaning the next scnprintf() would write begin >>>>> the trailing '\0'. The code specifying "PAGE_SIZE - i - 2" here is trying >>>>> to reserve space for "\n\0" which would cause scnprintf() to reserve an >>>>> additional byte making the tail of the buf looks like this: "\n\0\0". >>>>> Thus. we should reserve only the space for one '\0'. passing in >>>>> "PAGE_SIZE - i - 1". >>>>> >>>>> Additionally, each iteration would replace the trailing '\0' from the last >>>>> iteration with a space, and append 4 additional bytes to the string making >>>>> it a total of 5 additional bytes. That means we should stop printing into >>>>> the buffer if the remaining size is less than 7 bytes(1 for the ' ', 4 for >>>>> the %u and 2 for the tailing "\n\0") >>>>> >>>>> Signed-off-by: Yi Yang <yiyang13@huawei.com> >>>>> --- >>>>> drivers/cpufreq/cpufreq.c | 6 +++--- >>>>> 1 file changed, 3 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c >>>>> index 1f6667ce43bd..60c005c9961e 100644 >>>>> --- a/drivers/cpufreq/cpufreq.c >>>>> +++ b/drivers/cpufreq/cpufreq.c >>>>> @@ -844,9 +844,9 @@ ssize_t cpufreq_show_cpus(const struct cpumask *mask, char *buf) >>>>> >>>>> for_each_cpu(cpu, mask) { >>>>> if (i) >>>>> - i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), " "); >>>>> - i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), "%u", cpu); >>>>> - if (i >= (PAGE_SIZE - 5)) >>>>> + i += scnprintf(&buf[i], (PAGE_SIZE - i - 1), " "); >>>>> + i += scnprintf(&buf[i], (PAGE_SIZE - i - 1), "%u", cpu); >>>>> + if (i >= (PAGE_SIZE - 6)) >>>>> break; >>>>> } >>>>> i += sprintf(&buf[i], "\n"); >>>> >>>> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> >>> >>> Applied as 5.20 material, thanks! >> >> And dropped, because it has been superseded by this one: >> >> https://patchwork.kernel.org/project/linux-pm/patch/b9fa08171c09343ace94a7343553a4bee4695c90.1653565641.git.viresh.kumar@linaro.org/ > > The $Subject patch is still required AFAICT, it is fixing a different problem. > Though it needs to be rebased on top of your branch now. >
What can i do for this patch?
-- Yi
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