From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Hunt, David" Subject: Re: [PATCH 1/2] power: switching to unbuffered stdio for /sys file access Date: Wed, 18 Oct 2017 11:33:56 +0100 Message-ID: <9041e0ef-2ec7-a448-0676-71c4b59b67c0@intel.com> References: <1508161628-4265-1-git-send-email-radoslaw.biernacki@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: stable@dpdk.org, alan.carew@intel.com, pablo.de.lara.guarch@intel.com To: Radoslaw Biernacki , dev@dpdk.org Return-path: In-Reply-To: <1508161628-4265-1-git-send-email-radoslaw.biernacki@linaro.org> Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi Radoslaw, On 16/10/2017 2:47 PM, Radoslaw Biernacki wrote: > This patch fixes the bug caused by improper use of buffered > stdio file access for switching the CPU frequency and > governor. Each write operation when using buffered stdio > must be flushed out and the return code from fflush() must > be verified. In buffered mode, write() syscall return value > is is not returned by fwrite()/fputs()/fprintf(). > Since with buffered approatch, fflush() need to be done > every time it is better to use unbuffered mode or not use > stdio at all (instead use plain open/write functions). To > minimize amount of changes this fix use first approach. > > Signed-off-by: Radoslaw Biernacki > --- > lib/librte_power/rte_power_acpi_cpufreq.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/lib/librte_power/rte_power_acpi_cpufreq.c b/lib/librte_power/rte_power_acpi_cpufreq.c > index 01ac5ac..8bf5685 100644 > --- a/lib/librte_power/rte_power_acpi_cpufreq.c > +++ b/lib/librte_power/rte_power_acpi_cpufreq.c > @@ -143,12 +143,13 @@ set_freq_internal(struct rte_power_info *pi, uint32_t idx) > "for setting frequency for lcore %u\n", pi->lcore_id); > return -1; > } > + /* we use unbuffered mode so following will fail if kernel will refuse > + * freq setting */ Also, there's an issue with checkpatch on the comment here. Please make sure to run your patches through checkpatch. Typically a recent version of checkpatch should be used (4.1x). Rgds, Dave. ---snip---