linux-kernel - Re: [PATCH v3 2/2] selftests/resctrl: Adjust SNC support messages

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Message-ID: <evds3zyrwl3tgs7l6ppcg3bnvlxaewcetacuppek4uevx5i7lb@rj7ciugpp5u3>
Date: Wed, 3 Jul 2024 08:50:27 +0200
From: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
To: "Luck, Tony" <tony.luck@...el.com>
CC: "shuah@...nel.org" <shuah@...nel.org>, "Chatre, Reinette"
	<reinette.chatre@...el.com>, "Yu, Fenghua" <fenghua.yu@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
	"ilpo.jarvinen@...ux.intel.com" <ilpo.jarvinen@...ux.intel.com>
Subject: Re: [PATCH v3 2/2] selftests/resctrl: Adjust SNC support messages

Thanks for the review,

On 2024-07-01 at 18:04:00 +0200, Luck, Tony wrote:
>+static bool cpus_offline_empty(void)
>+{
>+	char offline_cpus_str[64];
>+	FILE *fp;
>+
>+	fp = fopen("/sys/devices/system/cpu/offline", "r");
>
>Check for fp == NULL before using it.

Thanks, will add it.

>
>+	if (fscanf(fp, "%s", offline_cpus_str) < 0) {
>
>fscanf() seems like a heavy hammer.
>
>	if (fgets(offline_cpus_str, sizeof(offline_cpus_str), fp) == NULL) {
>+		if (!errno) {
>
>Don't need an errno check (seems dubious mixing errno with stdio).

fscanf() returns "-1" when nothing was read as well as if there was an error.
But when nothing was read the errno is "0" instead of some error code so I could
differentiate the cases that way. The fgetc() you settled on shouldn't have this
problem.

>
>+			fclose(fp);
>+			return 1;
>
>			return true;
>
>+		}
>+		ksft_perror("Could not read offline CPUs file!");
>+	}
>+
>+	fclose(fp);
>+
>+	return 0;
>
>	return false;
>+}
>

-- 
Kind regards
Maciej Wieczór-Retman