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Subject: ping//Re: [PATCH -next 2/2] selftests: Fix fscanf warning
To:     <pbonzini@redhat.com>, <shuah@kernel.org>, <bgardon@google.com>,
        <wangyanan55@huawei.com>, <axelrasmussen@google.com>,
        <drjones@redhat.com>, <seanjc@google.com>, <vkuznets@redhat.com>,
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        <yangyingliang@huawei.com>, <kvm@vger.kernel.org>,
        <linux-kselftest@vger.kernel.org>, <linux-kernel@vger.kernel.org>
References: <20210709063741.355325-1-chenlifu@huawei.com>
 <20210709063741.355325-2-chenlifu@huawei.com>
From:   chenlifu <chenlifu@huawei.com>
Message-ID: <fc55348e-566e-4684-0861-fa86a32c36f7@huawei.com>
Date:   Fri, 13 Aug 2021 15:27:32 +0800
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在 2021/7/9 14:37, Chen Lifu 写道:
> Compile selftests occurs the following warnings:
> make -C tools/testing/selftests
> ...
> 
> lib/test_util.c: In function ‘get_trans_hugepagesz’:
> lib/test_util.c:138:2: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result]
>    138 |  fscanf(f, "%ld", &size);
>        |  ^~~~~~~~~~~~~~~~~~~~~~~
> x86_64/mmio_warning_test.c: In function ‘get_warnings_count’:
> x86_64/mmio_warning_test.c:85:2: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result]
>     85 |  fscanf(f, "%d", &warnings);
>        |  ^~~~~~~~~~~~~~~~~~~~~~~~~~
> x86_64/xen_shinfo_test.c: In function ‘get_run_delay’:
> x86_64/xen_shinfo_test.c:109:9: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result]
>    109 |         fscanf(fp, "%ld %ld ", &val[0], &val[1]);
>        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> steal_time.c: In function ‘get_run_delay’:
> steal_time.c:228:2: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result]
>    228 |  fscanf(fp, "%ld %ld ", &val[0], &val[1]);
>        |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Check the return value of ‘fscanf’ to fix it.
> 
> Signed-off-by: Chen Lifu <chenlifu@huawei.com>
> ---
>   tools/testing/selftests/kvm/lib/test_util.c            | 3 ++-
>   tools/testing/selftests/kvm/steal_time.c               | 3 ++-
>   tools/testing/selftests/kvm/x86_64/mmio_warning_test.c | 3 ++-
>   tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c   | 3 ++-
>   4 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
> index af1031fed97f..02ed0d5c3aa5 100644
> --- a/tools/testing/selftests/kvm/lib/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/test_util.c
> @@ -135,7 +135,8 @@ size_t get_trans_hugepagesz(void)
>   	f = fopen("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size", "r");
>   	TEST_ASSERT(f != NULL, "Error in opening transparent_hugepage/hpage_pmd_size");
>   
> -	fscanf(f, "%ld", &size);
> +	if (fscanf(f, "%ld", &size) != 1)
> +		size = 0;
>   	fclose(f);
>   
>   	return size;
> diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
> index b0031f2d38fd..18f231c45a12 100644
> --- a/tools/testing/selftests/kvm/steal_time.c
> +++ b/tools/testing/selftests/kvm/steal_time.c
> @@ -225,7 +225,8 @@ static long get_run_delay(void)
>   
>   	sprintf(path, "/proc/%ld/schedstat", syscall(SYS_gettid));
>   	fp = fopen(path, "r");
> -	fscanf(fp, "%ld %ld ", &val[0], &val[1]);
> +	if (fscanf(fp, "%ld %ld ", &val[0], &val[1]) != 2)
> +		val[1] = 0;
>   	fclose(fp);
>   
>   	return val[1];
> diff --git a/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c b/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c
> index e6480fd5c4bd..e770037e5cc9 100644
> --- a/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c
> @@ -82,7 +82,8 @@ int get_warnings_count(void)
>   	FILE *f;
>   
>   	f = popen("dmesg | grep \"WARNING:\" | wc -l", "r");
> -	fscanf(f, "%d", &warnings);
> +	if (fscanf(f, "%d", &warnings) != 1)
> +		warnings = 0;
>   	fclose(f);
>   
>   	return warnings;
> diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
> index 117bf49a3d79..6efda86083f1 100644
> --- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
> @@ -106,7 +106,8 @@ static long get_run_delay(void)
>   
>           sprintf(path, "/proc/%ld/schedstat", syscall(SYS_gettid));
>           fp = fopen(path, "r");
> -        fscanf(fp, "%ld %ld ", &val[0], &val[1]);
> +	if (fscanf(fp, "%ld %ld ", &val[0], &val[1]) != 2)
> +		val[1] = 0;
>           fclose(fp);
>   
>           return val[1];
>