Re: [PATCH] kvm tools: Change method of retrieving process name

[Ingo Molnar <mingo@elte.hu>]

* Sasha Levin <levinsasha928@gmail.com> wrote:

> This patch changes './kvm list' to retrieve process name from
> '/proc/<pid>/stat' instead of '/proc/<pid>/comm' as it appears the latter
> does not exist by default on several systems.
> 
> Reported-by: pradeep <psuriset@linux.vnet.ibm.com>
> Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
> ---
>  tools/kvm/builtin-list.c |   21 ++++++++++++++-------
>  1 files changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/kvm/builtin-list.c b/tools/kvm/builtin-list.c
> index 2d37ecb..89a0465 100644
> --- a/tools/kvm/builtin-list.c
> +++ b/tools/kvm/builtin-list.c
> @@ -13,25 +13,32 @@
>  static void print_guest(const char *name, int pid)
>  {
>  	char proc_name[PATH_MAX];
> -	char comm[sizeof(PROCESS_NAME)];
> -	int fd;
> +	char *comm = NULL;
> +	FILE *fd;
>  
> -	sprintf(proc_name, "/proc/%d/comm", pid);
> -	fd = open(proc_name, O_RDONLY);
> -	if (fd <= 0)
> +	sprintf(proc_name, "/proc/%d/stat", pid);
> +	fd = fopen(proc_name, "r");
> +	if (fd == NULL)
>  		goto cleanup;

No, instead we should fall back to 'stat' if the 'comm' access fails. 
The 'stat' field contains a lot more data and is thus slower - while 
'comm' only outputs the comm.

Thanks,

	Ingo