[CRIU] [PATCH] parasite-syscall: describe task's state on trap failure

[Andrew Vagin]

Acked-by: Andrew Vagin <avagin at virtuozzo.com>

On Thu, Jun 09, 2016 at 02:56:50PM +0300, Dmitry Safonov wrote:
> I think we can improve error messages to distinguish task's kills
> from segfaults from ptrace failures & etc.
> 
> Signed-off-by: Dmitry Safonov <dsafonov at virtuozzo.com>
> ---
>  criu/parasite-syscall.c | 28 ++++++++++++++++++++++------
>  1 file changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/criu/parasite-syscall.c b/criu/parasite-syscall.c
> index f9e0bac7ffbf..e8e31fb2da4a 100644
> --- a/criu/parasite-syscall.c
> +++ b/criu/parasite-syscall.c
> @@ -934,6 +934,26 @@ static int parasite_fini_seized(struct parasite_ctl *ctl)
>  	return 0;
>  }
>  
> +static bool task_is_trapped(int status, pid_t pid)
> +{
> +	if (WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP)
> +		return true;
> +
> +	pr_err("Task %d is in unexpected state: %x\n", pid, status);
> +	if (WIFEXITED(status))
> +		pr_err("Task exited with %d\n", WEXITSTATUS(status));
> +	if (WIFSIGNALED(status))
> +		pr_err("Task signaled with %d: %s\n",
> +			WTERMSIG(status), strsignal(WTERMSIG(status)));
> +	if (WIFSTOPPED(status))
> +		pr_err("Task stopped with %d: %s\n",
> +			WSTOPSIG(status), strsignal(WSTOPSIG(status)));
> +	if (WIFCONTINUED(status))
> +		pr_err("Task continued\n");
> +
> +	return false;
> +}
> +
>  /*
>   * Trap tasks on the exit from the specified syscall
>   *
> @@ -957,10 +977,8 @@ int parasite_stop_on_syscall(int tasks, const int sys_nr, enum trace_flags trace
>  			return -1;
>  		}
>  
> -		if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGTRAP) {
> -			pr_err("Task is in unexpected state: %x\n", status);
> +		if (!task_is_trapped(status, pid))
>  			return -1;
> -		}
>  
>  		pr_debug("%d was trapped\n", pid);
>  
> @@ -996,10 +1014,8 @@ int parasite_stop_on_syscall(int tasks, const int sys_nr, enum trace_flags trace
>  				return -1;
>  			}
>  
> -			if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGTRAP) {
> -				pr_err("Task is in unexpected state: %x\n", status);
> +			if (!task_is_trapped(status, pid))
>  				return -1;
> -			}
>  
>  			pr_debug("%d was stopped\n", pid);
>  			tasks--;
> -- 
> 2.8.3
> 
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