Re: [Crash-utility] [PATCH v2 03/10] back_trace: don't check /proc if !LOCAL_ACTIVE()
On 04/28, Dave Anderson wrote:
> --- a/kernel.c
> +++ b/kernel.c
> @@ -2902,7 +2902,7 @@ back_trace(struct bt_info *bt)
>
> if (ACTIVE() && !INSTACK(esp, bt)) {
> sprintf(buf, "/proc/%ld", bt->tc->pid);
> - if (!file_exists(buf, NULL))
> + if (!(LOCAL_ACTIVE() && file_exists(buf, NULL)))
> error(INFO, "task no longer exists\n");
> else
> error(INFO,
> --
> 2.5.0
This doesn't make sense to me. If it's !LOCAL_ACTIVE() (i.e. hybrid-live-dump),
then
why would you want to call file_exists()?
It won't be called in this case, please see below.
Shouldn't it be: LOCAL_ACTIVE() and !file_exists()
This is what I did initially... then decided that error("task no longer
exists\n")
makes more sense if !LOCAL_ACTIVE() && !INSTACK(esp, bt).
IOW. with the patch above the code actually does
if (ACTIVE() && !INSTACK(...)) {
if (LOCAL_ACTIVE() && file_exists(...))
error("invalid/stale stack pointer");
else
error("task no longer exists\n");
}
is it wrong?
I thought that !INSTACK() here likely means the task has gone, but back_trace()
does the additional file_exists() to verify this, and "invalid/stale stack
pointer"
error means that something was wrong.
No?
Oleg.