On Thu, Nov 03, 2005 at 11:02:01PM -0600, Mike Gerdts wrote:
> - As the process is exiting (wow, exiting is a lot of work!) it adds
> its children's usr and sys time to its own usr and sys time.
>
> http://cvs.opensolaris.org/source/xref/on/usr/src/uts/common/os/exit.c#1172
>
> 1124 void
> 1125 freeproc(proc_t *p)
> 1126 {
> ...
> 1172 p->p_nextofkin->p_cutime += p->p_utime;
> 1173 p->p_nextofkin->p_cstime += p->p_stime;
>
> - The sums calculated above are propagated to the parent process.
> Kinda sad that the parent process is the "next of kin".
> - It seems as though there may be a race condition here. I'm not sure
> that the operations on lines 1172 and 1173 are protected by a lock.
> It seems as though p->p_nextofkin->p_lock should be held when
> incrementing these values in the event that multiple children are
> being reaped at the same time.
This is protected by pidlock:
void
freeproc(proc_t *p)
{
proc_t *q;
ASSERT(p->p_stat == SZOMB);
ASSERT(p->p_tlist == NULL);
ASSERT(MUTEX_HELD(&pidlock));
so only one process being processed at a time. (one of the many reasons
pidlock is hard to break up. pidlock breakup so is a reoccurring hallway
conversation 'round these parts.)
Cheers,
- jonathan
--
Jonathan Adams, Solaris Kernel Development
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