Ok, I should have caught that :-( Another question -
Now that the PROC_LOCK on p is obtained the all_proc lock is released
and the function returns, at this point can't the proc get deallocated ?
Nikhil
242 struct proc *
243 pfind(pid)
244 register pid_t pid;
245 {
246 register struct proc *p;
247
248 sx_slock(&allproc_lock);
249 LIST_FOREACH(p, PIDHASH(pid), p_hash)
250 if (p->p_pid == pid) {
251 if (p->p_state == PRS_NEW) {
252 p = NULL;
253 break;
254 }
255 PROC_LOCK(p);
256 break;
257 }
258 sx_sunlock(&allproc_lock);
259 return (p);
260 }
-----Original Message-----
From: Roman Divacky [mailto:[EMAIL PROTECTED]
Sent: Tuesday, April 01, 2008 12:56 AM
To: Rao, Nikhil
Cc: freebsd-hackers@freebsd.org
Subject: Re: pfind() and the proc structure
On Mon, Mar 31, 2008 at 11:03:31PM -0700, Rao, Nikhil wrote:
> Hi List,
>
> The pfind(..) (in kern_proc.c) function below returns the proc
structure
> for the PID passed in
>
> Say the thread that calls pfind() gets blocked at PROC_LOCK(p) (line
255
> below), in the meantime what prevents the process from exiting and
> deallocating the proc structure ? Maybe I am missing something simple
or
> the answer requires knowledge of the mutex implementation.
thats what the allproc_lock is there for
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