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- Use _PHOLD and move it before a PROC_UNLOCK to reduce the number of

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mutex operations in kthread_create().
- Lock a kthread's proc before changing its parent via proc_reparent().
- Test P_KTHREAD not P_SYSTEM in kthread_suspend() and kthread_resume().
  P_SYSTEM just means that the process shouldn't be swapped and is used
  for vinum's daemon for example.
- Lock all the signal state used for suspending and resuming kthreads with
  the proc lock.
This commit is contained in:
John Baldwin 2001-03-07 02:36:47 +00:00
parent 57934cd3c8
commit 6451855f6d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=73911
1 changed files with 18 additions and 7 deletions
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25
sys/kern/kern_kthread.c
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@ -91,8 +91,8 @@ kthread_create(void (*func)(void *), void *arg,
PROC_LOCK(p2);
p2->p_flag |= P_SYSTEM | P_KTHREAD;
p2->p_procsig->ps_flag |= PS_NOCLDWAIT;
_PHOLD(p2);
PROC_UNLOCK(p2);
PHOLD(p2);
/* set up arg0 for 'ps', et al */
va_start(ap, fmt);
@ -119,7 +119,9 @@ kthread_exit(int ecode)
{
PROCTREE_LOCK(PT_EXCLUSIVE);
PROC_LOCK(curproc);
proc_reparent(curproc, initproc);
PROC_UNLOCK(curproc);
PROCTREE_LOCK(PT_RELEASE);
exit1(curproc, W_EXITCODE(ecode, 0));
}
@ -135,10 +137,13 @@ kthread_suspend(struct proc *p, int timo)
* Make sure this is indeed a system process and we can safely
* use the p_siglist field.
*/
if ((p->p_flag & P_SYSTEM) == 0)
PROC_LOCK(p);
if ((p->p_flag & P_KTHREAD) == 0) {
PROC_UNLOCK(p);
return (EINVAL);
}
SIGADDSET(p->p_siglist, SIGSTOP);
return tsleep((caddr_t)&p->p_siglist, PPAUSE, "suspkt", timo);
return msleep(&p->p_siglist, &p->p_mtx, PPAUSE | PDROP, "suspkt", timo);
}
int
@ -148,18 +153,24 @@ kthread_resume(struct proc *p)
* Make sure this is indeed a system process and we can safely
* use the p_siglist field.
*/
if ((p->p_flag & P_SYSTEM) == 0)
PROC_LOCK(p);
if ((p->p_flag & P_KTHREAD) == 0) {
PROC_UNLOCK(p);
return (EINVAL);
}
SIGDELSET(p->p_siglist, SIGSTOP);
wakeup((caddr_t)&p->p_siglist);
PROC_UNLOCK(p);
wakeup(&p->p_siglist);
return (0);
}
void
kthread_suspend_check(struct proc *p)
{
PROC_LOCK(p);
while (SIGISMEMBER(p->p_siglist, SIGSTOP)) {
wakeup((caddr_t)&p->p_siglist);
tsleep((caddr_t)&p->p_siglist, PPAUSE, "ktsusp", 0);
wakeup(&p->p_siglist);
msleep(&p->p_siglist, &p->p_mtx, PPAUSE, "ktsusp", 0);
}
PROC_UNLOCK(p);
}