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fork: remove avoidable proc lock/unlock pair

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We don't have to access the process after making it runnable, so there
is no need to hold it either.

Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Mateusz Guzik 2018-11-22 21:29:36 +00:00
parent b00b27e925
commit a5ac8272c0
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=340785
2 changed files with 7 additions and 15 deletions
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18
sys/kern/kern_fork.c
View File

@ -719,11 +719,6 @@ do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *
if ((fr->fr_flags & RFMEM) == 0 && dtrace_fasttrap_fork)
dtrace_fasttrap_fork(p1, p2);
#endif
/*
* Hold the process so that it cannot exit after we make it runnable,
* but before we wait for the debugger.
*/
_PHOLD(p2);
if (fr->fr_flags & RFPPWAIT) {
_PHOLD(p2);
td->td_pflags |= TDP_RFPPWAIT;
@ -783,8 +778,12 @@ do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *
PROC_UNLOCK(p2);
sx_xunlock(&proctree_lock);
}
racct_proc_fork_done(p2);
if ((fr->fr_flags & RFSTOPPED) == 0) {
if (fr->fr_pidp != NULL)
*fr->fr_pidp = p2->p_pid;
/*
* If RFSTOPPED not requested, make child runnable and
* add to run queue.
@ -793,16 +792,9 @@ do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *
TD_SET_CAN_RUN(td2);
sched_add(td2, SRQ_BORING);
thread_unlock(td2);
if (fr->fr_pidp != NULL)
*fr->fr_pidp = p2->p_pid;
} else {
*fr->fr_procp = p2;
}
PROC_LOCK(p2);
_PRELE(p2);
racct_proc_fork_done(p2);
PROC_UNLOCK(p2);
}
int

4
sys/kern/kern_racct.c
View File

@ -967,13 +967,13 @@ racct_proc_fork_done(struct proc *child)
if (!racct_enable)
return;
PROC_LOCK_ASSERT(child, MA_OWNED);
#ifdef RCTL
PROC_LOCK(child);
RACCT_LOCK();
rctl_enforce(child, RACCT_NPROC, 0);
rctl_enforce(child, RACCT_NTHR, 0);
RACCT_UNLOCK();
PROC_UNLOCK(child);
#endif
}