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- Don't hold the proc lock across VREF and the fd* functions to avoid lock

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order reversals.
- Add some preliminary locking in the !RF_PROC case.
- Protect p_estcpu with sched_lock.
This commit is contained in:
John Baldwin 2001-03-07 05:21:47 +00:00
parent e238d2a8da
commit 5641ae5dc3
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=73935
1 changed files with 21 additions and 4 deletions
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25
sys/kern/kern_fork.c
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@ -207,6 +207,7 @@ fork1(p1, flags, procp)
int ok;
static int pidchecked = 0;
struct forklist *ep;
struct filedesc *fd;
/* Can't copy and clear */
if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
@ -226,8 +227,10 @@ fork1(p1, flags, procp)
if (flags & RFCFDG) {
struct filedesc *fdtmp;
fdtmp = fdinit(p1);
PROC_LOCK(p1);
fdfree(p1);
p1->p_fd = fdtmp;
PROC_UNLOCK(p1);
}
/*
@ -237,8 +240,10 @@ fork1(p1, flags, procp)
if (p1->p_fd->fd_refcnt > 1) {
struct filedesc *newfd;
newfd = fdcopy(p1);
PROC_LOCK(p1);
fdfree(p1);
p1->p_fd = newfd;
PROC_UNLOCK(p1);
}
}
*procp = NULL;
@ -456,15 +461,19 @@ fork1(p1, flags, procp)
/* bump references to the text vnode (for procfs) */
p2->p_textvp = p1->p_textvp;
PROC_UNLOCK(p1);
PROC_UNLOCK(p2);
if (p2->p_textvp)
VREF(p2->p_textvp);
if (flags & RFCFDG)
p2->p_fd = fdinit(p1);
fd = fdinit(p1);
else if (flags & RFFDG)
p2->p_fd = fdcopy(p1);
fd = fdcopy(p1);
else
p2->p_fd = fdshare(p1);
fd = fdshare(p1);
PROC_LOCK(p2);
p2->p_fd = fd;
/*
* If p_limit is still copy-on-write, bump refcnt,
@ -472,6 +481,7 @@ fork1(p1, flags, procp)
* (If PL_SHAREMOD is clear, the structure is shared
* copy-on-write.)
*/
PROC_LOCK(p1);
if (p1->p_limit->p_lflags & PL_SHAREMOD)
p2->p_limit = limcopy(p1->p_limit);
else {
@ -526,15 +536,22 @@ fork1(p1, flags, procp)
*/
if (p1->p_traceflag & KTRFAC_INHERIT) {
p2->p_traceflag = p1->p_traceflag;
if ((p2->p_tracep = p1->p_tracep) != NULL)
if ((p2->p_tracep = p1->p_tracep) != NULL) {
PROC_UNLOCK(p1);
PROC_UNLOCK(p2);
VREF(p2->p_tracep);
PROC_LOCK(p2);
PROC_LOCK(p1);
}
}
#endif
/*
* set priority of child to be that of parent
*/
mtx_lock_spin(&sched_lock);
p2->p_estcpu = p1->p_estcpu;
mtx_unlock_spin(&sched_lock);
/*
* This begins the section where we must prevent the parent