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The assertion re-added in r302614 was triggered when stopping signal

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is delivered to vforked child.  Issue is that we avoid stopping such
children in issignal() to not block parents.  But executed AST, which
ignored stops, leaves the child with the signal pending but no AST
pending.

On first exec after vfork(), call signotify() to handle pending
reenabled signals.  Adjust the assert to not check vfork children
until exec.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2016-07-18 10:53:47 +00:00
parent 809a9d1353
commit 77d6809483
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=302999
2 changed files with 20 additions and 10 deletions
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2
sys/kern/kern_exec.c
View File

@ -760,6 +760,8 @@ do_execve(td, args, mac_p)
if (p->p_flag & P_PPWAIT) {
p->p_flag &= ~(P_PPWAIT | P_PPTRACE);
cv_broadcast(&p->p_pwait);
/* STOPs are no longer ignored, arrange for AST */
signotify(td);
}
/*

28
sys/kern/subr_trap.c
View File

@ -107,15 +107,20 @@ userret(struct thread *td, struct trapframe *frame)
* multi-threaded processes, where signal distribution might
* change due to other threads changing sigmask, the check is
* racy and cannot be performed reliably.
* If current process is vfork child, indicated by P_PPWAIT, then
* issignal() ignores stops, so we block the check to avoid
* classifying pending signals.
*/
if (p->p_numthreads == 1) {
PROC_LOCK(p);
thread_lock(td);
KASSERT(!SIGPENDING(td) ||
(td->td_flags & (TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
(TDF_NEEDSIGCHK | TDF_ASTPENDING),
("failed to set signal flags for ast p %p td %p fl %x",
p, td, td->td_flags));
if ((p->p_flag & P_PPWAIT) == 0) {
KASSERT(!SIGPENDING(td) || (td->td_flags &
(TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
(TDF_NEEDSIGCHK | TDF_ASTPENDING),
("failed to set signal flags for ast p %p "
"td %p fl %x", p, td, td->td_flags));
}
thread_unlock(td);
PROC_UNLOCK(p);
}
@ -281,12 +286,15 @@ ast(struct trapframe *framep)
* td_flags, since signal might have been delivered
* after we cleared td_flags above. This is one of
* the reason for looping check for AST condition.
* See comment in userret() about P_PPWAIT.
*/
KASSERT(!SIGPENDING(td) ||
(td->td_flags & (TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
(TDF_NEEDSIGCHK | TDF_ASTPENDING),
("failed2 to set signal flags for ast p %p td %p fl %x %x",
p, td, flags, td->td_flags));
if ((p->p_flag & P_PPWAIT) == 0) {
KASSERT(!SIGPENDING(td) || (td->td_flags &
(TDF_NEEDSIGCHK | TDF_ASTPENDING)) ==
(TDF_NEEDSIGCHK | TDF_ASTPENDING),
("failed2 to set signal flags for ast p %p td %p "
"fl %x %x", p, td, flags, td->td_flags));
}
thread_unlock(td);
PROC_UNLOCK(p);
}