d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

The td_waitset is pointing to a stack address when thread is waiting

Browse Source 
for a signal, because kernel stack is swappable, this causes page fault
in kernel under heavy swapping case. Fix this bug by eliminating unneeded
code.
This commit is contained in:
David Xu 2005-03-04 22:46:31 +00:00
parent 6d93d4fb04
commit 627451c1d9
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=143144
2 changed files with 6 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
sys/kern/kern_sig.c
View File

@ -921,12 +921,10 @@ kern_sigtimedwait(struct thread *td, sigset_t waitset, siginfo_t *info,
} else
hz = 0;
td->td_waitset = &waitset;
td->td_sigmask = savedmask;
SIGSETNAND(td->td_sigmask, waitset);
signotify(td);
error = msleep(&ps, &p->p_mtx, PPAUSE|PCATCH, "sigwait", hz);
td->td_waitset = NULL;
if (timeout) {
if (error == ERESTART) {
/* timeout can not be restarted. */
@ -1577,28 +1575,17 @@ sigtd(struct proc *p, int sig, int prop)
PROC_LOCK_ASSERT(p, MA_OWNED);
/*
* First find a thread in sigwait state and signal belongs to
* its wait set. POSIX's arguments is that speed of delivering signal
* to sigwait thread is faster than delivering signal to user stack.
* If we can not find sigwait thread, then find the first thread in
* the proc that doesn't have this signal masked, an exception is
* if current thread is sending signal to its process, and it does not
* mask the signal, it should get the signal, this is another fast
* way to deliver signal.
* Check if current thread can handle the signal without
* switching conetxt to another thread.
*/
if (curproc == p && !SIGISMEMBER(curthread->td_sigmask, sig))
return (curthread);
signal_td = NULL;
mtx_lock_spin(&sched_lock);
FOREACH_THREAD_IN_PROC(p, td) {
if (td->td_waitset != NULL &&
SIGISMEMBER(*(td->td_waitset), sig)) {
mtx_unlock_spin(&sched_lock);
return (td);
}
if (!SIGISMEMBER(td->td_sigmask, sig)) {
if (td == curthread)
signal_td = curthread;
else if (signal_td == NULL)
signal_td = td;
signal_td = td;
break;
}
}
if (signal_td == NULL)

1
sys/sys/proc.h
View File

@ -281,7 +281,6 @@ struct thread {
sigset_t td_oldsigmask; /* (k) Saved mask from pre sigpause. */
sigset_t td_sigmask; /* (c) Current signal mask. */
sigset_t td_siglist; /* (c) Sigs arrived, not delivered. */
sigset_t *td_waitset; /* (c) Wait set for sigwait. */
struct umtx_q *td_umtxq; /* (c?) Link for when we're blocked. */
volatile u_int td_generation; /* (k) For detection of preemption */
stack_t td_sigstk; /* (k) Stack ptr and on-stack flag. */