SA fixes from Stephan Uphoff. Quoting him:
The patch below (hopefully) improves some signaling problems found by Nathan. It also contains some cleanup of the sa_upcall_userret() function removing any sleep calls using PCATCH. Unblocked threads now only use an upcall stack after they acquire the virtual CPU. This prevents unblocked threads from stealing all available upcall stacks. Tested by Nick Hudson.
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fvdl
parent
8c1a2eef97
commit
8655b27bf5
@ -1,4 +1,4 @@
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/* $NetBSD: kern_sa.c,v 1.19 2003/07/21 19:21:12 nathanw Exp $ */
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/* $NetBSD: kern_sa.c,v 1.20 2003/08/11 21:18:18 fvdl Exp $ */
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/*-
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* Copyright (c) 2001 The NetBSD Foundation, Inc.
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@ -37,7 +37,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_sa.c,v 1.19 2003/07/21 19:21:12 nathanw Exp $");
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__KERNEL_RCSID(0, "$NetBSD: kern_sa.c,v 1.20 2003/08/11 21:18:18 fvdl Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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@ -209,8 +209,13 @@ sys_sa_stacks(struct lwp *l, void *v, register_t *retval)
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sizeof(stack_t) * count);
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if (error)
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return (error);
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if ((sa->sa_nstacks == 0) && (sa->sa_vp_wait_count != 0))
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{
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l->l_flag |= L_SA_UPCALL;
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}
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sa->sa_nstacks += count;
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wakeup((caddr_t)&sa->sa_nstacks);
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DPRINTFN(9, ("sa_stacks(%d.%d) nstacks + %d = %2d\n",
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l->l_proc->p_pid, l->l_lid, count, sa->sa_nstacks));
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@ -701,15 +706,10 @@ sa_switch(struct lwp *l, int type)
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/*
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* Okay, now we've been woken up. This means that it's time
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* for a SA_UNBLOCKED upcall when we get back to userlevel, provided
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* that the SA_BLOCKED upcall happened.
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* for a SA_UNBLOCKED upcall when we get back to userlevel
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*/
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if (l->l_flag & L_SA_BLOCKING)
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l->l_flag |= L_SA_UPCALL;
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#if 0
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else
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sa_vp_repossess(l);
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#endif
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l->l_flag |= L_SA_UPCALL;
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}
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void
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@ -885,66 +885,19 @@ sa_upcall_userret(struct lwp *l)
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sau = sadata_upcall_alloc(1);
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sau->sau_arg = NULL;
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while (sa->sa_nstacks == 0) {
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int status;
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/*
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* This should be a transient condition, so we'll just
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* sleep until some stacks come in; presumably, some
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* userland LWP is busy and hasn't gotten to return
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* stacks yet.
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*
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* XXX There is a slight protocol breach here, in
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* that control is not handed back directly to the
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* LWP that was running before we were woken up from
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* the sleep that invoked the UNBLOCKED upcall.
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* If it was a running one, it is on the runqueue
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* and it will run again when the system gets to it,
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* just not this second. If it's idle, it will
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* remain idle, because we don't touch it.
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*
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* Ideally, tsleep() would have a variant that took
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* a LWP to switch to.
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*/
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if (p->p_flag & P_WEXIT)
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{
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sadata_upcall_free(sau);
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lwp_exit(l);
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}
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DPRINTFN(7, ("sa_upcall_userret(%d.%d) sleeping"
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" for stacks\n", l->l_proc->p_pid, l->l_lid));
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status = tsleep((caddr_t) &sa->sa_nstacks, PWAIT|PCATCH,
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"sastacks", 0);
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if(status)
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{
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if (p->p_flag & P_WEXIT)
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{
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sadata_upcall_free(sau);
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lwp_exit(l);
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}
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/* Signal pending - can't sleep */
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/* Wait a while .. things might get better */
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tsleep((caddr_t) &lbolt, PWAIT, "lbolt: sastacks", 0);
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}
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/* XXXUPSXXX NEED TO STOP THE LWP HERE ON REQUEST */
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}
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if (p->p_flag & P_WEXIT) {
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sadata_upcall_free(sau);
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lwp_exit(l);
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}
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KDASSERT(sa->sa_nstacks > 0);
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st = sa->sa_stacks[--sa->sa_nstacks];
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SCHED_ASSERT_UNLOCKED();
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l2 = sa_vp_repossess(l);
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KDASSERT(sa->sa_nstacks > 0);
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st = sa->sa_stacks[--sa->sa_nstacks];
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SCHED_ASSERT_UNLOCKED();
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@ -1242,9 +1195,14 @@ sa_vp_donate(struct lwp *l)
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SCHED_ASSERT_UNLOCKED();
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/* Nobody wants the vp */
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if (sa->sa_vp_wait_count == 0)
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return;
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/* No stack for an unblock call */
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if (sa->sa_nstacks == 0)
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return;
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LIST_FOREACH(l2, &p->p_lwps, l_sibling) {
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if(l2->l_flag & L_SA_WANTS_VP) {
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SCHED_LOCK(s);
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@ -1,4 +1,4 @@
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/* $NetBSD: kern_sig.c,v 1.146 2003/08/07 16:31:48 agc Exp $ */
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/* $NetBSD: kern_sig.c,v 1.147 2003/08/11 21:18:19 fvdl Exp $ */
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/*
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* Copyright (c) 1982, 1986, 1989, 1991, 1993
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@ -37,7 +37,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.146 2003/08/07 16:31:48 agc Exp $");
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__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.147 2003/08/11 21:18:19 fvdl Exp $");
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#include "opt_ktrace.h"
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#include "opt_compat_sunos.h"
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@ -888,7 +888,8 @@ psignal1(struct proc *p, int signum,
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SCHED_LOCK(s);
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/* XXXUPSXXX LWPs might go to sleep without passing signal handling */
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if (p->p_nrlwps > 0 && (p->p_stat != SSTOP)) {
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if (p->p_nrlwps > 0 && (p->p_stat != SSTOP)
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&& !((p->p_flag & P_SA) && (p->p_sa->sa_idle != NULL))) {
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/*
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* At least one LWP is running or on a run queue.
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* The signal will be noticed when one of them returns
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@ -931,8 +932,7 @@ psignal1(struct proc *p, int signum,
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}
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}
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if (p->p_stat == SACTIVE) {
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/* All LWPs must be sleeping */
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KDASSERT(((p->p_flag & P_SA) == 0) || (l != NULL));
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if (l != NULL && (p->p_flag & P_TRACED))
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goto run;
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