Module Name: src
Committed By: ad
Date: Thu Mar 26 20:19:06 UTC 2020
Modified Files:
src/sys/kern: kern_lwp.c kern_softint.c
src/sys/sys: intr.h userret.h
Log Message:
softint_overlay() (slow case) gains ~nothing but creates potential headaches.
In the interests of simplicity remove it and always use the kthreads.
To generate a diff of this commit:
cvs rdiff -u -r1.229 -r1.230 src/sys/kern/kern_lwp.c
cvs rdiff -u -r1.62 -r1.63 src/sys/kern/kern_softint.c
cvs rdiff -u -r1.19 -r1.20 src/sys/sys/intr.h
cvs rdiff -u -r1.32 -r1.33 src/sys/sys/userret.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_lwp.c
diff -u src/sys/kern/kern_lwp.c:1.229 src/sys/kern/kern_lwp.c:1.230
--- src/sys/kern/kern_lwp.c:1.229 Sun Mar 8 17:04:45 2020
+++ src/sys/kern/kern_lwp.c Thu Mar 26 20:19:06 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_lwp.c,v 1.229 2020/03/08 17:04:45 ad Exp $ */
+/* $NetBSD: kern_lwp.c,v 1.230 2020/03/26 20:19:06 ad Exp $ */
/*-
* Copyright (c) 2001, 2006, 2007, 2008, 2009, 2019, 2020
@@ -211,7 +211,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.229 2020/03/08 17:04:45 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.230 2020/03/26 20:19:06 ad Exp $");
#include "opt_ddb.h"
#include "opt_lockdebug.h"
@@ -1593,12 +1593,6 @@ lwp_userret(struct lwp *l)
KASSERT(l->l_stat == LSONPROC);
p = l->l_proc;
-#ifndef __HAVE_FAST_SOFTINTS
- /* Run pending soft interrupts. */
- if (l->l_cpu->ci_data.cpu_softints != 0)
- softint_overlay();
-#endif
-
/*
* It is safe to do this read unlocked on a MP system..
*/
Index: src/sys/kern/kern_softint.c
diff -u src/sys/kern/kern_softint.c:1.62 src/sys/kern/kern_softint.c:1.63
--- src/sys/kern/kern_softint.c:1.62 Sun Mar 8 15:05:18 2020
+++ src/sys/kern/kern_softint.c Thu Mar 26 20:19:06 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_softint.c,v 1.62 2020/03/08 15:05:18 ad Exp $ */
+/* $NetBSD: kern_softint.c,v 1.63 2020/03/26 20:19:06 ad Exp $ */
/*-
* Copyright (c) 2007, 2008, 2019, 2020 The NetBSD Foundation, Inc.
@@ -170,7 +170,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_softint.c,v 1.62 2020/03/08 15:05:18 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_softint.c,v 1.63 2020/03/26 20:19:06 ad Exp $");
#include <sys/param.h>
#include <sys/proc.h>
@@ -196,7 +196,7 @@ typedef struct softint {
uintptr_t si_machdep;
struct evcnt si_evcnt;
struct evcnt si_evcnt_block;
- int si_active;
+ volatile int si_active;
char si_name[8];
char si_name_block[8+6];
} softint_t;
@@ -546,11 +546,7 @@ softint_execute(softint_t *si, lwp_t *l,
{
softhand_t *sh;
-#ifdef __HAVE_FAST_SOFTINTS
KASSERT(si->si_lwp == curlwp);
-#else
- /* May be running in user context. */
-#endif
KASSERT(si->si_cpu == curcpu());
KASSERT(si->si_lwp->l_wchan == NULL);
KASSERT(si->si_active);
@@ -678,12 +674,22 @@ softint_trigger(uintptr_t machdep)
ci = curcpu();
ci->ci_data.cpu_softints |= machdep;
l = ci->ci_onproc;
+
+ /*
+ * Arrange for mi_switch() to be called. If called from interrupt
+ * mode, we don't know if curlwp is executing in kernel or user, so
+ * post an AST and have it take a trip through userret(). If not in
+ * interrupt mode, curlwp is running in kernel and will notice the
+ * resched soon enough; avoid the AST.
+ */
if (l == ci->ci_data.cpu_idlelwp) {
atomic_or_uint(&ci->ci_want_resched,
RESCHED_IDLE | RESCHED_UPREEMPT);
} else {
- /* MI equivalent of aston() */
- cpu_signotify(l);
+ atomic_or_uint(&ci->ci_want_resched, RESCHED_UPREEMPT);
+ if (cpu_intr_p()) {
+ cpu_signotify(l);
+ }
}
}
@@ -754,65 +760,6 @@ softint_picklwp(void)
return l;
}
-/*
- * softint_overlay:
- *
- * Slow path: called from lwp_userret() to run a soft interrupt
- * within the context of a user thread.
- */
-void
-softint_overlay(void)
-{
- struct cpu_info *ci;
- u_int softints, oflag;
- softint_t *si;
- pri_t obase;
- lwp_t *l;
- int s;
-
- l = curlwp;
- KASSERT((l->l_pflag & LP_INTR) == 0);
-
- /*
- * Arrange to elevate priority if the LWP blocks. Also, bind LWP
- * to the CPU. Note: disable kernel preemption before doing that.
- */
- s = splhigh();
- ci = l->l_cpu;
- si = ((softcpu_t *)ci->ci_data.cpu_softcpu)->sc_int;
-
- obase = l->l_kpribase;
- l->l_kpribase = PRI_KERNEL_RT;
- oflag = l->l_pflag;
- l->l_pflag = oflag | LP_INTR | LP_BOUND;
-
- while ((softints = ci->ci_data.cpu_softints) != 0) {
- if ((softints & (1 << SOFTINT_SERIAL)) != 0) {
- ci->ci_data.cpu_softints &= ~(1 << SOFTINT_SERIAL);
- softint_execute(&si[SOFTINT_SERIAL], l, s);
- continue;
- }
- if ((softints & (1 << SOFTINT_NET)) != 0) {
- ci->ci_data.cpu_softints &= ~(1 << SOFTINT_NET);
- softint_execute(&si[SOFTINT_NET], l, s);
- continue;
- }
- if ((softints & (1 << SOFTINT_BIO)) != 0) {
- ci->ci_data.cpu_softints &= ~(1 << SOFTINT_BIO);
- softint_execute(&si[SOFTINT_BIO], l, s);
- continue;
- }
- if ((softints & (1 << SOFTINT_CLOCK)) != 0) {
- ci->ci_data.cpu_softints &= ~(1 << SOFTINT_CLOCK);
- softint_execute(&si[SOFTINT_CLOCK], l, s);
- continue;
- }
- }
- l->l_pflag = oflag;
- l->l_kpribase = obase;
- splx(s);
-}
-
#else /* !__HAVE_FAST_SOFTINTS */
/*
@@ -892,20 +839,13 @@ softint_dispatch(lwp_t *pinned, int s)
/*
* If we blocked while handling the interrupt, the pinned LWP is
- * gone so switch to the idle LWP. It will select a new LWP to
- * run.
- *
- * We must drop the priority level as switching at IPL_HIGH could
- * deadlock the system. We have already set si->si_active = 0,
- * which means another interrupt at this level can be triggered.
- * That's not be a problem: we are lowering to level 's' which will
- * prevent softint_dispatch() from being reentered at level 's',
- * until the priority is finally dropped to IPL_NONE on entry to
- * the LWP chosen by mi_switch().
+ * gone, so find another LWP to run. It will select a new LWP to
+ * run. softint_dispatch() won't be reentered until the priority
+ * is finally dropped to IPL_NONE on entry to the LWP chosen by
+ * mi_switch().
*/
l->l_stat = LSIDL;
if (l->l_switchto == NULL) {
- splx(s);
lwp_lock(l);
spc_lock(l->l_cpu);
mi_switch(l);
Index: src/sys/sys/intr.h
diff -u src/sys/sys/intr.h:1.19 src/sys/sys/intr.h:1.20
--- src/sys/sys/intr.h:1.19 Mon Aug 17 06:16:03 2015
+++ src/sys/sys/intr.h Thu Mar 26 20:19:06 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: intr.h,v 1.19 2015/08/17 06:16:03 knakahara Exp $ */
+/* $NetBSD: intr.h,v 1.20 2020/03/26 20:19:06 ad Exp $ */
/*-
* Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -50,7 +50,6 @@ void softint_schedule_cpu(void *, struct
/* MI hooks. */
void softint_init(struct cpu_info *);
lwp_t *softint_picklwp(void);
-void softint_overlay(void);
void softint_block(lwp_t *);
/* MD-MI interface. */
Index: src/sys/sys/userret.h
diff -u src/sys/sys/userret.h:1.32 src/sys/sys/userret.h:1.33
--- src/sys/sys/userret.h:1.32 Wed Jan 22 12:23:04 2020
+++ src/sys/sys/userret.h Thu Mar 26 20:19:06 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: userret.h,v 1.32 2020/01/22 12:23:04 ad Exp $ */
+/* $NetBSD: userret.h,v 1.33 2020/03/26 20:19:06 ad Exp $ */
/*-
* Copyright (c) 1998, 2000, 2003, 2006, 2008, 2019, 2020
@@ -91,11 +91,7 @@ mi_userret(struct lwp *l)
preempt();
ci = l->l_cpu;
}
-#ifdef __HAVE_FAST_SOFTINTS
if (__predict_false(l->l_flag & LW_USERRET)) {
-#else
- if (((l->l_flag & LW_USERRET) | ci->ci_data.cpu_softints) != 0) {
-#endif
KPREEMPT_ENABLE(l);
lwp_userret(l);
KPREEMPT_DISABLE(l);
