Module Name: src
Committed By: ad
Date: Fri Oct 13 18:48:56 UTC 2023
Modified Files:
src/sys/kern: kern_condvar.c kern_sleepq.c
src/sys/rump/librump/rumpkern: locks.c locks_up.c
src/sys/sys: condvar.h lwp.h
Log Message:
Add cv_fdrestart() (better name suggestions welcome):
Like cv_broadcast(), but make any LWPs that share the same file descriptor
table as the caller return ERESTART when resuming. Used to dislodge LWPs
waiting for I/O that prevent a file descriptor from being closed, without
upsetting access to the file (not descriptor) made from another direction.
To generate a diff of this commit:
cvs rdiff -u -r1.59 -r1.60 src/sys/kern/kern_condvar.c
cvs rdiff -u -r1.83 -r1.84 src/sys/kern/kern_sleepq.c
cvs rdiff -u -r1.86 -r1.87 src/sys/rump/librump/rumpkern/locks.c
cvs rdiff -u -r1.12 -r1.13 src/sys/rump/librump/rumpkern/locks_up.c
cvs rdiff -u -r1.17 -r1.18 src/sys/sys/condvar.h
cvs rdiff -u -r1.227 -r1.228 src/sys/sys/lwp.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_condvar.c
diff -u src/sys/kern/kern_condvar.c:1.59 src/sys/kern/kern_condvar.c:1.60
--- src/sys/kern/kern_condvar.c:1.59 Thu Oct 12 23:51:05 2023
+++ src/sys/kern/kern_condvar.c Fri Oct 13 18:48:56 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_condvar.c,v 1.59 2023/10/12 23:51:05 ad Exp $ */
+/* $NetBSD: kern_condvar.c,v 1.60 2023/10/13 18:48:56 ad Exp $ */
/*-
* Copyright (c) 2006, 2007, 2008, 2019, 2020, 2023
@@ -35,7 +35,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_condvar.c,v 1.59 2023/10/12 23:51:05 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_condvar.c,v 1.60 2023/10/13 18:48:56 ad Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -543,6 +543,43 @@ cv_wakeup_all(kcondvar_t *cv)
}
/*
+ * cv_fdrestart:
+ *
+ * Like cv_broadcast(), but make any LWPs that share the same file
+ * descriptor table as the caller return ERESTART when resuming. Used
+ * to dislodge LWPs waiting for I/O that prevent a file descriptor from
+ * being closed, without upsetting access to the file (not descriptor)
+ * made from another direction. Rarely used thus no fast path
+ * provided.
+ */
+void
+cv_fdrestart(kcondvar_t *cv)
+{
+ sleepq_t *sq;
+ kmutex_t *mp;
+ lwp_t *l;
+
+ KASSERT(cv_is_valid(cv));
+
+ if (LIST_EMPTY(CV_SLEEPQ(cv)))
+ return;
+
+ mp = sleepq_hashlock(cv);
+ sq = CV_SLEEPQ(cv);
+ while ((l = LIST_FIRST(sq)) != NULL) {
+ KASSERT(l->l_sleepq == sq);
+ KASSERT(l->l_mutex == mp);
+ KASSERT(l->l_wchan == cv);
+ /* l_fd stable at this point so no special locking needed. */
+ if (l->l_fd == curlwp->l_fd) {
+ l->l_flag |= LW_RESTART;
+ sleepq_remove(sq, l, false);
+ }
+ }
+ mutex_spin_exit(mp);
+}
+
+/*
* cv_has_waiters:
*
* For diagnostic assertions: return non-zero if a condition
Index: src/sys/kern/kern_sleepq.c
diff -u src/sys/kern/kern_sleepq.c:1.83 src/sys/kern/kern_sleepq.c:1.84
--- src/sys/kern/kern_sleepq.c:1.83 Sun Oct 8 13:37:26 2023
+++ src/sys/kern/kern_sleepq.c Fri Oct 13 18:48:56 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_sleepq.c,v 1.83 2023/10/08 13:37:26 ad Exp $ */
+/* $NetBSD: kern_sleepq.c,v 1.84 2023/10/13 18:48:56 ad Exp $ */
/*-
* Copyright (c) 2006, 2007, 2008, 2009, 2019, 2020, 2023
@@ -36,7 +36,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_sleepq.c,v 1.83 2023/10/08 13:37:26 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_sleepq.c,v 1.84 2023/10/13 18:48:56 ad Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
@@ -341,7 +341,7 @@ sleepq_uncatch(lwp_t *l)
int
sleepq_block(int timo, bool catch_p, syncobj_t *syncobj, int nlocks)
{
- const int mask = LW_CANCELLED|LW_WEXIT|LW_WCORE|LW_PENDSIG;
+ const int mask = LW_CANCELLED|LW_WEXIT|LW_WCORE|LW_PENDSIG|LW_RESTART;
int error = 0, sig, flag;
struct proc *p;
lwp_t *l = curlwp;
@@ -358,16 +358,20 @@ sleepq_block(int timo, bool catch_p, syn
* while we are sleeping. It is independent from LW_SINTR because
* we don't want to leave LW_SINTR set when the LWP is not asleep.
*/
+ flag = l->l_flag;
if (catch_p) {
- if ((l->l_flag & (LW_CANCELLED|LW_WEXIT|LW_WCORE)) != 0) {
- l->l_flag &= ~LW_CANCELLED;
- error = EINTR;
- early = true;
- } else if ((l->l_flag & LW_PENDSIG) != 0 && sigispending(l, 0))
- early = true;
- l->l_flag |= LW_CATCHINTR;
+ if ((flag & mask) != 0) {
+ if ((flag & (LW_CANCELLED|LW_WEXIT|LW_WCORE)) != 0) {
+ l->l_flag = flag & ~LW_CANCELLED;
+ error = EINTR;
+ early = true;
+ } else if ((flag & LW_PENDSIG) != 0 &&
+ sigispending(l, 0))
+ early = true;
+ }
+ l->l_flag = (flag | LW_CATCHINTR) & ~LW_RESTART;
} else
- l->l_flag &= ~LW_CATCHINTR;
+ l->l_flag = flag & ~(LW_CATCHINTR | LW_RESTART);
if (early) {
/* lwp_unsleep() will release the lock */
@@ -435,7 +439,8 @@ sleepq_block(int timo, bool catch_p, syn
(sig = issignal(l)) != 0)
error = sleepq_sigtoerror(l, sig);
mutex_exit(p->p_lock);
- }
+ } else if ((flag & LW_RESTART) != 0)
+ error = ERESTART;
}
ktrcsw(0, 0, syncobj);
Index: src/sys/rump/librump/rumpkern/locks.c
diff -u src/sys/rump/librump/rumpkern/locks.c:1.86 src/sys/rump/librump/rumpkern/locks.c:1.87
--- src/sys/rump/librump/rumpkern/locks.c:1.86 Sun Jul 16 23:12:17 2023
+++ src/sys/rump/librump/rumpkern/locks.c Fri Oct 13 18:48:56 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: locks.c,v 1.86 2023/07/16 23:12:17 riastradh Exp $ */
+/* $NetBSD: locks.c,v 1.87 2023/10/13 18:48:56 ad Exp $ */
/*
* Copyright (c) 2007-2011 Antti Kantee. All Rights Reserved.
@@ -26,7 +26,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: locks.c,v 1.86 2023/07/16 23:12:17 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locks.c,v 1.87 2023/10/13 18:48:56 ad Exp $");
#include <sys/param.h>
#include <sys/kmem.h>
@@ -486,6 +486,13 @@ cv_broadcast(kcondvar_t *cv)
rumpuser_cv_broadcast(RUMPCV(cv));
}
+void
+cv_fdrestart(kcondvar_t *cv)
+{
+
+ rumpuser_cv_broadcast(RUMPCV(cv));
+}
+
bool
cv_has_waiters(kcondvar_t *cv)
{
Index: src/sys/rump/librump/rumpkern/locks_up.c
diff -u src/sys/rump/librump/rumpkern/locks_up.c:1.12 src/sys/rump/librump/rumpkern/locks_up.c:1.13
--- src/sys/rump/librump/rumpkern/locks_up.c:1.12 Wed Apr 12 06:35:40 2023
+++ src/sys/rump/librump/rumpkern/locks_up.c Fri Oct 13 18:48:56 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: locks_up.c,v 1.12 2023/04/12 06:35:40 riastradh Exp $ */
+/* $NetBSD: locks_up.c,v 1.13 2023/10/13 18:48:56 ad Exp $ */
/*
* Copyright (c) 2010 Antti Kantee. All Rights Reserved.
@@ -35,7 +35,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: locks_up.c,v 1.12 2023/04/12 06:35:40 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locks_up.c,v 1.13 2023/10/13 18:48:56 ad Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
@@ -421,6 +421,14 @@ cv_broadcast(kcondvar_t *cv)
rumpuser_cv_broadcast(RUMPCV(cv));
}
+void
+cv_fdrestart(kcondvar_t *cv)
+{
+
+ /* CPU == interlock */
+ rumpuser_cv_broadcast(RUMPCV(cv));
+}
+
bool
cv_has_waiters(kcondvar_t *cv)
{
Index: src/sys/sys/condvar.h
diff -u src/sys/sys/condvar.h:1.17 src/sys/sys/condvar.h:1.18
--- src/sys/sys/condvar.h:1.17 Mon May 11 03:59:33 2020
+++ src/sys/sys/condvar.h Fri Oct 13 18:48:56 2023
@@ -1,7 +1,7 @@
-/* $NetBSD: condvar.h,v 1.17 2020/05/11 03:59:33 riastradh Exp $ */
+/* $NetBSD: condvar.h,v 1.18 2023/10/13 18:48:56 ad Exp $ */
/*-
- * Copyright (c) 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc.
+ * Copyright (c) 2006, 2007, 2008, 2020, 2023 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -56,6 +56,7 @@ int cv_timedwaitbt_sig(kcondvar_t *, str
void cv_signal(kcondvar_t *);
void cv_broadcast(kcondvar_t *);
+void cv_fdrestart(kcondvar_t *);
bool cv_has_waiters(kcondvar_t *);
bool cv_is_valid(kcondvar_t *);
Index: src/sys/sys/lwp.h
diff -u src/sys/sys/lwp.h:1.227 src/sys/sys/lwp.h:1.228
--- src/sys/sys/lwp.h:1.227 Thu Oct 5 19:41:07 2023
+++ src/sys/sys/lwp.h Fri Oct 13 18:48:56 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: lwp.h,v 1.227 2023/10/05 19:41:07 ad Exp $ */
+/* $NetBSD: lwp.h,v 1.228 2023/10/13 18:48:56 ad Exp $ */
/*
* Copyright (c) 2001, 2006, 2007, 2008, 2009, 2010, 2019, 2020, 2023
@@ -266,6 +266,7 @@ extern int maxlwp __read_mostly; /* max
#define LW_CACHECRED 0x04000000 /* Cache new process credential */
#define LW_WREBOOT 0x08000000 /* System is rebooting, please suspend */
#define LW_UNPARKED 0x10000000 /* Unpark op pending */
+#define LW_RESTART 0x20000000 /* Return ERESTART after waking */
#define LW_RUMP_CLEAR 0x40000000 /* Clear curlwp in RUMP scheduler */
#define LW_RUMP_QEXIT 0x80000000 /* LWP should exit ASAP */
