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[src/trunk]: src/lib/librumpclient On Linux, poll signalfd() when waiting for...
details: https://anonhg.NetBSD.org/src/rev/41d44c111da4
branches: trunk
changeset: 328401:41d44c111da4
user: pooka <pooka%NetBSD.org@localhost>
date: Wed Apr 02 14:48:03 2014 +0000
description:
On Linux, poll signalfd() when waiting for a kernel response.
This allows the same type of race-free handling of signals as kqueue()
allows on NetBSD. One of the noticeable things is that you can now
interrupt rumprun ping mid-interval on Linux.
per suggestion from Justin Cormack
diffstat:
lib/librumpclient/rumpclient.c | 162 ++++++++++++++++++++++++++--------------
1 files changed, 105 insertions(+), 57 deletions(-)
diffs (truncated from 313 to 300 lines):
diff -r 972c11638567 -r 41d44c111da4 lib/librumpclient/rumpclient.c
--- a/lib/librumpclient/rumpclient.c Wed Apr 02 14:11:25 2014 +0000
+++ b/lib/librumpclient/rumpclient.c Wed Apr 02 14:48:03 2014 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: rumpclient.c,v 1.57 2014/02/26 02:03:40 pooka Exp $ */
+/* $NetBSD: rumpclient.c,v 1.58 2014/04/02 14:48:03 pooka Exp $ */
/*
* Copyright (c) 2010, 2011 Antti Kantee. All Rights Reserved.
@@ -38,17 +38,19 @@
* notifications but defer their handling to a stage where we do not
* hold the communication lock. Taking a signal while holding on to
* that lock may cause a deadlock. Therefore, block signals throughout
- * the RPC when using poll. This unfortunately means that the normal
- * SIGINT way of stopping a process while it is undergoing rump kernel
- * RPC will not work. If anyone know which Linux system call handles
- * the above scenario correctly, I'm all ears.
+ * the RPC when using poll. On Linux, we use signalfd in the same role
+ * as kqueue on NetBSD to be able to take signals while waiting for a
+ * response from the server.
*/
#ifdef __NetBSD__
#define USE_KQUEUE
#endif
+#ifdef __linux__
+#define USE_SIGNALFD
+#endif
-__RCSID("$NetBSD: rumpclient.c,v 1.57 2014/02/26 02:03:40 pooka Exp $");
+__RCSID("$NetBSD: rumpclient.c,v 1.58 2014/04/02 14:48:03 pooka Exp $");
#include <sys/param.h>
#include <sys/mman.h>
@@ -96,6 +98,12 @@
struct kevent *, size_t, const struct timespec *);
#endif
+#ifdef USE_SIGNALFD
+#include <sys/signalfd.h>
+
+int (*host_signalfd)(int, const sigset_t *, int);
+#endif
+
int (*host_execve)(const char *, char *const[], char *const[]);
#include "sp_common.c"
@@ -105,7 +113,7 @@
.spc_fd = -1,
};
-static int kq = -1;
+static int holyfd;
static sigset_t fullset;
static int doconnect(void);
@@ -237,7 +245,7 @@
* typically we don't have a frame waiting
* when we come in here, so call kevent now
*/
- rv = host_kevent(kq, NULL, 0,
+ rv = host_kevent(holyfd, NULL, 0,
kev, __arraycount(kev), NULL);
if (__predict_false(rv == -1)) {
@@ -267,13 +275,19 @@
* determine what happens next.
*/
activity:
-#else /* USE_KQUEUE */
- struct pollfd pfd;
+#else /* !USE_KQUEUE */
+ struct pollfd pfd[2];
- pfd.fd = clispc.spc_fd;
- pfd.events = POLLIN;
+ pfd[0].fd = clispc.spc_fd;
+ pfd[0].events = POLLIN;
+ pfd[1].fd = holyfd;
+ pfd[1].events = POLLIN;
- rv = host_poll(&pfd, 1, -1);
+ rv = host_poll(pfd, 2, -1);
+ if (pfd[1].revents & POLLIN) {
+ dosig = 1;
+ goto cleanup;
+ }
#endif /* !USE_KQUEUE */
switch (readframe(spc)) {
@@ -677,6 +691,52 @@
return myfd;
}
+#if defined(USE_KQUEUE)
+
+static int
+makeholyfd(void)
+{
+ struct kevent kev[NSIG+1];
+ int i, fd;
+
+ /* setup kqueue, we want all signals and the fd */
+ if ((fd = dupgood(host_kqueue(), 0)) == -1) {
+ ERRLOG(("rump_sp: cannot setup kqueue"));
+ return -1;
+ }
+
+ for (i = 0; i < NSIG; i++) {
+ EV_SET(&kev[i], i+1, EVFILT_SIGNAL, EV_ADD|EV_ENABLE, 0, 0, 0);
+ }
+ EV_SET(&kev[NSIG], clispc.spc_fd,
+ EVFILT_READ, EV_ADD|EV_ENABLE, 0, 0, 0);
+ if (host_kevent(fd, kev, NSIG+1, NULL, 0, NULL) == -1) {
+ ERRLOG(("rump_sp: kevent() failed"));
+ return -1;
+
+ return fd;
+}
+
+#elif defined(USE_SIGNALFD) /* !USE_KQUEUE */
+
+static int
+makeholyfd(void)
+{
+
+ return host_signalfd(-1, &fullset, 0);
+}
+
+#else /* !USE_KQUEUE && !USE_SIGNALFD */
+
+static int
+makeholyfd(void)
+{
+
+ return -1;
+}
+
+#endif
+
static int
doconnect(void)
{
@@ -686,9 +746,9 @@
int s, error, flags;
ssize_t n;
- if (kq != -1)
- host_close(kq);
- kq = -1;
+ if (holyfd != -1)
+ host_close(holyfd);
+ holyfd = -1;
s = -1;
if (clispc.spc_fd != -1)
@@ -759,29 +819,7 @@
clispc.spc_fd = s;
clispc.spc_state = SPCSTATE_RUNNING;
clispc.spc_reconnecting = 0;
-
-#ifdef USE_KQUEUE
-{
- struct kevent kev[NSIG+1];
- int i;
-
- /* setup kqueue, we want all signals and the fd */
- if ((kq = dupgood(host_kqueue(), 0)) == -1) {
- ERRLOG(("rump_sp: cannot setup kqueue"));
- return -1;
- }
-
- for (i = 0; i < NSIG; i++) {
- EV_SET(&kev[i], i+1, EVFILT_SIGNAL, EV_ADD|EV_ENABLE, 0, 0, 0);
- }
- EV_SET(&kev[NSIG], clispc.spc_fd,
- EVFILT_READ, EV_ADD|EV_ENABLE, 0, 0, 0);
- if (host_kevent(kq, kev, NSIG+1, NULL, 0, NULL) == -1) {
- ERRLOG(("rump_sp: kevent() failed"));
- return -1;
- }
-}
-#endif /* USE_KQUEUE */
+ holyfd = makeholyfd();
return 0;
}
@@ -831,8 +869,10 @@
return 0;
/* kq does not traverse fork() */
+#ifdef USE_KQUEUE
if (init_done != 0)
- kq = -1;
+ holyfd = -1;
+#endif
init_done = mypid;
sigfillset(&fullset);
@@ -883,6 +923,10 @@
#endif
#endif /* USE_KQUEUE */
+#ifdef USE_SIGNALFD
+ FINDSYM(signalfd)
+#endif
+
#undef FINDSYM
#undef FINDSY2
@@ -903,7 +947,7 @@
goto out;
if ((p = getenv("RUMPCLIENT__EXECFD")) != NULL) {
- sscanf(p, "%d,%d", &clispc.spc_fd, &kq);
+ sscanf(p, "%d,%d", &clispc.spc_fd, &holyfd);
unsetenv("RUMPCLIENT__EXECFD");
hstype = HANDSHAKE_EXEC;
} else {
@@ -932,7 +976,7 @@
struct rumpclient_fork {
uint32_t fork_auth[AUTHLEN];
struct spclient fork_spc;
- int fork_kq;
+ int fork_holyfd;
};
struct rumpclient_fork *
@@ -959,7 +1003,7 @@
free(resp);
rpf->fork_spc = clispc;
- rpf->fork_kq = kq;
+ rpf->fork_holyfd = holyfd;
out:
pthread_sigmask(SIG_SETMASK, &omask, NULL);
@@ -976,7 +1020,14 @@
memset(&clispc, 0, sizeof(clispc));
clispc.spc_fd = osock;
- kq = -1; /* kqueue descriptor is not copied over fork() */
+#ifdef USE_KQUEUE
+ holyfd = -1; /* kqueue descriptor is not copied over fork() */
+#else
+ if (holyfd != -1) {
+ host_close(holyfd);
+ holyfd = -1;
+ }
+#endif
if (doinit() == -1)
return -1;
@@ -1008,7 +1059,7 @@
{
clispc = rpf->fork_spc;
- kq = rpf->fork_kq;
+ holyfd = rpf->fork_holyfd;
}
void
@@ -1030,9 +1081,9 @@
switch (variant) {
case RUMPCLIENT_CLOSE_FCLOSEM:
- untilfd = MAX(clispc.spc_fd, kq);
+ untilfd = MAX(clispc.spc_fd, holyfd);
for (; fd <= untilfd; fd++) {
- if (fd == clispc.spc_fd || fd == kq)
+ if (fd == clispc.spc_fd || fd == holyfd)
continue;
rv = host_close(fd);
if (rv == -1)
@@ -1061,23 +1112,20 @@
EVFILT_READ, EV_DELETE, 0, 0, 0);
EV_SET(&kev[1], newfd,
EVFILT_READ, EV_ADD|EV_ENABLE, 0, 0, 0);
- if (host_kevent(kq, kev, 2, NULL, 0, NULL) == -1) {
+ if (host_kevent(holyfd, kev, 2, NULL, 0, NULL) == -1) {
int sverrno = errno;
host_close(newfd);
errno = sverrno;
return -1;
- }
+ }}
+#endif /* !USE_KQUEUE */
clispc.spc_fd = newfd;
- }
}
- if (fd == kq) {
- newfd = dupgood(kq, 1);
+ if (holyfd != -1 && fd == holyfd) {
+ newfd = dupgood(holyfd, 1);
if (newfd == -1)
return -1;
- kq = newfd;
-#else /* USE_KQUEUE */
- clispc.spc_fd = newfd;
-#endif /* !USE_KQUEUE */
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