Add a regression test to detect if waiting on the I/O serialization lock
on socket buffers is interruptible or not, which detacts the regression I introduced recently in 7-CURRENT (spotted by alfred). This test passes in older -CURRENT, and with the as-yet uncommitted sx_xlock_sig and sblock fix patches.
This commit is contained in:
rwatson
parent
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7b2a47f768
9
tools/regression/sockets/sblock/Makefile
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9
tools/regression/sockets/sblock/Makefile
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#
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# $FreeBSD$
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#
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PROG= sblock
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NO_MAN=
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WARNS?= 2
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.include <bsd.prog.mk>
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207
tools/regression/sockets/sblock/sblock.c
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207
tools/regression/sockets/sblock/sblock.c
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/*-
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* Copyright (c) 2007 Robert N. M. Watson
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* Sockets serialize I/O in each direction in order to avoid interlacing of
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* I/O by multiple processes or threcvs recving or sending the socket. This
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* is done using some form of kernel lock (varies by kernel version), called
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* "sblock" in FreeBSD. However, to avoid unkillable processes waiting on
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* I/O that may be entirely controlled by a remote network endpoint, that
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* lock acquisition must be interruptible.
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*
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* To test this, set up a local domain stream socket pair and a set of three
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* processes. Two processes block in recv(), the first on sbwait (wait for
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* I/O), and the second on the sblock waiting for the first to finish. A
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* third process is responsible for signalling the second process, then
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* writing to the socket. Depending on the error returned in the second
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* process, we can tell whether the sblock wait was interrupted, or if
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* instead the process only woke up when the write was performed.
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*/
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#include <sys/socket.h>
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#include <err.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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static int interrupted;
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static void
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signal_handler(int signum)
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{
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interrupted++;
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}
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/*
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* Process that will perform a blocking recv on a UNIX domain socket. This
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* should return one byte of data.
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*/
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static void
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blocking_recver(int fd)
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{
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ssize_t len;
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char ch;
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len = recv(fd, &ch, sizeof(ch), 0);
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if (len < 0)
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err(-1, "FAIL: blocking_recver: recv");
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if (len == 0)
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errx(-1, "FAIL: blocking_recver: recv: eof");
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if (len != 1)
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errx(-1, "FAIL: blocking_recver: recv: %d bytes", len);
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if (interrupted)
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errx(-1, "FAIL: blocking_recver: interrupted wrong pid");
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}
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/*
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* Process that will perform a locking recv on a UNIX domain socket.
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*
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* This is where we figure out if the test worked or not. If it has failed,
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* then recv() will return EOF, as the close() arrives before the signal,
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* meaning that the wait for the sblock was not interrupted; if it has
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* succeeded, we get EINTR as the signal interrupts the lock request.
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*/
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static void
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locking_recver(int fd)
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{
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ssize_t len;
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char ch;
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if (sleep(1) < 0)
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err(-1, "FAIL: locking_recver: sleep");
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len = recv(fd, &ch, sizeof(ch), 0);
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if (len < 0 && errno != EINTR)
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err(-1, "FAIL: locking_recver: recv");
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if (len < 0 && errno == EINTR) {
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fprintf(stderr, "PASS\n");
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exit(0);
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}
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if (len == 0)
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errx(-1, "FAIL: locking_recver: recv: eof");
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if (!interrupted)
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errx(-1, "FAIL: locking_recver: not interrupted");
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}
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static void
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signaller(pid_t locking_recver_pid, int fd)
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{
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ssize_t len;
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char ch;
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if (sleep(2) < 0) {
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warn("signaller sleep(2)");
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return;
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}
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if (kill(locking_recver_pid, SIGHUP) < 0) {
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warn("signaller kill(%d)", locking_recver_pid);
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return;
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}
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if (sleep(1) < 0) {
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warn("signaller sleep(1)");
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return;
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}
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len = send(fd, &ch, sizeof(ch), 0);
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if (len < 0) {
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warn("signaller send");
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return;
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}
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if (len != sizeof(ch)) {
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warnx("signaller send ret %d", len);
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return;
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}
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if (close(fd) < 0) {
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warn("signaller close");
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return;
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}
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if (sleep(1) < 0) {
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warn("signaller sleep(1)");
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return;
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}
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}
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int
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main(int argc, char *argv[])
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{
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int error, fds[2], recver_fd, sender_fd;
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pid_t blocking_recver_pid;
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pid_t locking_recver_pid;
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struct sigaction sa;
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if (sigaction(SIGHUP, NULL, &sa) < 0)
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err(-1, "FAIL: sigaction(SIGHUP, NULL, &sa)");
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sa.sa_handler = signal_handler;
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if (sa.sa_flags & SA_RESTART)
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printf("SIGHUP restartable by default (cleared)\n");
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sa.sa_flags &= ~SA_RESTART;
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if (sigaction(SIGHUP, &sa, NULL) < 0)
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err(-1, "FAIL: sigaction(SIGHUP, &sa, NULL)");
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#if 0
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if (signal(SIGHUP, signal_handler) == SIG_ERR)
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err(-1, "FAIL: signal(SIGHUP)");
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#endif
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if (socketpair(PF_LOCAL, SOCK_STREAM, 0, fds) < 0)
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err(-1, "FAIL: socketpair(PF_LOCAL, SOGK_STREAM, 0)");
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sender_fd = fds[0];
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recver_fd = fds[1];
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blocking_recver_pid = fork();
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if (blocking_recver_pid < 0)
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err(-1, "FAIL: fork");
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if (blocking_recver_pid == 0) {
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close(sender_fd);
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blocking_recver(recver_fd);
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exit(0);
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}
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locking_recver_pid = fork();
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if (locking_recver_pid < 0) {
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error = errno;
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kill(blocking_recver_pid, SIGKILL);
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errno = error;
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err(-1, "FAIL: fork");
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}
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if (locking_recver_pid == 0) {
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close(sender_fd);
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locking_recver(recver_fd);
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exit(0);
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}
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signaller(locking_recver_pid, sender_fd);
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kill(blocking_recver_pid, SIGKILL);
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kill(locking_recver_pid, SIGKILL);
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exit(0);
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}
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