4dbed85a35
Sometimes when UML is debugged gdb miss breakpoints. When process traced by gdb do fork, debugger remove breakpoints from child address space. There is possibility to trace more than one fork, but this not work with UML, I guess (only guess) there is a deadlock - gdb waits for UML and UML waits for gdb. When clone() is called with SIGCHLD and CLONE_VM flags, gdb see this as PTRACE_EVENT_FORK not as PTRACE_EVENT_CLONE and remove breakpoints from child and at the same time from traced process, because either have the same address space. Maybe it is possible to do fix in gdb, but I'm not sure if there is easy way to find out if traced and child processes share memory. So I do fix for UML, it simply do not call clone() with both SIGCHLD and CLONE_VM flags together. Additionally __WALL flag is used for waitpid() to assure not miss clone and normal process events. [ jdike - checkpatch fixes ] Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl> Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
127 lines
2.2 KiB
C
127 lines
2.2 KiB
C
/*
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* Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Licensed under the GPL.
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*/
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#include <unistd.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/wait.h>
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#include "kern_constants.h"
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#include "net_user.h"
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#include "os.h"
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#include "slirp.h"
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#include "user.h"
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static int slirp_user_init(void *data, void *dev)
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{
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struct slirp_data *pri = data;
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pri->dev = dev;
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return 0;
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}
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struct slirp_pre_exec_data {
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int stdin;
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int stdout;
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};
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static void slirp_pre_exec(void *arg)
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{
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struct slirp_pre_exec_data *data = arg;
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if (data->stdin != -1)
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dup2(data->stdin, 0);
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if (data->stdout != -1)
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dup2(data->stdout, 1);
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}
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static int slirp_tramp(char **argv, int fd)
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{
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struct slirp_pre_exec_data pe_data;
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int pid;
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pe_data.stdin = fd;
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pe_data.stdout = fd;
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pid = run_helper(slirp_pre_exec, &pe_data, argv);
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return pid;
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}
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static int slirp_open(void *data)
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{
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struct slirp_data *pri = data;
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int fds[2], pid, err;
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err = os_pipe(fds, 1, 1);
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if (err)
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return err;
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err = slirp_tramp(pri->argw.argv, fds[1]);
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if (err < 0) {
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printk(UM_KERN_ERR "slirp_tramp failed - errno = %d\n", -err);
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goto out;
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}
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pid = err;
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pri->slave = fds[1];
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pri->slip.pos = 0;
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pri->slip.esc = 0;
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pri->pid = err;
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return fds[0];
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out:
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close(fds[0]);
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close(fds[1]);
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return err;
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}
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static void slirp_close(int fd, void *data)
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{
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struct slirp_data *pri = data;
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int err;
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close(fd);
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close(pri->slave);
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pri->slave = -1;
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if (pri->pid<1) {
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printk(UM_KERN_ERR "slirp_close: no child process to shut "
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"down\n");
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return;
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}
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#if 0
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if (kill(pri->pid, SIGHUP)<0) {
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printk(UM_KERN_ERR "slirp_close: sending hangup to %d failed "
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"(%d)\n", pri->pid, errno);
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}
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#endif
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err = helper_wait(pri->pid, 1, "slirp_close");
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if (err < 0)
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return;
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pri->pid = -1;
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}
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int slirp_user_read(int fd, void *buf, int len, struct slirp_data *pri)
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{
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return slip_proto_read(fd, buf, len, &pri->slip);
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}
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int slirp_user_write(int fd, void *buf, int len, struct slirp_data *pri)
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{
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return slip_proto_write(fd, buf, len, &pri->slip);
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}
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const struct net_user_info slirp_user_info = {
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.init = slirp_user_init,
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.open = slirp_open,
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.close = slirp_close,
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.remove = NULL,
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.add_address = NULL,
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.delete_address = NULL,
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.mtu = BUF_SIZE,
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.max_packet = BUF_SIZE,
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};
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