From: Stanislaw Gruszka Date: Tue, 18 Dec 2007 00:19:46 +0000 (-0800) Subject: uml: stop gdb from deleting breakpoints when running UML X-Git-Tag: v2.6.24-rc6~53 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4dbed85a35ed37d9608f4f32e5d69efa775d6223;p=linux-2.6 uml: stop gdb from deleting breakpoints when running UML 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 Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/um/drivers/net_user.c b/arch/um/drivers/net_user.c index 90d7f2e8ea..29185cad9f 100644 --- a/arch/um/drivers/net_user.c +++ b/arch/um/drivers/net_user.c @@ -201,7 +201,7 @@ static int change_tramp(char **argv, char *output, int output_len) close(fds[1]); if (pid > 0) - CATCH_EINTR(err = waitpid(pid, NULL, 0)); + helper_wait(pid, 0, "change_tramp"); return pid; } diff --git a/arch/um/drivers/slip_user.c b/arch/um/drivers/slip_user.c index 5f06204d68..b8711e50da 100644 --- a/arch/um/drivers/slip_user.c +++ b/arch/um/drivers/slip_user.c @@ -77,7 +77,7 @@ static int slip_tramp(char **argv, int fd) { struct slip_pre_exec_data pe_data; char *output; - int status, pid, fds[2], err, output_len; + int pid, fds[2], err, output_len; err = os_pipe(fds, 1, 0); if (err < 0) { @@ -109,15 +109,7 @@ static int slip_tramp(char **argv, int fd) read_output(fds[0], output, output_len); printk("%s", output); - CATCH_EINTR(err = waitpid(pid, &status, 0)); - if (err < 0) - err = errno; - else if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0)) { - printk(UM_KERN_ERR "'%s' didn't exit with status 0\n", argv[0]); - err = -EINVAL; - } - else err = 0; - + err = helper_wait(pid, 0, argv[0]); close(fds[0]); out_free: diff --git a/arch/um/drivers/slirp_user.c b/arch/um/drivers/slirp_user.c index 1865089ff4..89c1be225f 100644 --- a/arch/um/drivers/slirp_user.c +++ b/arch/um/drivers/slirp_user.c @@ -79,7 +79,7 @@ out: static void slirp_close(int fd, void *data) { struct slirp_data *pri = data; - int status,err; + int err; close(fd); close(pri->slave); @@ -98,18 +98,9 @@ static void slirp_close(int fd, void *data) "(%d)\n", pri->pid, errno); } #endif - - CATCH_EINTR(err = waitpid(pri->pid, &status, WNOHANG)); - if (err < 0) { - printk(UM_KERN_ERR "slirp_close: waitpid returned %d\n", errno); - return; - } - - if (err == 0) { - printk(UM_KERN_ERR "slirp_close: process %d has not exited\n", - pri->pid); + err = helper_wait(pri->pid, 1, "slirp_close"); + if (err < 0) return; - } pri->pid = -1; } diff --git a/arch/um/drivers/ubd_user.c b/arch/um/drivers/ubd_user.c index 41d254bd38..48fc7452bc 100644 --- a/arch/um/drivers/ubd_user.c +++ b/arch/um/drivers/ubd_user.c @@ -49,8 +49,7 @@ int start_io_thread(unsigned long sp, int *fd_out) goto out_close; } - pid = clone(io_thread, (void *) sp, CLONE_FILES | CLONE_VM | SIGCHLD, - NULL); + pid = clone(io_thread, (void *) sp, CLONE_FILES | CLONE_VM, NULL); if(pid < 0){ err = -errno; printk("start_io_thread - clone failed : errno = %d\n", errno); diff --git a/arch/um/include/os.h b/arch/um/include/os.h index fbf0a87c6e..6f0d1c741b 100644 --- a/arch/um/include/os.h +++ b/arch/um/include/os.h @@ -214,7 +214,7 @@ extern int execvp_noalloc(char *buf, const char *file, char *const argv[]); extern int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv); extern int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, unsigned long *stack_out); -extern int helper_wait(int pid); +extern int helper_wait(int pid, int nohang, char *pname); /* tls.c */ diff --git a/arch/um/os-Linux/aio.c b/arch/um/os-Linux/aio.c index 4158118c4a..93dc0c80eb 100644 --- a/arch/um/os-Linux/aio.c +++ b/arch/um/os-Linux/aio.c @@ -218,7 +218,7 @@ static int init_aio_24(void) goto out_close_pipe; err = run_helper_thread(not_aio_thread, NULL, - CLONE_FILES | CLONE_VM | SIGCHLD, &aio_stack); + CLONE_FILES | CLONE_VM, &aio_stack); if (err < 0) goto out_close_pipe; @@ -254,7 +254,7 @@ static int init_aio_26(void) } err = run_helper_thread(aio_thread, NULL, - CLONE_FILES | CLONE_VM | SIGCHLD, &aio_stack); + CLONE_FILES | CLONE_VM, &aio_stack); if (err < 0) return err; diff --git a/arch/um/os-Linux/drivers/ethertap_user.c b/arch/um/os-Linux/drivers/ethertap_user.c index 4ff5536034..07ca0cb472 100644 --- a/arch/um/os-Linux/drivers/ethertap_user.c +++ b/arch/um/os-Linux/drivers/ethertap_user.c @@ -94,7 +94,7 @@ static int etap_tramp(char *dev, char *gate, int control_me, int control_remote, int data_me, int data_remote) { struct etap_pre_exec_data pe_data; - int pid, status, err, n; + int pid, err, n; char version_buf[sizeof("nnnnn\0")]; char data_fd_buf[sizeof("nnnnnn\0")]; char gate_buf[sizeof("nnn.nnn.nnn.nnn\0")]; @@ -131,13 +131,7 @@ static int etap_tramp(char *dev, char *gate, int control_me, } if (c != 1) { printk(UM_KERN_ERR "etap_tramp : uml_net failed\n"); - err = -EINVAL; - CATCH_EINTR(n = waitpid(pid, &status, 0)); - if (n < 0) - err = -errno; - else if (!WIFEXITED(status) || (WEXITSTATUS(status) != 1)) - printk(UM_KERN_ERR "uml_net didn't exit with " - "status 1\n"); + err = helper_wait(pid, 0, "uml_net"); } return err; } diff --git a/arch/um/os-Linux/drivers/tuntap_user.c b/arch/um/os-Linux/drivers/tuntap_user.c index 6c55d3c8ea..1037a3b638 100644 --- a/arch/um/os-Linux/drivers/tuntap_user.c +++ b/arch/um/os-Linux/drivers/tuntap_user.c @@ -107,7 +107,7 @@ static int tuntap_open_tramp(char *gate, int *fd_out, int me, int remote, "errno = %d\n", errno); return err; } - CATCH_EINTR(waitpid(pid, NULL, 0)); + helper_wait(pid, 0, "tuntap_open_tramp"); cmsg = CMSG_FIRSTHDR(&msg); if (cmsg == NULL) { diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c index 7a72dbb61b..fba3f0fefe 100644 --- a/arch/um/os-Linux/helper.c +++ b/arch/um/os-Linux/helper.c @@ -76,7 +76,7 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv) data.fd = fds[1]; data.buf = __cant_sleep() ? kmalloc(PATH_MAX, UM_GFP_ATOMIC) : kmalloc(PATH_MAX, UM_GFP_KERNEL); - pid = clone(helper_child, (void *) sp, CLONE_VM | SIGCHLD, &data); + pid = clone(helper_child, (void *) sp, CLONE_VM, &data); if (pid < 0) { ret = -errno; printk("run_helper : clone failed, errno = %d\n", errno); @@ -101,7 +101,7 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv) ret = n; kill(pid, SIGKILL); } - CATCH_EINTR(waitpid(pid, NULL, 0)); + CATCH_EINTR(waitpid(pid, NULL, __WCLONE)); } out_free2: @@ -126,7 +126,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, return -ENOMEM; sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *); - pid = clone(proc, (void *) sp, flags | SIGCHLD, arg); + pid = clone(proc, (void *) sp, flags, arg); if (pid < 0) { err = -errno; printk("run_helper_thread : clone failed, errno = %d\n", @@ -134,7 +134,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, return err; } if (stack_out == NULL) { - CATCH_EINTR(pid = waitpid(pid, &status, 0)); + CATCH_EINTR(pid = waitpid(pid, &status, __WCLONE)); if (pid < 0) { err = -errno; printk("run_helper_thread - wait failed, errno = %d\n", @@ -150,14 +150,30 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags, return pid; } -int helper_wait(int pid) +int helper_wait(int pid, int nohang, char *pname) { - int ret; + int ret, status; + int wflags = __WCLONE; - CATCH_EINTR(ret = waitpid(pid, NULL, WNOHANG)); + if (nohang) + wflags |= WNOHANG; + + if (!pname) + pname = "helper_wait"; + + CATCH_EINTR(ret = waitpid(pid, &status, wflags)); if (ret < 0) { - ret = -errno; - printk("helper_wait : waitpid failed, errno = %d\n", errno); - } - return ret; + printk(UM_KERN_ERR "%s : waitpid process %d failed, " + "errno = %d\n", pname, pid, errno); + return -errno; + } else if (nohang && ret == 0) { + printk(UM_KERN_ERR "%s : process %d has not exited\n", + pname, pid); + return -ECHILD; + } else if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { + printk(UM_KERN_ERR "%s : process %d didn't exit with " + "status 0\n", pname, pid); + return -ECHILD; + } else + return 0; } diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c index 37781db4ce..bda5c3150d 100644 --- a/arch/um/os-Linux/process.c +++ b/arch/um/os-Linux/process.c @@ -101,7 +101,7 @@ void os_kill_process(int pid, int reap_child) { kill(pid, SIGKILL); if (reap_child) - CATCH_EINTR(waitpid(pid, NULL, 0)); + CATCH_EINTR(waitpid(pid, NULL, __WALL)); } /* This is here uniquely to have access to the userspace errno, i.e. the one @@ -130,7 +130,7 @@ void os_kill_ptraced_process(int pid, int reap_child) ptrace(PTRACE_KILL, pid); ptrace(PTRACE_CONT, pid); if (reap_child) - CATCH_EINTR(waitpid(pid, NULL, 0)); + CATCH_EINTR(waitpid(pid, NULL, __WALL)); } /* Don't use the glibc version, which caches the result in TLS. It misses some diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c index d77c81d706..e8b7a97e83 100644 --- a/arch/um/os-Linux/skas/process.c +++ b/arch/um/os-Linux/skas/process.c @@ -64,7 +64,7 @@ void wait_stub_done(int pid) int n, status, err; while (1) { - CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); + CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL)); if ((n < 0) || !WIFSTOPPED(status)) goto bad_wait; @@ -153,7 +153,7 @@ static void handle_trap(int pid, struct uml_pt_regs *regs, panic("handle_trap - continuing to end of syscall " "failed, errno = %d\n", errno); - CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED)); + CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL)); if ((err < 0) || !WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP + 0x80)) { err = ptrace_dump_regs(pid); @@ -255,16 +255,18 @@ int start_userspace(unsigned long stub_stack) panic("start_userspace : mmap failed, errno = %d", errno); sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *); - flags = CLONE_FILES | SIGCHLD; + flags = CLONE_FILES; if (proc_mm) flags |= CLONE_VM; + else + flags |= SIGCHLD; pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack); if (pid < 0) panic("start_userspace : clone failed, errno = %d", errno); do { - CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED)); + CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL)); if (n < 0) panic("start_userspace : wait failed, errno = %d", errno); @@ -314,7 +316,7 @@ void userspace(struct uml_pt_regs *regs) "pid=%d, ptrace operation = %d, errno = %d\n", pid, op, errno); - CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED)); + CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL)); if (err < 0) panic("userspace - waitpid failed, errno = %d\n", errno); diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c index ef095436a7..3e058ce9ff 100644 --- a/arch/um/os-Linux/util.c +++ b/arch/um/os-Linux/util.c @@ -141,7 +141,7 @@ void os_dump_core(void) * nothing reasonable to do if that fails. */ - while ((pid = waitpid(-1, NULL, WNOHANG)) > 0) + while ((pid = waitpid(-1, NULL, WNOHANG | __WALL)) > 0) os_kill_ptraced_process(pid, 0); abort();