X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fum%2Fdrivers%2Fchan_user.c;h=0cad3546cb8922a013893d516111f9f669115fdb;hb=97bf2856c6014879bd04983a3e9dfcdac1e7fe85;hp=8a5180a779e57bb7e1d11598ee51945bb9022c3c;hpb=c7b5ebbddf7bcd3651947760f423e3783bbe6573;p=linux-2.6.git diff --git a/arch/um/drivers/chan_user.c b/arch/um/drivers/chan_user.c index 8a5180a77..0cad3546c 100644 --- a/arch/um/drivers/chan_user.c +++ b/arch/um/drivers/chan_user.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -16,27 +17,56 @@ #include "user_util.h" #include "chan_user.h" #include "user.h" -#include "helper.h" #include "os.h" #include "choose-mode.h" #include "mode.h" -int generic_console_write(int fd, const char *buf, int n, void *unused) +int generic_console_write(int fd, const char *buf, int n) { struct termios save, new; int err; if(isatty(fd)){ - tcgetattr(fd, &save); + CATCH_EINTR(err = tcgetattr(fd, &save)); + if (err) + goto error; new = save; + /* The terminal becomes a bit less raw, to handle \n also as + * "Carriage Return", not only as "New Line". Otherwise, the new + * line won't start at the first column.*/ new.c_oflag |= OPOST; - tcsetattr(fd, TCSAFLUSH, &new); + CATCH_EINTR(err = tcsetattr(fd, TCSAFLUSH, &new)); + if (err) + goto error; } err = generic_write(fd, buf, n, NULL); - if(isatty(fd)) tcsetattr(fd, TCSAFLUSH, &save); + /* Restore raw mode, in any case; we *must* ignore any error apart + * EINTR, except for debug.*/ + if(isatty(fd)) + CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save)); return(err); +error: + return(-errno); } +/* + * UML SIGWINCH handling + * + * The point of this is to handle SIGWINCH on consoles which have host ttys and + * relay them inside UML to whatever might be running on the console and cares + * about the window size (since SIGWINCH notifies about terminal size changes). + * + * So, we have a separate thread for each host tty attached to a UML device + * (side-issue - I'm annoyed that one thread can't have multiple controlling + * ttys for purposed of handling SIGWINCH, but I imagine there are other reasons + * that doesn't make any sense). + * + * SIGWINCH can't be received synchronously, so you have to set up to receive it + * as a signal. That being the case, if you are going to wait for it, it is + * convenient to sit in sigsuspend() and wait for the signal to bounce you out of + * it (see below for how we make sure to exit only on SIGWINCH). + */ + static void winch_handler(int sig) { } @@ -44,7 +74,6 @@ static void winch_handler(int sig) struct winch_data { int pty_fd; int pipe_fd; - int close_me; }; static int winch_thread(void *arg) @@ -55,7 +84,6 @@ static int winch_thread(void *arg) int count, err; char c = 1; - os_close_file(data->close_me); pty_fd = data->pty_fd; pipe_fd = data->pipe_fd; count = os_write_file(pipe_fd, &c, sizeof(c)); @@ -63,14 +91,20 @@ static int winch_thread(void *arg) printk("winch_thread : failed to write synchronization " "byte, err = %d\n", -count); + /* We are not using SIG_IGN on purpose, so don't fix it as I thought to + * do! If using SIG_IGN, the sigsuspend() call below would not stop on + * SIGWINCH. */ + signal(SIGWINCH, winch_handler); sigfillset(&sigs); - sigdelset(&sigs, SIGWINCH); + /* Block all signals possible. */ if(sigprocmask(SIG_SETMASK, &sigs, NULL) < 0){ printk("winch_thread : sigprocmask failed, errno = %d\n", errno); exit(1); } + /* In sigsuspend(), block anything else than SIGWINCH. */ + sigdelset(&sigs, SIGWINCH); if(setsid() < 0){ printk("winch_thread : setsid failed, errno = %d\n", errno); @@ -83,13 +117,19 @@ static int winch_thread(void *arg) exit(1); } + /* These are synchronization calls between various UML threads on the + * host - since they are not different kernel threads, we cannot use + * kernel semaphores. We don't use SysV semaphores because they are + * persistent. */ count = os_read_file(pipe_fd, &c, sizeof(c)); if(count != sizeof(c)) printk("winch_thread : failed to read synchronization byte, " "err = %d\n", -count); while(1){ - pause(); + /* This will be interrupted by SIGWINCH only, since other signals + * are blocked.*/ + sigsuspend(&sigs); count = os_write_file(pipe_fd, &c, sizeof(c)); if(count != sizeof(c)) @@ -98,43 +138,51 @@ static int winch_thread(void *arg) } } -static int winch_tramp(int fd, void *device_data, int *fd_out) +static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out) { struct winch_data data; unsigned long stack; - int fds[2], pid, n, err; + int fds[2], n, err; char c; err = os_pipe(fds, 1, 1); if(err < 0){ printk("winch_tramp : os_pipe failed, err = %d\n", -err); - return(err); + goto out; } data = ((struct winch_data) { .pty_fd = fd, - .pipe_fd = fds[1], - .close_me = fds[0] } ); - pid = run_helper_thread(winch_thread, &data, 0, &stack, 0); - if(pid < 0){ + .pipe_fd = fds[1] } ); + /* CLONE_FILES so this thread doesn't hold open files which are open + * now, but later closed. This is a problem with /dev/net/tun. + */ + err = run_helper_thread(winch_thread, &data, CLONE_FILES, &stack, 0); + if(err < 0){ printk("fork of winch_thread failed - errno = %d\n", errno); - return(pid); + goto out_close; } - os_close_file(fds[1]); *fd_out = fds[0]; n = os_read_file(fds[0], &c, sizeof(c)); if(n != sizeof(c)){ printk("winch_tramp : failed to read synchronization byte\n"); printk("read failed, err = %d\n", -n); printk("fd %d will not support SIGWINCH\n", fd); - *fd_out = -1; + err = -EINVAL; + goto out_close; } - return(pid); + return err ; + + out_close: + os_close_file(fds[1]); + os_close_file(fds[0]); + out: + return err; } -void register_winch(int fd, void *device_data) +void register_winch(int fd, struct tty_struct *tty) { - int pid, thread, thread_fd; + int pid, thread, thread_fd = -1; int count; char c = 1; @@ -143,10 +191,10 @@ void register_winch(int fd, void *device_data) pid = tcgetpgrp(fd); if(!CHOOSE_MODE_PROC(is_tracer_winch, is_skas_winch, pid, fd, - device_data) && (pid == -1)){ - thread = winch_tramp(fd, device_data, &thread_fd); - if(fd != -1){ - register_winch_irq(thread_fd, fd, thread, device_data); + tty) && (pid == -1)){ + thread = winch_tramp(fd, tty, &thread_fd); + if(thread > 0){ + register_winch_irq(thread_fd, fd, thread, tty); count = os_write_file(thread_fd, &c, sizeof(c)); if(count != sizeof(c))