From ce3b642d42f36406112ab474c03d81c5941d9398 Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Sat, 1 Dec 2007 12:16:30 -0800 Subject: [PATCH] uml: work around host tcsetattr bug Under the conditions that UML uses it, tcgetattr is guaranteed to return -EINTR when the console is attached to /dev/ptmx, making generic_console_write hang because it loops, calling tcgetattr until it succeeds. This is a host bug - see http://marc.info/?l=linux-kernel&m=119618990807182&w=2 for the details. This patch works around it by blocking SIGIO while the terminal attributes are being fiddled. Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/drivers/chan_user.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/um/drivers/chan_user.c b/arch/um/drivers/chan_user.c index b88e93b3a3..025764089a 100644 --- a/arch/um/drivers/chan_user.c +++ b/arch/um/drivers/chan_user.c @@ -74,10 +74,16 @@ void generic_free(void *data) int generic_console_write(int fd, const char *buf, int n) { + sigset_t old, no_sigio; struct termios save, new; int err; if (isatty(fd)) { + sigemptyset(&no_sigio); + sigaddset(&no_sigio, SIGIO); + if (sigprocmask(SIG_BLOCK, &no_sigio, &old)) + goto error; + CATCH_EINTR(err = tcgetattr(fd, &save)); if (err) goto error; @@ -97,8 +103,11 @@ int generic_console_write(int fd, const char *buf, int n) * Restore raw mode, in any case; we *must* ignore any error apart * EINTR, except for debug. */ - if (isatty(fd)) + if (isatty(fd)) { CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save)); + sigprocmask(SIG_SETMASK, &old, NULL); + } + return err; error: return -errno; -- 2.39.5