Commit:     ce3b642d42f36406112ab474c03d81c5941d9398
Parent:     0a765329ed656ef08915c8be4aba9031ba467ee4
Author:     Jeff Dike <[EMAIL PROTECTED]>
AuthorDate: Sat Dec 1 12:16:30 2007 -0800
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon Dec 3 08:13:17 2007 -0800

    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 
    hang because it loops, calling tcgetattr until it succeeds.  This is a host
    bug - see for the
    This patch works around it by blocking SIGIO while the terminal attributes 
    being fiddled.
    Signed-off-by: Jeff Dike <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 arch/um/drivers/chan_user.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/arch/um/drivers/chan_user.c b/arch/um/drivers/chan_user.c
index b88e93b..0257640 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;
        return -errno;
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