[CRIU] [PATCH] fix segmentation fault caused by uninitialized mutex

[Dengguangxing]

Segmentation fault was raised while trying to restore a process with
tty. Coredump file says this is caused by uninitialized tty_mutex:
        (gdb) where
        #0  0x00000000004d7270 in atomic_add_return (i=1, v=0x0) at
        include/common/asm/atomic.h:34
        #1  0x00000000004d7398 in mutex_lock (m=0x0) at
        include/common/lock.h:151
        #2  0x00000000004d840c in __pty_open_ptmx_index (index=3, flags=2,
        cb=0x4dce50 <open_pty>, arg=0x11, path=0x5562e0 "ptmx") at
        criu/tty.c:603
        #3  0x00000000004dced8 in pty_create_ptmx_index (dfd=17, index=3,
        flags=2) at criu/tty.c:2384

since init_tty_mutex() is reentrantable, just calling it before
mutex_lock()

Signed-off-by: Deng Guangxing <dengguangxing at huawei.com>
---
 criu/tty.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/criu/tty.c b/criu/tty.c
index 6fe11530..e9a28897 100644
--- a/criu/tty.c
+++ b/criu/tty.c
@@ -600,6 +600,9 @@ static int __pty_open_ptmx_index(int index, int flags,

        memset(fds, 0xff, sizeof(fds));

+       if (init_tty_mutex())
+               return -1;
+
        mutex_lock(tty_mutex);

        for (i = 0; i < ARRAY_SIZE(fds); i++) {
--
2.17.1