On 2011-12-08 04:48, Michael Roth wrote:
> This patch fixes a bug where child processes of launch_script() can
> misbehave due to SIGCHLD being blocked. In the case of `sudo`, this
> causes a permanent hang.
>
> Previously a SIGCHLD handler was added to reap fork_exec()'d zombie
> processes by calling waitpid(-1, ...). This required other
> fork()/waitpid() callers to temporarilly block SIGCHILD to avoid
> having the final wait status being intercepted by the SIGCHLD
> handler:
>
> 7c3370d4fe3fa6cda8655f109e4659afc8ca4269
>
> Since then, the qemu_add_child_watch() interface was added to allow
> registration of such processes and reap only from that specific set
> of PIDs:
>
> 4d54ec7898bd951007cb6122d5315584bd41d0c4
>
> As a result, we can now avoid blocking SIGCHLD in launch_script(), so
> drop that behavior.
>
> Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com>
> ---
> net/tap.c | 6 ------
> 1 files changed, 0 insertions(+), 6 deletions(-)
>
> diff --git a/net/tap.c b/net/tap.c
> index 1f26dc9..6c27a94 100644
> --- a/net/tap.c
> +++ b/net/tap.c
> @@ -346,15 +346,10 @@ static TAPState *net_tap_fd_init(VLANState *vlan,
>
> static int launch_script(const char *setup_script, const char *ifname, int
> fd)
> {
> - sigset_t oldmask, mask;
> int pid, status;
> char *args[3];
> char **parg;
>
> - sigemptyset(&mask);
> - sigaddset(&mask, SIGCHLD);
> - sigprocmask(SIG_BLOCK, &mask, &oldmask);
> -
> /* try to launch network script */
> pid = fork();
> if (pid == 0) {
> @@ -378,7 +373,6 @@ static int launch_script(const char *setup_script, const
> char *ifname, int fd)
> while (waitpid(pid, &status, 0) != pid) {
> /* loop */
> }
> - sigprocmask(SIG_SETMASK, &oldmask, NULL);
>
> if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
> return 0;
Looks sane.
Reviewed-by: Jan Kiszka <jan.kis...@siemens.com>
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
