Commit 7c3370d4 authored by Jan Kiszka's avatar Jan Kiszka Committed by Mark McLoughlin
Browse files

slirp: Avoid zombie processes after fork_exec 



Slirp uses fork_exec for spawning service processes, and QEMU uses this
for running smbd. As SIGCHLD is not handled, these processes become
zombies on termination. Fix this by installing a proper signal handler,
but also make sure we disable the signal while waiting on forked network
setup/shutdown scripts.

Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarMark McLoughlin <markmc@redhat.com>
parent c27ff608

net.c

+34 −26
Original line number Diff line number Diff line
@@ -1134,38 +1134,46 @@ static int tap_open(char *ifname, int ifname_size) 


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) {

    if (pid == 0) {

        int open_max = sysconf(_SC_OPEN_MAX), i;

                for (i = 0; i < open_max; i++)



        for (i = 0; i < open_max; i++) {

            if (i != STDIN_FILENO &&

                i != STDOUT_FILENO &&

                i != STDERR_FILENO &&

                        i != fd)

                i != fd) {

                close(i);



            }

        }

        parg = args;

        *parg++ = (char *)setup_script;

        *parg++ = (char *)ifname;

        *parg++ = NULL;

        execv(setup_script, args);

        _exit(1);

    } else if (pid > 0) {

        while (waitpid(pid, &status, 0) != pid) {

            /* loop */

        }

            while (waitpid(pid, &status, 0) != pid);

            if (!WIFEXITED(status) ||

                WEXITSTATUS(status) != 0) {

                fprintf(stderr, "%s: could not launch network script\n",

                        setup_script);

                return -1;

        sigprocmask(SIG_SETMASK, &oldmask, NULL);



        if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {

            return 0;

        }

    }

    return 0;

    fprintf(stderr, "%s: could not launch network script\n", setup_script);

    return -1;

}



static int net_tap_init(VLANState *vlan, const char *model,

vl.c

+11 −2
Original line number Diff line number Diff line
@@ -4783,7 +4783,12 @@ static void termsig_handler(int signal) 
    qemu_system_shutdown_request();

}



static void termsig_setup(void)

static void sigchld_handler(int signal)

{

    waitpid(-1, NULL, WNOHANG);

}



static void sighandler_setup(void)

{

    struct sigaction act;
@@ -4792,6 +4797,10 @@ static void termsig_setup(void) 
    sigaction(SIGINT,  &act, NULL);

    sigaction(SIGHUP,  &act, NULL);

    sigaction(SIGTERM, &act, NULL);



    act.sa_handler = sigchld_handler;

    act.sa_flags = SA_NOCLDSTOP;

    sigaction(SIGCHLD, &act, NULL);

}



#endif
@@ -5918,7 +5927,7 @@ int main(int argc, char **argv, char **envp) 


#ifndef _WIN32

    /* must be after terminal init, SDL library changes signal handlers */

    termsig_setup();

    sighandler_setup();

#endif



    /* Maintain compatibility with multiple stdio monitors */