On 09/25/2015 06:53 AM, Jeff Layton wrote:
> On Wed, 23 Sep 2015 17:20:50 -0400
> Steve Dickson <steved@xxxxxxxxxx> wrote:
>
>> Instead of waiting on every fork, which would
>> become a bottle neck during a mount storm, simply
>> set a SIGCHLD signal handler to do the wait on
>> the child process
>>
>> Signed-off-by: Steve Dickson <steved@xxxxxxxxxx>
>> ---
>> utils/gssd/gssd.c | 18 ++++++++++++++++++
>> utils/gssd/gssd_proc.c | 11 ++---------
>> 2 files changed, 20 insertions(+), 9 deletions(-)
>>
>> diff --git a/utils/gssd/gssd.c b/utils/gssd/gssd.c
>> index e480349..8b778cb 100644
>> --- a/utils/gssd/gssd.c
>> +++ b/utils/gssd/gssd.c
>> @@ -44,11 +44,13 @@
>> #define _GNU_SOURCE
>> #endif
>>
>> +#include <sys/types.h>
>> #include <sys/param.h>
>> #include <sys/socket.h>
>> #include <sys/time.h>
>> #include <sys/resource.h>
>> #include <sys/inotify.h>
>> +#include <sys/wait.h>
>> #include <rpc/rpc.h>
>> #include <netinet/in.h>
>> #include <arpa/inet.h>
>> @@ -736,6 +738,21 @@ sig_die(int signal)
>> printerr(1, "exiting on signal %d\n", signal);
>> exit(0);
>> }
>> +static void
>> +sig_child(int signal)
>> +{
>> + int err;
>> + pid_t pid;
>> +
>> + /* Parent: just wait on child to exit and return */
>> + do {
>> + pid = wait(&err);
>> + } while(pid == -1 && errno != -ECHILD);
>> +
>> + if (WIFSIGNALED(err))
>> + printerr(0, "WARNING: forked child was killed"
>> + "with signal %d\n", WTERMSIG(err));
>> +}
>>
>> static void
>> usage(char *progname)
>> @@ -902,6 +919,7 @@ main(int argc, char *argv[])
>>
>> signal(SIGINT, sig_die);
>> signal(SIGTERM, sig_die);
>> + signal(SIGCHLD, sig_child);
>> signal_set(&sighup_ev, SIGHUP, gssd_scan_cb, NULL);
>> signal_add(&sighup_ev, NULL);
>> event_set(&inotify_ev, inotify_fd, EV_READ | EV_PERSIST, gssd_inotify_cb, NULL);
>> diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
>> index 11168b2..8f5ca03 100644
>> --- a/utils/gssd/gssd_proc.c
>> +++ b/utils/gssd/gssd_proc.c
>> @@ -656,16 +656,9 @@ process_krb5_upcall(struct clnt_info *clp, uid_t uid, int fd, char *tgtname,
>> /* fork() failed! */
>> printerr(0, "WARNING: unable to fork() to handle"
>> "upcall: %s\n", strerror(errno));
>> - return;
>> + /* FALLTHROUGH */
>> default:
>> - /* Parent: just wait on child to exit and return */
>> - do {
>> - pid = wait(&err);
>> - } while(pid == -1 && errno != -ECHILD);
>> -
>> - if (WIFSIGNALED(err))
>> - printerr(0, "WARNING: forked child was killed"
>> - "with signal %d\n", WTERMSIG(err));
>> + /* Parent: Return and wait for the SIGCHLD */
>> return;
>> }
>> no_fork:
>
> I was thinking that there was some reason that we couldn't do this --
> that there were data structures that would get wiped if you got another
> upcall while the first was being processed. The forking should prevent
> that though, so I think this looks reasonable.
>
> Acked-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
>
Self Nak... During my testing there was a large number zombie rpc.gssd
process... I'm not sure why but they are there...
steved.
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