On Fri, Jun 13, 2014 at 05:49:24PM +0200, Tom Gundersen wrote: > On Fri, Jun 13, 2014 at 4:41 PM, Werner Fink <wer...@suse.de> wrote: > > From: Ruediger Oertel <r...@suse.de> > > > > Process 1 (aka init) needs to be started with an empty signal mask. > > That includes the process 1 that's started after the initrd is finished. > > When the initrd is using systemd (as it does with dracut based initrds) > > then it is systemd that calls the real init. Normally this is systemd > > again, except when the user uses for instance "init=/bin/bash" on the > > kernel command line. > > Why is this necessary for /bin/bash, but not for /lib/systemd/systemd? > Please include the explanation in the commit message.
I do not understand your question. AFAIK the signal mask is set by
systemd accordingly to man:systemd.service(5) ... the only problem
with this schem is that /bin/bash nor any other shell does reset
its signal mask. I guess that systemd will support the init=/bin/bash
on the kernel command line. IMHO this requires a clean signal mask.
Werner
> > ---
> > src/core/main.c | 9 +++++++++
> > 1 file changed, 9 insertions(+)
> >
> > diff --git src/core/main.c src/core/main.c
> > index d5d1ee2..c082354 100644
> > --- src/core/main.c
> > +++ src/core/main.c
> > @@ -1831,6 +1831,7 @@ finish:
> > if (reexecute) {
> > const char **args;
> > unsigned i, args_size;
> > + sigset_t ss, o_ss;
> >
> > /* Close and disarm the watchdog, so that the new
> > * instance can reinitialize it, but doesn't get
> > @@ -1914,6 +1915,11 @@ finish:
> > args[i++] = NULL;
> > assert(i <= args_size);
> >
> > + /* reenable any blocked signals, especially important
> > + * if we switch from initial ramdisk to init=... */
> > + sigemptyset(&ss);
> > + sigprocmask(SIG_SETMASK,&ss,&o_ss);
> > +
> > if (switch_root_init) {
> > args[0] = switch_root_init;
> > execv(args[0], (char* const*) args);
> > @@ -1932,6 +1938,9 @@ finish:
> > log_error("Failed to execute /bin/sh, giving up:
> > %m");
> > } else
> > log_warning("Failed to execute /sbin/init, giving
> > up: %m");
> > +
> > + /* back to saved state if reexec failed */
> > + sigprocmask(SIG_SETMASK,&o_ss,NULL);
> > }
> >
> > if (arg_serialization) {
> > --
> > 1.7.9.2
Werner
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