On Thu, Apr 30, 2020 at 09:14:37AM +0200, Christian Brauner wrote: > On Thu, Apr 30, 2020 at 08:53:56AM +0200, Jiri Slaby wrote: > > On 30. 04. 20, 8:42, Arseny Maslennikov wrote: > > > This matches the behaviour of other Unix-like systems that have SIGINFO > > > and causes less harm to processes that do not install handlers for this > > > signal, making the keyboard status character non-fatal for them. > > > > > > This is implemented with the assumption that SIGINFO is defined > > > to be equivalent to SIGPWR; still, there is no reason for PWR to > > > result in termination of the signal recipient anyway — it does not > > > indicate there is a fatal problem with the recipient's execution > > > context (like e.g. FPE/ILL do), and we have TERM/KILL for explicit > > > termination requests. > > > > > > To put it another way: > > > The only scenario where system behaviour actually changes is when the > > > signal recipient has default disposition for SIGPWR. If a process > > > chose to interpret a SIGPWR as an incentive to cleanly terminate, it > > > would supply its own handler — and this commit does not affect processes > > > with non-default handlers. > > > > > > Signed-off-by: Arseny Maslennikov <ar@xxxxxxxxx> > > > --- > > > include/linux/signal.h | 5 +++-- > > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > > > diff --git a/include/linux/signal.h b/include/linux/signal.h > > > index 05bacd2ab..dc31da8fc 100644 > > > --- a/include/linux/signal.h > > > +++ b/include/linux/signal.h > > > @@ -369,7 +369,7 @@ extern bool unhandled_signal(struct task_struct *tsk, int sig); > > > * | SIGSYS/SIGUNUSED | coredump | > > > * | SIGSTKFLT | terminate | > > > * | SIGWINCH | ignore | > > > - * | SIGPWR | terminate | > > > + * | SIGPWR | ignore | > > > > You need to update signal.7 too: > > https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/man7/signal.7#n285 > > (I fail this whole thread via b4 and it appears that a bunch of messages > are missing on lore. Might just be delay though.) > > How this is this not going to break userspace? That's my main hesitation for taking this patchset. > Just for a start, SIGPWR (for better or worse) was used for a long time > by some sandboxing/container runtimes to shutdown a process and still > is. That's a good reason to not do this :( greg k-h
