On Wed, Feb 07, 2018 at 12:03:56PM +0000, Simon McVittie wrote: > On Wed, 07 Feb 2018 at 12:51:14 +0200, Pekka Paalanen wrote: > > Catching an ABRT is kind of ok, catching a SEGV is russian roulette. We > > have been quite lucky with it, but I've started hitting crashes inside > > malloc() which causes a deadlock when our SEGV handler needs to malloc() > > as well (weston_log_timestamp()). > > This isn't unique to SIGSEGV: inside any POSIX async-signal handler, > you can only (portably, safely) use functions that are documented to be > async-signal-safe, which basically means syscall wrappers. See > signal-safety(7) on a Linux system.
fun fact: printf() is not in that list of functions. so printf() from within a signal handler may or may not go boom. Cheers, Peter > > (If anything in the Wayland/Weston stack reloads configuration on SIGHUP, > it should probably use the standard "pipe-to-self trick", like e.g. > dbus-daemon does - write a byte to a pipe using async-signal-safe write(), > poll that pipe in the main loop, and reload configuration from the main > loop whenever one or more bytes can be read from the pipe. That's a > safe pattern.) > > > Therefore, this code does more harm than it is useful, so remove it. We > > also drop an optional dependency to libunwind. > > I am not a Wayland reviewer, but I think this is an excellent idea. The > best signal handlers are SIG_DFL and SIG_IGN :-) > > smcv > _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/wayland-devel
