On Wed, 7 Feb 2018 12:03:56 +0000 Simon McVittie <s...@collabora.com> 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. > > (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.) Weston handles all other signals via signalfd(), these were the only ones that used the signal()/sigaction() kind of API. There is no way to reload config at runtime. :-P > > 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 :-) Heh, cool. Thanks, pq
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