[PATCH] Don't call FatalError from the signal handler

Edgar Toernig froese at gmx.de
Wed Apr 30 13:37:31 PDT 2008

Peter Hutterer wrote:
> Can I please have a review of the attached patch? The problem is 
> described in bug 10212.
> Bernardo Innocenti reported:
> "Very often I can freeze the Xorg server (git head) by typing
> my username in the gdm editbox.

Hmm... an app shouldn't be able to generate a segv in the
server...  has anyone tried to find the bug?

> Looks like a segfault happened and xf86SigHandler is trying
> to kill the server from _inside_ the SEGV signal handler,
> thus deadlocking on the global malloc arena lock.
> [...] 
> The attached patch sets up a siglongjmp environment and - in case of a 
> fatal error during a signal - jumps back to the set up state before 
> bringing down the server.

This won't help at all - the lock is still held.  A longjmp doesn't
magically unlocks all locks and brings all data structures back into
a consistent state.  It's really only a jump and the rules which
functions are save to be called still apply.

Ciao, ET.

PS: Not that it matters but why is malloc using locks anyway?  Last
time I looked the X-server was single threaded...

More information about the xorg mailing list