[PATCH] uml: Fix SKAS sig-handler reentrancy

This adds code which enables SIGSEGV reception to the SKAS sig_handler_common,
which matches the tt code.

I still need to figure out why the SA_NODEFER flag was backed out in favor of
this.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
CC: uml-devel <user-mode-linux-devel@lists.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/kernel/skas/trap_user.c

@@ -20,6 +20,14 @@ void sig_handler_common_skas(int sig, void *sc_ptr)
 	int save_errno = errno;
 	int save_user;
 
+	/* This is done because to allow SIGSEGV to be delivered inside a SEGV
+	 * handler.  This can happen in copy_user, and if SEGV is disabled,
+	 * the process will die.
+	 * XXX Figure out why this is better than SA_NODEFER
+	 */
+	if(sig == SIGSEGV)
+		change_sig(SIGSEGV, 1);
+
 	r = &TASK_REGS(get_current())->skas;
 	save_user = r->is_user;
 	r->is_user = 0;