signal: make force_sigsegv() void

Patch series "signal: refactor some functions", v3.

This series refactors a bunch of functions in signal.c to simplify parts
of the code.

The greatest single change is declaring the static do_sigpending() helper
as void which makes it possible to remove a bunch of unnecessary checks in
the syscalls later on.

This patch (of 17):

force_sigsegv() returned 0 unconditionally so it doesn't make sense to have
it return at all. In addition, there are no callers that check
force_sigsegv()'s return value.

Link: http://lkml.kernel.org/r/20180602103653.18181-2-christian@brauner.io
Signed-off-by: Christian Brauner <christian@brauner.io>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: James Morris <james.morris@microsoft.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/sched/signal.h

@@ -314,7 +314,7 @@ int force_sig_pkuerr(void __user *addr, u32 pkey);
 int force_sig_ptrace_errno_trap(int errno, void __user *addr);
 
 extern int send_sig_info(int, struct siginfo *, struct task_struct *);
-extern int force_sigsegv(int, struct task_struct *);
+extern void force_sigsegv(int sig, struct task_struct *p);
 extern int force_sig_info(int, struct siginfo *, struct task_struct *);
 extern int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp);
 extern int kill_pid_info(int sig, struct siginfo *info, struct pid *pid);

kernel/signal.c

@@ -1458,8 +1458,7 @@ send_sig(int sig, struct task_struct *p, int priv)
 	return send_sig_info(sig, __si_special(priv), p);
 }
 
-void
-force_sig(int sig, struct task_struct *p)
+void force_sig(int sig, struct task_struct *p)
 {
 	force_sig_info(sig, SEND_SIG_PRIV, p);
 }
@@ -1470,8 +1469,7 @@ force_sig(int sig, struct task_struct *p)
  * the problem was already a SIGSEGV, we'll want to
  * make sure we don't even try to deliver the signal..
  */
-int
-force_sigsegv(int sig, struct task_struct *p)
+void force_sigsegv(int sig, struct task_struct *p)
 {
 	if (sig == SIGSEGV) {
 		unsigned long flags;
@@ -1480,7 +1478,6 @@ force_sigsegv(int sig, struct task_struct *p)
 		spin_unlock_irqrestore(&p->sighand->siglock, flags);
 	}
 	force_sig(SIGSEGV, p);
-	return 0;
 }
 
 int force_sig_fault(int sig, int code, void __user *addr