Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal

Pull third pile of kernel_execve() patches from Al Viro:
 "The last bits of infrastructure for kernel_thread() et.al., with
  alpha/arm/x86 use of those.  Plus sanitizing the asm glue and
  do_notify_resume() on alpha, fixing the "disabled irq while running
  task_work stuff" breakage there.

  At that point the rest of kernel_thread/kernel_execve/sys_execve work
  can be done independently for different architectures.  The only
  pending bits that do depend on having all architectures converted are
  restrictred to fs/* and kernel/* - that'll obviously have to wait for
  the next cycle.

  I thought we'd have to wait for all of them done before we start
  eliminating the longjump-style insanity in kernel_execve(), but it
  turned out there's a very simple way to do that without flagday-style
  changes."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal:
  alpha: switch to saner kernel_execve() semantics
  arm: switch to saner kernel_execve() semantics
  x86, um: convert to saner kernel_execve() semantics
  infrastructure for saner ret_from_kernel_thread semantics
  make sure that kernel_thread() callbacks call do_exit() themselves
  make sure that we always have a return path from kernel_execve()
  ppc: eeh_event should just use kthread_run()
  don't bother with kernel_thread/kernel_execve for launching linuxrc
  alpha: get rid of switch_stack argument of do_work_pending()
  alpha: don't bother passing switch_stack separately from regs
  alpha: take SIGPENDING/NOTIFY_RESUME loop into signal.c
  alpha: simplify TIF_NEED_RESCHED handling

5 files changed, 3 insertions, 28 deletions

diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h
index 1e82e954e978..c03cd5a02364 100644
--- a/arch/um/include/asm/processor-generic.h
+++ b/arch/um/include/asm/processor-generic.h
@@ -26,7 +26,6 @@ struct thread_struct {
         jmp_buf *fault_catcher;
         struct task_struct *prev_sched;
         unsigned long temp_stack;
-        jmp_buf *exec_buf;
         struct arch_thread arch;
         jmp_buf switch_buf;
         int mm_count;
@@ -54,7 +53,6 @@ struct thread_struct {
         .fault_addr             = NULL, \
         .prev_sched             = NULL, \
         .temp_stack             = 0, \
-        .exec_buf               = NULL, \
         .arch                   = INIT_ARCH_THREAD, \
         .request                = { 0 } \
 }
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 44883049c11d..95feaa47a2fb 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -191,7 +191,6 @@ extern int os_getpid(void);
 extern int os_getpgrp(void);
 
 extern void init_new_thread_signals(void);
-extern int run_kernel_thread(int (*fn)(void *), void *arg, jmp_buf **jmp_ptr);
 
 extern int os_map_memory(void *virt, int fd, unsigned long long off,
                          unsigned long len, int r, int w, int x);
diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c
index ab019c7f0b57..3a8ece7d09ca 100644
--- a/arch/um/kernel/exec.c
+++ b/arch/um/kernel/exec.c
@@ -47,8 +47,3 @@ void start_thread(struct pt_regs *regs, unsigned long eip, unsigned long esp)
 #endif
 }
 EXPORT_SYMBOL(start_thread);
-
-void __noreturn ret_from_kernel_execve(struct pt_regs *unused)
-{
-        UML_LONGJMP(current->thread.exec_buf, 1);
-}
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 30629783b3e0..b6d699cdd557 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -135,14 +135,10 @@ void new_thread_handler(void)
         arg = current->thread.request.u.thread.arg;
 
         /*
-         * The return value is 1 if the kernel thread execs a process,
-         * 0 if it just exits
+         * callback returns only if the kernel thread execs a process
          */
-        n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
-        if (n == 1)
-                userspace(&current->thread.regs.regs);
-        else
-                do_exit(0);
+        n = fn(arg);
+        userspace(&current->thread.regs.regs);
 }
 
 /* Called magically, see new_thread_handler above */
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index 162bea3d91b2..b8f34c9e53ae 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -244,16 +244,3 @@ void init_new_thread_signals(void)
         signal(SIGWINCH, SIG_IGN);
         signal(SIGTERM, SIG_DFL);
 }
-
-int run_kernel_thread(int (*fn)(void *), void *arg, jmp_buf **jmp_ptr)
-{
-        jmp_buf buf;
-        int n;
-
-        *jmp_ptr = &buf;
-        n = UML_SETJMP(&buf);
-        if (n != 0)
-                return n;
-        (*fn)(arg);
-        return 0;
-}