[PATCH] uml: fix strace -f

It turns out that we need to check for pending signals when a newly forked
process is run for the first time.  With strace -f, strace needs to know about
the forked process before it gets going.  If it doesn't, then it ptraces some
bogus values into its registers, and the process segfaults.  So, I added calls
to interrupt_end, which does that, plus checks for reschedules.  There
shouldn't be any of those, but x86 does the same thing, so I'm copying that
behavior to be safe.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/um/kernel/skas/process_kern.c b/arch/um/kernel/skas/process_kern.c
index ab5d327..fc71ef2 100644 (file)
--- a/arch/um/kernel/skas/process_kern.c
+++ b/arch/um/kernel/skas/process_kern.c
@@ -68,8 +68,11 @@ void new_thread_handler(int sig)
         * 0 if it just exits
         */
        n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
-       if(n == 1)
+       if(n == 1){
+               /* Handle any immediate reschedules or signals */
+               interrupt_end();
                userspace(&current->thread.regs.regs);
+       }
        else do_exit(0);
 }
 
@@ -96,6 +99,8 @@ void fork_handler(int sig)
        schedule_tail(current->thread.prev_sched);
        current->thread.prev_sched = NULL;
 
+       /* Handle any immediate reschedules or signals */
+       interrupt_end();
        userspace(&current->thread.regs.regs);
 }