[S390] ptrace inferior call interactions with TIF_SYSCALL

The TIF_SYSCALL bit needs to be cleared if the debugger changes the state
of the ptraced process in regard to the presence of a system call.
Otherwise the system call will be restarted although the debugger set up
an inferior call.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: stable@kernel.org

diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 05a85bc14c98a2556e86bf40cec7e76de2dc2423..7f6f9f35454518f091e4fb86e3d39e46c8aaf391 100644 (file)
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -460,9 +460,9 @@ void do_signal(struct pt_regs *regs)
                                                     regs->svc_code >> 16);
                                break;
                        }
-                       /* No longer in a system call */
-                       clear_thread_flag(TIF_SYSCALL);
                }
+               /* No longer in a system call */
+               clear_thread_flag(TIF_SYSCALL);
 
                if ((is_compat_task() ?
                     handle_signal32(signr, &ka, &info, oldset, regs) :
@@ -486,6 +486,7 @@ void do_signal(struct pt_regs *regs)
        }
 
        /* No handlers present - check for system call restart */
+       clear_thread_flag(TIF_SYSCALL);
        if (current_thread_info()->system_call) {
                regs->svc_code = current_thread_info()->system_call;
                switch (regs->gprs[2]) {
@@ -500,9 +501,6 @@ void do_signal(struct pt_regs *regs)
                        regs->gprs[2] = regs->orig_gpr2;
                        set_thread_flag(TIF_SYSCALL);
                        break;
-               default:
-                       clear_thread_flag(TIF_SYSCALL);
-                       break;
                }
        }