[Qemu-ppc] [PATCH for-1.6 1/2] linux-user/signal.c: PPC: Silence clang uninitialized-use warning

[Peter Maydell]

Silence a clang warning in a PPC signal return function:

/home/petmay01/linaro/qemu-from-laptop/qemu/linux-user/signal.c:4611:9: error: 
variable 'sr_addr' is used
      uninitialized whenever 'if' condition is true 
[-Werror,-Wsometimes-uninitialized]
    if (!lock_user_struct(VERIFY_READ, sc, sc_addr, 1))
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/petmay01/linaro/qemu-from-laptop/qemu/linux-user/signal.c:4636:28: note: 
uninitialized use occurs here
    unlock_user_struct(sr, sr_addr, 1);
                           ^~~~~~~
/home/petmay01/linaro/qemu-from-laptop/qemu/linux-user/qemu.h:442:27: note: 
expanded from macro 'unlock_user_struct'
    unlock_user(host_ptr, guest_addr, (copy) ? sizeof(*host_ptr) : 0)
                          ^

This happens when we unlock a user struct which we never
attempted to lock. Strictly, clang is actually wrong here -- it
hasn't been able to spot that unlock_user_struct() doesn't use
its second argument if the first is NULL. However it doesn't
seem too unreasonable to demand that we pass in initialized
values to it.

Signed-off-by: Peter Maydell <address@hidden>
---
 linux-user/signal.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/linux-user/signal.c b/linux-user/signal.c
index a5e8906..d63777d 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -4603,7 +4603,7 @@ long do_sigreturn(CPUPPCState *env)
 {
     struct target_sigcontext *sc = NULL;
     struct target_mcontext *sr = NULL;
-    target_ulong sr_addr, sc_addr;
+    target_ulong sr_addr = 0, sc_addr;
     sigset_t blocked;
     target_sigset_t set;
 
-- 
1.7.9.5