[PATCH] FRV: Make futex code compilable on nommu [try #2]

Make the futex code compilable and usable on NOMMU by making the attempt to
handle page faults conditional on CONFIG_MMU.  If this is not enabled, then
we can assume that EFAULT returned from futex_atomic_op_inuser() is not
recoverable, and that the address lies outside of valid memory.

handle_mm_fault() is made to BUG if called on NOMMU without attempting to
invoke the actual handler (__handle_mm_fault).

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/kernel/futex.c b/kernel/futex.c
index 5e71a6bf6f6b..5efa2f978032 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -356,6 +356,13 @@ retry:
                 if (bh1 != bh2)
                         spin_unlock(&bh2->lock);
 
+#ifndef CONFIG_MMU
+                /* we don't get EFAULT from MMU faults if we don't have an MMU,
+                 * but we might get them from range checking */
+                ret = op_ret;
+                goto out;
+#endif
+
                 if (unlikely(op_ret != -EFAULT)) {
                         ret = op_ret;
                         goto out;