[PATCH] uidgid: Make uid_valid and gid_valid work with !CONFIG_MULTIUSER

[Josh Triplett]

{u,g}id_valid call {u,g}id_eq, which calls __k{u,g}id_val on both
arguments and compares.  With !CONFIG_MULTIUSER, __k{u,g}id_val return a
constant 0, which makes {u,g}id_valid always return false.  Change
{u,g}id_valid to compare their argument against -1 instead.  That
produces identical results in the normal CONFIG_MULTIUSER=y case, but
with !CONFIG_MULTIUSER will make {u,g}id_valid constant-fold into
"return true;" rather than "return false;".

This fixes uses of devpts without CONFIG_MULTIUSER.

Signed-off-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
---
 include/linux/uidgid.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/uidgid.h b/include/linux/uidgid.h
index 0ee05da..0383552 100644
--- a/include/linux/uidgid.h
+++ b/include/linux/uidgid.h
@@ -109,12 +109,12 @@ static inline bool gid_lte(kgid_t left, kgid_t right)
 
 static inline bool uid_valid(kuid_t uid)
 {
-	return !uid_eq(uid, INVALID_UID);
+	return __kuid_val(uid) != (uid_t) -1;
 }
 
 static inline bool gid_valid(kgid_t gid)
 {
-	return !gid_eq(gid, INVALID_GID);
+	return __kgid_val(gid) != (gid_t) -1;
 }
 
 #ifdef CONFIG_USER_NS
-- 
2.1.4

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