xfrm: policy: Restore dir assignments in xfrm_hash_rebuild()

Clang warns (or errors with CONFIG_WERROR):

  net/xfrm/xfrm_policy.c:1286:8: error: variable 'dir' is uninitialized when used here [-Werror,-Wuninitialized]
   1286 |                 if ((dir & XFRM_POLICY_MASK) == XFRM_POLICY_OUT) {
        |                      ^~~
  net/xfrm/xfrm_policy.c:1257:9: note: initialize the variable 'dir' to silence this warning
   1257 |         int dir;
        |                ^
        |                 = 0
  1 error generated.

A recent refactoring removed some assignments to dir because
xfrm_policy_is_dead_or_sk() has a dir assignment in it. However, dir is
used elsewhere in xfrm_hash_rebuild(), including within loops where it
needs to be reloaded for each policy. Restore the assignments before the
first use of dir to fix the warning and ensure dir is properly
initialized throughout the function.

Fixes: 08c2182 ("xfrm: policy: use recently added helper in more places")
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

Author: nathanchance

net/xfrm/xfrm_policy.c

@@ -1283,6 +1283,7 @@ static void xfrm_hash_rebuild(struct work_struct *work)
 		if (xfrm_policy_is_dead_or_sk(policy))
 			continue;
 
+		dir = xfrm_policy_id2dir(policy->index);
 		if ((dir & XFRM_POLICY_MASK) == XFRM_POLICY_OUT) {
 			if (policy->family == AF_INET) {
 				dbits = rbits4;
@@ -1337,6 +1338,7 @@ static void xfrm_hash_rebuild(struct work_struct *work)
 		hlist_del_rcu(&policy->bydst);
 
 		newpos = NULL;
+		dir = xfrm_policy_id2dir(policy->index);
 		chain = policy_hash_bysel(net, &policy->selector,
 					  policy->family, dir);