[PATCH v2 02/10] netfilter: Avoid assigning 'const' pointer to non-const pointer

Will Deacon
2020-01-23T15:33:33Z

nf_remove_net_hook() uses WRITE_ONCE() to assign a 'const pointer to a
'non-const' pointer. Cleanups to the implementation of WRITE_ONCE() mean
that this will give rise to a compiler warning, just like a plain old
assignment would do:

| In file included from ./include/linux/export.h:43,
| from ./include/linux/linkage.h:7,
| from ./include/linux/kernel.h:8,
| from net/netfilter/core.c:9:
| net/netfilter/core.c: In function ‘nf_remove_net_hook’:
| ./include/linux/compiler.h:216:30: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
| *(volatile typeof(x) *)&(x) = (val); \
| ^
| net/netfilter/core.c:379:3: note: in expansion of macro ‘WRITE_ONCE’
| WRITE_ONCE(orig_ops[i], &dummy_ops);
| ^~~~~~~~~~

Follow the pattern used elsewhere in this file and add a cast to 'void *'
to squash the warning.

Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Jozsef Kadlecsik <kadlec@netfilter.org>
Cc: Florian Westphal <fw@strlen.de>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Will Deacon <will@kernel.org>
---
net/netfilter/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 78f046ec506f..3ac7c8c1548d 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -376,7 +376,7 @@ static bool nf_remove_net_hook(struct nf_hook_entries *old,
if (orig_ops[i] != unreg)
continue;
WRITE_ONCE(old->hooks[i].hook, accept_all);
- WRITE_ONCE(orig_ops[i], &dummy_ops);
+ WRITE_ONCE(orig_ops[i], (void *)&dummy_ops);
return true;
}

--
2.25.0.341.g760bfbb309-goog