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Date:   Tue, 14 May 2019 12:25:09 -0700
From:   Jakub Kicinski <jakub.kicinski@netronome.com>
To:     NeilBrown <neilb@suse.com>
Cc:     Thomas Graf <tgraf@suug.ch>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        David Miller <davem@davemloft.net>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH 2/5] rhashtable: reorder some inline functions and
 macros.
Message-ID: <20190514122509.46ab191a@cakuba.netronome.com>
In-Reply-To: <155503392797.17793.15780367123758287135.stgit@noble.brown>
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        <155503392797.17793.15780367123758287135.stgit@noble.brown>
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On Fri, 12 Apr 2019 11:52:08 +1000, NeilBrown wrote:
> This patch only moves some code around, it doesn't
> change the code at all.
> A subsequent patch will benefit from this as it needs
> to add calls to functions which are now defined before the
> call-site, but weren't before.
> 
> Signed-off-by: NeilBrown <neilb@suse.com>

Hi Neil, I think this patch introduces as slew of sparse warnigns:

include/linux/rhashtable.h:724:23: warning: incorrect type in argument 2 (different address spaces)
include/linux/rhashtable.h:724:23:    expected struct rhash_lock_head **bkt
include/linux/rhashtable.h:724:23:    got struct rhash_lock_head [noderef] <asn:4>**[assigned] bkt
include/linux/rhashtable.h:728:33: warning: incorrect type in argument 2 (different address spaces)
include/linux/rhashtable.h:728:33:    expected struct rhash_lock_head **bkt
include/linux/rhashtable.h:728:33:    got struct rhash_lock_head [noderef] <asn:4>**[assigned] bkt
include/linux/rhashtable.h:760:41: warning: incorrect type in argument 2 (different address spaces)
include/linux/rhashtable.h:760:41:    expected struct rhash_lock_head **bkt
include/linux/rhashtable.h:760:41:    got struct rhash_lock_head [noderef] <asn:4>**[assigned] bkt
include/linux/rhashtable.h:801:25: warning: incorrect type in argument 2 (different address spaces)
include/linux/rhashtable.h:801:25:    expected struct rhash_lock_head **bkt
include/linux/rhashtable.h:801:25:    got struct rhash_lock_head [noderef] <asn:4>**[assigned] bkt
include/linux/rhashtable.h:1003:23: warning: incorrect type in argument 2 (different address spaces)
include/linux/rhashtable.h:1003:23:    expected struct rhash_lock_head **bkt
include/linux/rhashtable.h:1003:23:    got struct rhash_lock_head [noderef] <asn:4>**[assigned] bkt
include/linux/rhashtable.h:1047:41: warning: incorrect type in argument 2 (different address spaces)
include/linux/rhashtable.h:1047:41:    expected struct rhash_lock_head **bkt
include/linux/rhashtable.h:1047:41:    got struct rhash_lock_head [noderef] <asn:4>**[assigned] bkt
include/linux/rhashtable.h:1054:25: warning: incorrect type in argument 2 (different address spaces)
include/linux/rhashtable.h:1054:25:    expected struct rhash_lock_head **bkt
include/linux/rhashtable.h:1054:25:    got struct rhash_lock_head [noderef] <asn:4>**[assigned] bkt

Is there any chance to get those fixed?  Presumably a __force would be
appropriate?  Maybe like this?

diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index f7714d3b46bd..997017a85032 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -325,27 +325,28 @@ static inline struct rhash_lock_head __rcu **rht_bucket_insert(
  */
 
 static inline void rht_lock(struct bucket_table *tbl,
-                           struct rhash_lock_head **bkt)
+                           struct rhash_lock_head __rcu **bkt)
 {
+
        local_bh_disable();
-       bit_spin_lock(0, (unsigned long *)bkt);
+       bit_spin_lock(0, (unsigned long __force *)bkt);
        lock_map_acquire(&tbl->dep_map);
 }
 
 static inline void rht_lock_nested(struct bucket_table *tbl,
-                                  struct rhash_lock_head **bucket,
+                                  struct rhash_lock_head __rcu **bkt,
                                   unsigned int subclass)
 {
        local_bh_disable();
-       bit_spin_lock(0, (unsigned long *)bucket);
+       bit_spin_lock(0, (unsigned long __force *)bkt);
        lock_acquire_exclusive(&tbl->dep_map, subclass, 0, NULL, _THIS_IP_);
 }
 
 static inline void rht_unlock(struct bucket_table *tbl,
-                             struct rhash_lock_head **bkt)
+                             struct rhash_lock_head __rcu **bkt)
 {
        lock_map_release(&tbl->dep_map);
-       bit_spin_unlock(0, (unsigned long *)bkt);
+       bit_spin_unlock(0, (unsigned long __force *)bkt);
        local_bh_enable();
 }