On Sat, 2014-10-04 at 11:57 +0200, Fabian Frederick wrote:
> -Add __rcu annotation on table to fix sparse warnings:
> net/phonet/pn_dev.c:279:25: warning: incorrect type in assignment (different
> address spaces)
> net/phonet/pn_dev.c:279:25: expected struct net_device *<noident>
> net/phonet/pn_dev.c:279:25: got void [noderef] <asn:4>*<noident>
> net/phonet/pn_dev.c:376:17: warning: incorrect type in assignment (different
> address spaces)
> net/phonet/pn_dev.c:376:17: expected struct net_device *volatile <noident>
> net/phonet/pn_dev.c:376:17: got struct net_device [noderef]
> <asn:4>*<noident>
> net/phonet/pn_dev.c:392:17: warning: incorrect type in assignment (different
> address spaces)
> net/phonet/pn_dev.c:392:17: expected struct net_device *<noident>
> net/phonet/pn_dev.c:392:17: got void [noderef] <asn:4>*<noident>
>
> -Access table with rcu_dereference (fixes the following sparse errors):
> net/phonet/pn_dev.c:278:25: error: incompatible types in comparison
> expression (different address spaces)
> net/phonet/pn_dev.c:391:17: error: incompatible types in comparison
> expression (different address spaces)
>
> Signed-off-by: Fabian Frederick <f...@skynet.be>
> ---
> net/phonet/pn_dev.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c
> index 56a6146..5c9c0b2f1 100644
> --- a/net/phonet/pn_dev.c
> +++ b/net/phonet/pn_dev.c
> @@ -36,7 +36,7 @@
>
> struct phonet_routes {
> struct mutex lock;
> - struct net_device *table[64];
> + struct net_device __rcu *table[64];
> };
>
> struct phonet_net {
> @@ -275,7 +275,7 @@ static void phonet_route_autodel(struct net_device *dev)
> bitmap_zero(deleted, 64);
> mutex_lock(&pnn->routes.lock);
> for (i = 0; i < 64; i++)
> - if (dev == pnn->routes.table[i]) {
> + if (rcu_dereference(pnn->routes.table[i]) == dev) {
> RCU_INIT_POINTER(pnn->routes.table[i], NULL);
> set_bit(i, deleted);
> }
> @@ -388,7 +388,7 @@ int phonet_route_del(struct net_device *dev, u8 daddr)
>
> daddr = daddr >> 2;
> mutex_lock(&routes->lock);
> - if (dev == routes->table[daddr])
> + if (rcu_dereference(routes->table[daddr]) == dev)
> RCU_INIT_POINTER(routes->table[daddr], NULL);
> else
> dev = NULL;
Hi Fabian
Have you tested this running the kernel with following config options :
CONFIG_LOCKDEP=y
CONFIG_PROVE_RCU=y
LOCKDEP should complain loudly, if not, we should file a bug !
Hint : Use rcu_access_pointer(), and check that LOCKDEP is happy with
that.
Thanks !
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