On Thu 28 Feb 2019 at 00:49, Cong Wang <xiyou.wangc...@gmail.com> wrote: > On Tue, Feb 26, 2019 at 6:57 AM Vlad Buslov <vla...@mellanox.com> wrote: >> >> >> On Mon 25 Feb 2019 at 22:39, Cong Wang <xiyou.wangc...@gmail.com> wrote: >> > On Mon, Feb 25, 2019 at 8:11 AM Vlad Buslov <vla...@mellanox.com> wrote: >> >> >> >> >> >> On Fri 22 Feb 2019 at 19:32, Cong Wang <xiyou.wangc...@gmail.com> wrote: >> >> > >> >> > So if it is no longer RCU any more, why do you still use >> >> > rcu_dereference_protected()? That is, why not just deref it as a raw >> >> > pointer? >> > >> > >> > Any answer for this question? >> >> I decided that since there is neither possibility of concurrent pointer >> assignment nor deallocation of object that it points to, most performant >> solution would be using rcu_dereference_protected() which is the only >> RCU dereference helper that doesn't use READ_ONCE. I now understand that >> this is confusing (and most likely doesn't provide any noticeable >> performance improvement anyway!) and will change this patch to use >> rcu_dereference_raw() as you suggest. > > Yeah, please make sure sparse is happy with that. :)
I checked my flower change with sparse. It produced a lot of warnings, some of which are several years old. None in the code I changed though: CHECK net/sched/cls_flower.c net/sched/cls_flower.c:200:20: warning: cast from restricted __be16 net/sched/cls_flower.c:200:20: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:200:20: expected unsigned short [usertype] val net/sched/cls_flower.c:200:20: got restricted __be16 [usertype] dst net/sched/cls_flower.c:200:20: warning: cast from restricted __be16 net/sched/cls_flower.c:200:20: warning: cast from restricted __be16 net/sched/cls_flower.c:201:20: warning: cast from restricted __be16 net/sched/cls_flower.c:201:20: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:201:20: expected unsigned short [usertype] val net/sched/cls_flower.c:201:20: got restricted __be16 [usertype] dst net/sched/cls_flower.c:201:20: warning: cast from restricted __be16 net/sched/cls_flower.c:201:20: warning: cast from restricted __be16 net/sched/cls_flower.c:202:19: warning: cast from restricted __be16 net/sched/cls_flower.c:202:19: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:202:19: expected unsigned short [usertype] val net/sched/cls_flower.c:202:19: got restricted __be16 [usertype] dst net/sched/cls_flower.c:202:19: warning: cast from restricted __be16 net/sched/cls_flower.c:202:19: warning: cast from restricted __be16 net/sched/cls_flower.c:203:19: warning: cast from restricted __be16 net/sched/cls_flower.c:203:19: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:203:19: expected unsigned short [usertype] val net/sched/cls_flower.c:203:19: got restricted __be16 [usertype] dst net/sched/cls_flower.c:203:19: warning: cast from restricted __be16 net/sched/cls_flower.c:203:19: warning: cast from restricted __be16 net/sched/cls_flower.c:206:21: warning: cast from restricted __be16 net/sched/cls_flower.c:206:21: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:206:21: expected unsigned short [usertype] val net/sched/cls_flower.c:206:21: got restricted __be16 [usertype] dst net/sched/cls_flower.c:206:21: warning: cast from restricted __be16 net/sched/cls_flower.c:206:21: warning: cast from restricted __be16 net/sched/cls_flower.c:206:21: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:206:42: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:207:21: warning: cast from restricted __be16 net/sched/cls_flower.c:207:21: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:207:21: expected unsigned short [usertype] val net/sched/cls_flower.c:207:21: got restricted __be16 [usertype] dst net/sched/cls_flower.c:207:21: warning: cast from restricted __be16 net/sched/cls_flower.c:207:21: warning: cast from restricted __be16 net/sched/cls_flower.c:207:21: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:207:42: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:223:20: warning: cast from restricted __be16 net/sched/cls_flower.c:223:20: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:223:20: expected unsigned short [usertype] val net/sched/cls_flower.c:223:20: got restricted __be16 [usertype] src net/sched/cls_flower.c:223:20: warning: cast from restricted __be16 net/sched/cls_flower.c:223:20: warning: cast from restricted __be16 net/sched/cls_flower.c:224:20: warning: cast from restricted __be16 net/sched/cls_flower.c:224:20: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:224:20: expected unsigned short [usertype] val net/sched/cls_flower.c:224:20: got restricted __be16 [usertype] src net/sched/cls_flower.c:224:20: warning: cast from restricted __be16 net/sched/cls_flower.c:224:20: warning: cast from restricted __be16 net/sched/cls_flower.c:225:19: warning: cast from restricted __be16 net/sched/cls_flower.c:225:19: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:225:19: expected unsigned short [usertype] val net/sched/cls_flower.c:225:19: got restricted __be16 [usertype] src net/sched/cls_flower.c:225:19: warning: cast from restricted __be16 net/sched/cls_flower.c:225:19: warning: cast from restricted __be16 net/sched/cls_flower.c:226:19: warning: cast from restricted __be16 net/sched/cls_flower.c:226:19: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:226:19: expected unsigned short [usertype] val net/sched/cls_flower.c:226:19: got restricted __be16 [usertype] src net/sched/cls_flower.c:226:19: warning: cast from restricted __be16 net/sched/cls_flower.c:226:19: warning: cast from restricted __be16 net/sched/cls_flower.c:229:21: warning: cast from restricted __be16 net/sched/cls_flower.c:229:21: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:229:21: expected unsigned short [usertype] val net/sched/cls_flower.c:229:21: got restricted __be16 [usertype] src net/sched/cls_flower.c:229:21: warning: cast from restricted __be16 net/sched/cls_flower.c:229:21: warning: cast from restricted __be16 net/sched/cls_flower.c:229:21: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:229:42: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:230:21: warning: cast from restricted __be16 net/sched/cls_flower.c:230:21: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:230:21: expected unsigned short [usertype] val net/sched/cls_flower.c:230:21: got restricted __be16 [usertype] src net/sched/cls_flower.c:230:21: warning: cast from restricted __be16 net/sched/cls_flower.c:230:21: warning: cast from restricted __be16 net/sched/cls_flower.c:230:21: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:230:42: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:744:14: warning: cast from restricted __be16 net/sched/cls_flower.c:744:14: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:744:14: expected unsigned short [usertype] val net/sched/cls_flower.c:744:14: got restricted __be16 [usertype] dst net/sched/cls_flower.c:744:14: warning: cast from restricted __be16 net/sched/cls_flower.c:744:14: warning: cast from restricted __be16 net/sched/cls_flower.c:744:40: warning: cast from restricted __be16 net/sched/cls_flower.c:744:40: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:744:40: expected unsigned short [usertype] val net/sched/cls_flower.c:744:40: got restricted __be16 [usertype] dst net/sched/cls_flower.c:744:40: warning: cast from restricted __be16 net/sched/cls_flower.c:744:40: warning: cast from restricted __be16 net/sched/cls_flower.c:744:14: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:744:40: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:746:15: warning: cast from restricted __be16 net/sched/cls_flower.c:746:15: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:746:15: expected unsigned short [usertype] val net/sched/cls_flower.c:746:15: got restricted __be16 [usertype] src net/sched/cls_flower.c:746:15: warning: cast from restricted __be16 net/sched/cls_flower.c:746:15: warning: cast from restricted __be16 net/sched/cls_flower.c:746:41: warning: cast from restricted __be16 net/sched/cls_flower.c:746:41: warning: incorrect type in argument 1 (different base types) net/sched/cls_flower.c:746:41: expected unsigned short [usertype] val net/sched/cls_flower.c:746:41: got restricted __be16 [usertype] src net/sched/cls_flower.c:746:41: warning: cast from restricted __be16 net/sched/cls_flower.c:746:41: warning: cast from restricted __be16 net/sched/cls_flower.c:746:15: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:746:41: warning: restricted __be16 degrades to integer net/sched/cls_flower.c:830:15: warning: cast to restricted __be32 net/sched/cls_flower.c:830:15: warning: cast to restricted __be32 net/sched/cls_flower.c:830:15: warning: cast to restricted __be32 net/sched/cls_flower.c:830:15: warning: cast to restricted __be32 net/sched/cls_flower.c:830:15: warning: cast to restricted __be32 net/sched/cls_flower.c:830:15: warning: cast to restricted __be32 net/sched/cls_flower.c:831:16: warning: cast to restricted __be32 net/sched/cls_flower.c:831:16: warning: cast to restricted __be32 net/sched/cls_flower.c:831:16: warning: cast to restricted __be32 net/sched/cls_flower.c:831:16: warning: cast to restricted __be32 net/sched/cls_flower.c:831:16: warning: cast to restricted __be32 net/sched/cls_flower.c:831:16: warning: cast to restricted __be32 Cong, Jiri, do you want me to send patch that fixes all of these first? Regards, Vlad
