Re: [PATCH v2] net/sock: Update sk rcu iterator macro.

[Tim Hansen]

Mon, Oct 23, 2017 at 06:42:50PM +, Levin, Alexander (Sasha Levin) wrote:
> On Mon, Oct 23, 2017 at 11:39:22AM -0400, Tim Hansen wrote:
> >Mark hlist nodes in sk rcu iterator as protected by the rcu.
> >hlist_next_rcu accomplishes this and silences the warnings
> >sparse throws for net/ipv4/udp.c and net/ipv6/udp.c.
> >
> >Found with make C=1 net/ipv4/udp.o on linux-next tag
> >next-20171009.
> >
> >Signed-off-by: Tim Hansen 
> >---
> > include/net/sock.h | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> >diff --git a/include/net/sock.h b/include/net/sock.h
> >index 64e5ac41b9cf..96cb7b7e4924 100644
> >--- a/include/net/sock.h
> >+++ b/include/net/sock.h
> >@@ -737,10 +737,10 @@ static inline void sk_add_bind_node(struct sock *sk,
> >  *
> >  */
> > #define sk_for_each_entry_offset_rcu(tpos, pos, head, offset)   
> >\
> >-for (pos = rcu_dereference((head)->first); \
> >+for (pos = rcu_dereference(hlist_next_rcu((head)->first)); \
> 
> See below.
> 
> >  pos != NULL &&\
> > ({ tpos = (typeof(*tpos) *)((void *)pos - offset); 1;});   \
> >- pos = rcu_dereference(pos->next))
> >+ pos = rcu_dereference(hlist_next_rcu(pos->next)))
> 
> This will return the next-next node instead of just the next one. You
> probably want just hlist_next_rcu(pos) here.
> 
> -- 
> 
> Thanks,
> Sasha

Thanks Sasha, dumb oversight on my part. Sent in v3 of this patch.

Re: [PATCH v2] net/sock: Update sk rcu iterator macro.

[Levin, Alexander (Sasha Levin)]

On Mon, Oct 23, 2017 at 11:39:22AM -0400, Tim Hansen wrote:
>Mark hlist nodes in sk rcu iterator as protected by the rcu.
>hlist_next_rcu accomplishes this and silences the warnings
>sparse throws for net/ipv4/udp.c and net/ipv6/udp.c.
>
>Found with make C=1 net/ipv4/udp.o on linux-next tag
>next-20171009.
>
>Signed-off-by: Tim Hansen 
>---
> include/net/sock.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/include/net/sock.h b/include/net/sock.h
>index 64e5ac41b9cf..96cb7b7e4924 100644
>--- a/include/net/sock.h
>+++ b/include/net/sock.h
>@@ -737,10 +737,10 @@ static inline void sk_add_bind_node(struct sock *sk,
>  *
>  */
> #define sk_for_each_entry_offset_rcu(tpos, pos, head, offset)\
>-  for (pos = rcu_dereference((head)->first); \
>+  for (pos = rcu_dereference(hlist_next_rcu((head)->first)); \

See below.

>pos != NULL &&\
>   ({ tpos = (typeof(*tpos) *)((void *)pos - offset); 1;});   \
>-   pos = rcu_dereference(pos->next))
>+   pos = rcu_dereference(hlist_next_rcu(pos->next)))

This will return the next-next node instead of just the next one. You
probably want just hlist_next_rcu(pos) here.

-- 

Thanks,
Sasha

[PATCH v2] net/sock: Update sk rcu iterator macro.

[Tim Hansen]

Mark hlist nodes in sk rcu iterator as protected by the rcu.
hlist_next_rcu accomplishes this and silences the warnings
sparse throws for net/ipv4/udp.c and net/ipv6/udp.c.

Found with make C=1 net/ipv4/udp.o on linux-next tag 
next-20171009.

Signed-off-by: Tim Hansen 
---
 include/net/sock.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index 64e5ac41b9cf..96cb7b7e4924 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -737,10 +737,10 @@ static inline void sk_add_bind_node(struct sock *sk,
  *
  */
 #define sk_for_each_entry_offset_rcu(tpos, pos, head, offset) \
-   for (pos = rcu_dereference((head)->first); \
+   for (pos = rcu_dereference(hlist_next_rcu((head)->first)); \
 pos != NULL &&\
({ tpos = (typeof(*tpos) *)((void *)pos - offset); 1;});   \
-pos = rcu_dereference(pos->next))
+pos = rcu_dereference(hlist_next_rcu(pos->next)))
 
 static inline struct user_namespace *sk_user_ns(struct sock *sk)
 {
-- 
2.15.0.rc0