Re: Re: [PATCH] ipv6:ip6_xmit remove unnecessary np NULL check

On Thu, 2016-12-01 at 06:14 +0000, Rohit Thapliyal wrote:

Hi,

Hi,

Do not top post on netdev, and do not use HTML format : it wont reach
netdev.

 

Found at just one place in ping_v6_sendmsg, where np is checked for
NULL.

And I am not sure, if it is really required there also. 

So, I am not sure if sk_fullsock will ever return NULL in inet6_sk.

Well I am sure. You can trust me. You can read git history for the
details.

sk_fullsock(__sk) ? inet_sk(__sk)->pinet6 : NULL;

Yes, Lorenzo mentioned this ping_v6_sendmsg() useless code, but
apparently never sent the cleanup. This is really minor you know...

diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index 66e2d9dfc43a87ebed092d024e5bf2752b755d0e..775a9365725dd400c36e2510c685d08bf4a7d4b0 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c

@@ -125,12 +125,6 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		return PTR_ERR(dst);
 	rt = (struct rt6_info *) dst;
 
-	np = inet6_sk(sk);
-	if (!np) {
-		err = -EBADF;
-		goto dst_err_out;
-	}
-
 	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 		fl6.flowi6_oif = np->mcast_oif;
 	else if (!fl6.flowi6_oif)

@@ -165,7 +159,6 @@ static int ping_v6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 	}
 	release_sock(sk);
 
-dst_err_out:
 	dst_release(dst);
 
 	if (err)

Thanks, 

Rohit Thapliyal

 

--------- Original Message ---------

Sender : Eric Dumazet [off-list ref]

Date : 2016-11-30 00:26 (GMT+9)

Title : Re: [PATCH] ipv6:ip6_xmit remove unnecessary np NULL check

 

On Tue, 2016-11-29 at 12:02 +0530, Manjeet Pawar wrote:

quoted

From: Rohit Thapliyal <redacted>

np NULL check doesn't seem required here as it shall never
be NULL anyways in inet6_sk(sk).

Signed-off-by: Rohit Thapliyal <redacted>
Signed-off-by: Manjeet Pawar <redacted>
Signed-off-by: David Miller <davem@davemloft.net>
Reviewed-by: Akhilesh Kumar <redacted>

---
v2->v3: Modified as per the suggestion from David Miller
        ip6_xmit calls are made without checking NULL np
        pointer, so no need to explicitly check NULL np in
        ip6_xmit.

 include/linux/ipv6.h  | 2 +-
 net/ipv6/ip6_output.c | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index a064997..6c9c604 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h

@@ -299,7 +299,7 @@ struct tcp6_timewait_sock {
 
 static inline struct ipv6_pinfo *inet6_sk(const struct sock *__sk)
 {
-	return sk_fullsock(__sk) ? inet_sk(__sk)->pinet6 : NULL;
+	return inet_sk(__sk)->pinet6;

David suggestion was about np being NULL or not in ip6_xmit()

But have you checked inet6_sk() was never called for a TCPv6 TIMEWAIT or
SYN_RECV request ?

quoted

 }
 
 static inline struct raw6_sock *raw6_sk(const struct sock *sk)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 59eb4ed..f8c63ec 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c

@@ -213,8 +213,7 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
 	/*
 	 *	Fill in the IPv6 header
 	 */
-	if (np)
-		hlimit = np->hop_limit;
+	hlimit = np->hop_limit;
 	if (hlimit < 0)
 		hlimit = ip6_dst_hoplimit(dst);
 

This part is fine.




--

Thanks and Regards,

Rohit Thapliyal

Lead Engineer

Samsung SRI-D
Phone: +91-9717627969