Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1233294

Re: netlink: Add netlink_bound helper and use it in netlink_getname

Show all headers | View raw

Hello,

On Sun, Sep 27, 2015 at 04:10:41AM +0800, Herbert Xu wrote:
> Well guess what the bug that you have discovered supposedly due to
> a missing barrier in netlink_connect has nothing to do with the
> barrier.  Instead it is caused by a logical error elsewhere that
> would have gone unnoticed otherwise.

It's a combination of two problems.  The garbage port number is a
logical error but there still is an ordering problem there between
->bound and ->portid.  We need to test ->bind there again because of
the garbage port problem.

> So I retain my position that blindly adding barriers do not make
> bugs go away.  Instead you need to have real understanding of what

That's a dishonest summary of what I've been saying.

> the code is doing and every spot where a barrier may be needed must
> be audited manually.

What I've been saying is that we do need to be careful and audit each
barrier usages but at the same time there are established patterns
that we can use to make the process significantly easier and more
reliable.

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH v2] netlink: Replace rhash_portid with bound David Miller <davem@davemloft.net> - 2015-09-24 21:20 +0200
  Re: [PATCH v2] netlink: Replace rhash_portid with bound Tejun Heo <tj@kernel.org> - 2015-09-24 22:10 +0200
    netlink: Add barrier to netlink_connect for theoretical case Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-25 03:50 +0200
      Re: netlink: Add barrier to netlink_connect for theoretical case Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-25 05:30 +0200
        Re: netlink: Add barrier to netlink_connect for theoretical case Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-25 05:50 +0200
          Re: netlink: Add barrier to netlink_connect for theoretical case Tejun Heo <tj@kernel.org> - 2015-09-25 17:10 +0200
      Re: netlink: Add barrier to netlink_connect for theoretical case Tejun Heo <tj@kernel.org> - 2015-09-25 17:10 +0200
        netlink: Add netlink_bound helper and use it in netlink_getname Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-26 15:20 +0200
          Re: netlink: Add netlink_bound helper and use it in netlink_getname Tejun Heo <tj@kernel.org> - 2015-09-26 20:10 +0200
            Re: netlink: Add netlink_bound helper and use it in netlink_getname Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-26 21:50 +0200
              Re: netlink: Add netlink_bound helper and use it in netlink_getname Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-26 22:00 +0200
                Re: netlink: Add netlink_bound helper and use it in netlink_getname Tejun Heo <tj@kernel.org> - 2015-09-26 22:10 +0200
                Re: netlink: Add netlink_bound helper and use it in netlink_getname Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-26 22:20 +0200
                Re: netlink: Add netlink_bound helper and use it in netlink_getname Tejun Heo <tj@kernel.org> - 2015-09-26 22:20 +0200
              Re: netlink: Add netlink_bound helper and use it in netlink_getname Tejun Heo <tj@kernel.org> - 2015-09-26 22:00 +0200
            Re: netlink: Add netlink_bound helper and use it in netlink_getname Herbert Xu <herbert@gondor.apana.org.au> - 2015-09-26 21:50 +0200
              Re: netlink: Add netlink_bound helper and use it in netlink_getname Tejun Heo <tj@kernel.org> - 2015-09-26 21:50 +0200

csiph-web