From: Neil Brown <neilb@suse.de>
To: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
linux-next@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: linux-next: build warning after merge of the rcu tree
Date: Mon, 6 Sep 2010 12:32:55 +1000 [thread overview]
Message-ID: <20100906123255.3eef4311@notabene> (raw)
In-Reply-To: <20100906121408.33946fbe.sfr@canb.auug.org.au>
On Mon, 6 Sep 2010 12:14:08 +1000
Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> Hi Paul,
>
> After merging the rcu tree, today's linux-next build
> (powerpc ppc64_defconfig) produced this warning:
>
> drivers/md/raid1.c: In function 'read_balance':
> drivers/md/raid1.c:445: warning: operation on 'new_disk' may be undefined
>
> I am picking on the rcu tree because the line above has not changed since
> 2005. The line is:
>
> for (rdev = rcu_dereference(conf->mirrors[new_disk].rdev);
> r1_bio->bios[new_disk] == IO_BLOCKED ||
> !rdev || !test_bit(In_sync, &rdev->flags)
> || test_bit(WriteMostly, &rdev->flags);
> rdev = rcu_dereference(conf->mirrors[++new_disk].rdev)) {
>
> Where new_disk is being updated in the parameter to the last
> rcu_dereference.
>
Hi Stephen,
There is a patch in linux-kernel
"PATCH] md: do not use ++ in rcu_dereference() argument"
that addresses this - it is a problem in md: I guess rcu as become more
helpful in finding these problems.
I'll probably fix it a little differently, but I'll have something in my
for-next for tomorrow.
Thanks,
NeilBrown
next prev parent reply other threads:[~2010-09-06 2:32 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-06 2:14 linux-next: build warning after merge of the rcu tree Stephen Rothwell
2010-09-06 2:32 ` Neil Brown [this message]
2010-09-06 3:02 ` Stephen Rothwell
2010-09-06 5:37 ` Paul E. McKenney
2011-03-25 5:05 Stephen Rothwell
2011-03-25 19:23 ` Paul E. McKenney
2011-08-24 4:23 Stephen Rothwell
2011-08-24 12:27 ` Paul E. McKenney
2011-08-25 0:46 ` Arnaud Lacombe
2011-08-25 5:04 ` Paul E. McKenney
2017-06-21 6:48 Stephen Rothwell
2017-06-21 13:30 ` Paul E. McKenney
2019-12-12 5:06 Stephen Rothwell
2019-12-12 6:02 ` Paul E. McKenney
2019-12-12 6:38 ` Eric Dumazet
2019-12-12 6:57 ` Eric Dumazet
2020-01-10 21:57 ` Paul E. McKenney
2020-01-15 16:42 ` Paul E. McKenney
2019-12-12 11:40 ` Stephen Rothwell
2019-12-13 1:31 ` Paul E. McKenney
2020-01-06 17:51 ` Olof Johansson
2020-01-06 18:10 ` Paul E. McKenney
2020-01-06 21:08 ` Olof Johansson
2020-01-06 21:43 ` Paul E. McKenney
2020-03-10 2:27 Stephen Rothwell
2020-03-10 2:49 ` Paul E. McKenney
2020-12-07 8:20 Stephen Rothwell
2020-12-07 16:47 ` Paul E. McKenney
2020-12-07 17:48 ` Jonathan Corbet
2020-12-07 18:53 ` Paul E. McKenney
2021-03-04 1:41 Stephen Rothwell
2021-03-04 1:48 ` Paul E. McKenney
2022-06-15 5:38 Stephen Rothwell
2022-06-15 13:55 ` Paul E. McKenney
2022-11-07 3:26 Stephen Rothwell
2022-11-07 5:02 ` Paul E. McKenney
2023-03-21 2:50 Stephen Rothwell
2023-03-21 3:01 ` Boqun Feng
2023-04-06 4:43 Stephen Rothwell
2023-04-06 14:15 ` Paul E. McKenney
2023-07-26 2:32 Stephen Rothwell
2023-07-26 3:33 ` Paul E. McKenney
2023-07-26 3:48 ` Paul E. McKenney
2023-07-26 6:37 ` Stephen Rothwell
2024-01-25 3:33 Stephen Rothwell
2024-01-25 13:18 ` Paul E. McKenney
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