From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Ben Hutchings <ben@decadent.org.uk>
Cc: Sasha Levin <sashal@kernel.org>,
Jari Ruusu <jariruusu@users.sourceforge.net>,
stable <stable@vger.kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [stable] x86/atomic functions missing memory clobber
Date: Tue, 7 Jan 2020 19:14:50 +0100 [thread overview]
Message-ID: <20200107181450.GA2014625@kroah.com> (raw)
In-Reply-To: <90b417dcc1db1dfa637d9369af237879dda97e96.camel@decadent.org.uk>
On Tue, Jan 07, 2020 at 05:48:55PM +0000, Ben Hutchings wrote:
> I noticed that backports of commit 69d927bba395 "x86/atomic: Fix
> smp_mb__{before,after}_atomic()" didn't touch atomic_or_long() (present
> in 3.16) or atomic_inc_short() (present in 4.9 and earlier).
>
> These functions were only implemented on x86 and not actually used in-
> tree. But it's possible they are used by some out-of-tree module, and
> that commit removed compiler barriers for them.
>
> Would it might make sense to either
> 1. Add the memory clobber to these functions, or
> 2. Delete them
> on the affected stable branches?
Looks like we can drop atomic_inc_short for 4.9 as there are no users,
same for 4.4. I'll go do that now. It's not like the "fix" is really
needed here because of that :)
Good catch!
thanks,
greg k-h
next prev parent reply other threads:[~2020-01-07 18:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-07 17:48 [stable] x86/atomic functions missing memory clobber Ben Hutchings
2020-01-07 18:14 ` Greg Kroah-Hartman [this message]
2020-01-07 18:59 ` Ben Hutchings
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