linux-kernel - Re: [PATCH v2] fscrypt: avoid data race on fscrypt_mode::logged_impl

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Message-ID: <20191106210204.GA139580@gmail.com>
Date:   Wed, 6 Nov 2019 13:02:05 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     linux-fscrypt@...r.kernel.org
Cc:     "Theodore Y . Ts'o" <tytso@....edu>,
        Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] fscrypt: avoid data race on
 fscrypt_mode::logged_impl_name

On Mon, Oct 21, 2019 at 01:49:03PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@...gle.com>
> 
> The access to logged_impl_name is technically a data race, which tools
> like KCSAN could complain about in the future.  See:
> https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE
> 
> Fix by using xchg(), which also ensures that only one thread does the
> logging.
> 
> This also required switching from bool to int, to avoid a build error on
> the RISC-V architecture which doesn't implement xchg on bytes.
> 
> Signed-off-by: Eric Biggers <ebiggers@...gle.com>

Applied to fscrypt.git#master for 5.5.

- Eric