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Donenfeld" To: Uros Bizjak Cc: linux-kernel@vger.kernel.org, Theodore Ts'o Subject: Re: [PATCH] random: Use try_cmpxchg in _credit_init_bits Message-ID: References: <20220714182822.25142-1-ubizjak@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220714182822.25142-1-ubizjak@gmail.com> X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Uros, On Thu, Jul 14, 2022 at 08:28:22PM +0200, Uros Bizjak wrote: > Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old in > _credit_init_bits. x86 CMPXCHG instruction returns success in ZF flag, > so this change saves a compare after cmpxchg (and related move > instruction in front of cmpxchg). > > Also, try_cmpxchg implicitly assigns old *ptr value to "old" > when cmpxchg fails, enabling further code simplifications. > > No functional change intended. Applied as: https://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git/commit/?id=6a66e096619e3a737297eb2f9f535a287af43a95 Thanks for the patch. Jason