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[66.111.4.227]) by smtp.gmail.com with ESMTPSA id t26sm44632518qtc.95.2019.08.05.07.43.26 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Aug 2019 07:43:27 -0700 (PDT) Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailauth.nyi.internal (Postfix) with ESMTP id 0AAFA21ADD; Mon, 5 Aug 2019 10:43:26 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute6.internal (MEProxy); Mon, 05 Aug 2019 10:43:26 -0400 X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduvddruddtjedgjeekucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvffukfhfgggtuggjfgesghdtreertdervdenucfhrhhomhepuehoqhhu nhcuhfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtohhmqeenucfkphepge ehrdefvddruddvkedruddtleenucfrrghrrghmpehmrghilhhfrhhomhepsghoqhhunhdo mhgvshhmthhprghuthhhphgvrhhsohhnrghlihhthidqieelvdeghedtieegqddujeejke ehheehvddqsghoqhhunhdrfhgvnhhgpeepghhmrghilhdrtghomhesfhhigihmvgdrnhgr mhgvnecuvehluhhsthgvrhfuihiivgeptd X-ME-Proxy: Received: from localhost (unknown [45.32.128.109]) by mail.messagingengine.com (Postfix) with ESMTPA id 5A93A380085; Mon, 5 Aug 2019 10:43:23 -0400 (EDT) Date: Mon, 5 Aug 2019 22:43:18 +0800 From: Boqun Feng To: Peter Zijlstra Cc: Oleg Nesterov , Will Deacon , Ingo Molnar , Thomas Gleixner , linux-kernel@vger.kernel.org, bigeasy@linutronix.de, juri.lelli@redhat.com, williams@redhat.com, bristot@redhat.com, longman@redhat.com, dave@stgolabs.net, jack@suse.com Subject: Re: [PATCH] locking/percpu_rwsem: Rewrite to not use rwsem Message-ID: <20190805144318.GA972@tardis> References: <20190805140241.GI2332@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="vkogqOf2sHV7VnPd" Content-Disposition: inline In-Reply-To: <20190805140241.GI2332@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --vkogqOf2sHV7VnPd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Aug 05, 2019 at 04:02:41PM +0200, Peter Zijlstra wrote: [...] > =20 > static inline void percpu_up_read(struct percpu_rw_semaphore *sem) > { > + rwsem_release(&sem->dep_map, 1, _RET_IP_); > + > preempt_disable(); > /* > * Same as in percpu_down_read(). > */ > - if (likely(rcu_sync_is_idle(&sem->rss))) > + if (likely(rcu_sync_is_idle(&sem->rss))) { > __this_cpu_dec(*sem->read_count); > - else > - __percpu_up_read(sem); /* Unconditional memory barrier */ > - preempt_enable(); > + preempt_enable(); > + return; > + } > =20 > - rwsem_release(&sem->rw_sem.dep_map, 1, _RET_IP_); Missing a preempt_enable() here? Regards, Boqun > + __percpu_up_read(sem); /* Unconditional memory barrier */ > } > =20 [...] --vkogqOf2sHV7VnPd Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEj5IosQTPz8XU1wRHSXnow7UH+rgFAl1IQIIACgkQSXnow7UH +riYhwgArXXexCI0Q1tAuo22Sm/mIuybM3hwoFeONPNiLj0lk2CkxXgk+pjpJ0e8 jBzEkvDXllSIuEbpNwYo7fsyPgR6Bz7+Pgt/H3ntOXDENpsIFyqTPXlI2yPixIwc 7YQey4/qPlLXxG/8lQl7KjZSWTMLcC3rTpLXzOr5jOiOKrnWAZ2jIs+LiGJxnON8 dZT0jo21LEDh1cgj85rxplP7mh4OFoPvGkdzSxm0hGe22Jk96lTyw/WV0BpnQkWw q7i7n4lLtJGuzTSKxu2ulonLUI9mGBZeh+PXBPqMUSvuxQIJ6fywe3p5TpGXsjn0 KFgxmj77SKhuj+zFwdMMzWwgGGxkPg== =iaEy -----END PGP SIGNATURE----- --vkogqOf2sHV7VnPd--