From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD9ACCA9EBC for ; Wed, 23 Oct 2019 20:17:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 850832064A for ; Wed, 23 Oct 2019 20:17:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hX4nfgmH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403842AbfJWURT (ORCPT ); Wed, 23 Oct 2019 16:17:19 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:23858 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2391642AbfJWURT (ORCPT ); Wed, 23 Oct 2019 16:17:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1571861837; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=oeW+VmP3QU4FevcRW4lhlaqjbMpXhUTeOjj1aJjNG14=; b=hX4nfgmH3kGFD2yDsyE7PIQwJhzp9XGz2CeI8JM0IhcBvTkF2ehW2hjo9gfqY5pfYoNMXx xQ47O8XW7g45yLMH1tyZoz7XUXTIXtc3xCZyhELHM06UvvBR0ZwnH/dN9UFCjiEUX5/NoY 2aAo02RxAEpIV1/KtdY4N8EaoFb2N/Q= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-193-7oQmPxgHOp-fA6EnANPl_g-1; Wed, 23 Oct 2019 16:17:13 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C970E5E4; Wed, 23 Oct 2019 20:17:08 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-121-40.rdu2.redhat.com [10.10.121.40]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8518C5D6D0; Wed, 23 Oct 2019 20:17:05 +0000 (UTC) Subject: [RFC PATCH 00/10] pipe: Notification queue preparation [ver #2] From: David Howells To: torvalds@linux-foundation.org Cc: dhowells@redhat.com, Rasmus Villemoes , Greg Kroah-Hartman , Peter Zijlstra , nicolas.dichtel@6wind.com, raven@themaw.net, Christian Brauner , dhowells@redhat.com, keyrings@vger.kernel.org, linux-usb@vger.kernel.org, linux-block@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 23 Oct 2019 21:17:04 +0100 Message-ID: <157186182463.3995.13922458878706311997.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: 7oQmPxgHOp-fA6EnANPl_g-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: Here's a set of preparatory patches for building a general notification queue on top of pipes. It makes a number of significant changes: (1) It removes the nr_exclusive argument from __wake_up_sync_key() as this is always 1. This prepares for step 2. (2) Adds wake_up_interruptible_sync_poll_locked() so that poll can be woken up from a function that's holding the poll waitqueue spinlock. (3) Change the pipe buffer ring to be managed in terms of unbounded head and tail indices rather than bounded index and length. This means that reading the pipe only needs to modify one index, not two. (4) A selection of helper functions are provided to query the state of the pipe buffer, plus a couple to apply updates to the pipe indices. (5) The pipe ring is allowed to have kernel-reserved slots. This allows many notification messages to be spliced in by the kernel without allowing userspace to pin too many pages if it writes to the same pipe. (6) Advance the head and tail indices inside the pipe waitqueue lock and use step 2 to poke poll without having to take the lock twice. (7) Rearrange pipe_write() to preallocate the buffer it is going to write into and then drop the spinlock. This allows kernel notifications to then be added the ring whilst it is filling the buffer it allocated. The read side is stalled because the pipe mutex is still held. (8) Don't wake up readers on a pipe if there was already data in it when we added more. (9) Don't wake up writers on a pipe if the ring wasn't full before we removed a buffer. The patches can be found here also: =09http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h= =3Dpipe-experimental PATCHES=09BENCHMARK=09BEST=09=09TOTAL BYTES=09AVG BYTES=09STDDEV =3D=3D=3D=3D=3D=3D=3D=09=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=09=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=09=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=09=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=09=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D -=09pipe=09=09 307457969=09 36348556755=09 302904639=09 = 10622403 -=09splice=09=09 287117614=09 26933658717=09 224447155=09 = 160777958 -=09vmsplice=09 435180375=09 51302964090=09 427524700=09 = 19083037 rm-nrx=09pipe=09=09 311091179=09 37093181356=09 309109844=09 = 7221622 rm-nrx=09splice=09=09 285628049=09 27916298942=09 232635824=09= 158296431 rm-nrx=09vmsplice=09 417703153=09 47570362546=09 396419687=09 = 33960822 wakesl=09pipe=09=09 310698731=09 36772541631=09 306437846=09 = 8249347 wakesl=09splice=09=09 286193726=09 28600435451=09 238336962=09= 141169318 wakesl=09vmsplice=09 436175803=09 50723895824=09 422699131=09 = 40724240 ht=09pipe=09=09 305534565=09 36426079543=09 303550662=09 = 5673885 ht=09splice=09=09 243632025=09 23319439010=09 194328658=09 = 150479853 ht=09vmsplice=09 432825176=09 49101781001=09 409181508=09 = 44102509 k-rsv=09pipe=09=09 308691523=09 36652267561=09 305435563=09 = 12972559 k-rsv=09splice=09=09 244793528=09 23625172865=09 196876440=09 = 125319143 k-rsv=09vmsplice=09 436119082=09 49460808579=09 412173404=09 = 55547525 r-adv-t=09pipe=09=09 310094218=09 36860182219=09 307168185=09 = 8081101 r-adv-t=09splice=09=09 285527382=09 27085052687=09 225708772= =09 206918887 r-adv-t=09vmsplice=09 336885948=09 40128756927=09 334406307=09= 5895935 r-cond=09pipe=09=09 308727804=09 36635828180=09 305298568=09 = 9976806 r-cond=09splice=09=09 284467568=09 28445793054=09 237048275=09= 200284329 r-cond=09vmsplice=09 449679489=09 51134833848=09 426123615=09 = 66790875 w-preal=09pipe=09=09 307416578=09 36662086426=09 305517386=09 = 6216663 w-preal=09splice=09=09 282655051=09 28455249109=09 237127075= =09 194154549 w-preal=09vmsplice=09 437002601=09 47832160621=09 398601338=09= 96513019 w-redun=09pipe=09=09 307279630=09 36329750422=09 302747920=09 = 8913567 w-redun=09splice=09=09 284324488=09 27327152734=09 227726272= =09 219735663 w-redun=09vmsplice=09 451141971=09 51485257719=09 429043814=09= 51388217 w-ckful=09pipe=09=09 305055247=09 36374947350=09 303124561=09 = 5400728 w-ckful=09splice=09=09 281575308=09 26841554544=09 223679621= =09 215942886 w-ckful=09vmsplice=09 436653588=09 47564907110=09 396374225=09= 82255342 The patches column indicates the point in the patchset at which the benchma= rks were taken: =090=09No patches =09rm-nrx=09"Remove the nr_exclusive argument from __wake_up_sync_key()" =09wakesl=09"Add wake_up_interruptible_sync_poll_locked()" =09ht=09"pipe: Use head and tail pointers for the ring, not cursor and leng= th" =09k-rsv=09"pipe: Allow pipes to have kernel-reserved slots" =09r-adv-t=09"pipe: Advance tail pointer inside of wait spinlock in pipe_re= ad()" =09r-cond=09"pipe: Conditionalise wakeup in pipe_read()" =09w-preal=09"pipe: Rearrange sequence in pipe_write() to preallocate slot" =09w-redun=09"pipe: Remove redundant wakeup from pipe_write()" =09w-ckful=09"pipe: Check for ring full inside of the spinlock in pipe_writ= e()" Changes: ver #2: (*) Split the notification patches out into a separate branch. (*) Removed the nr_exclusive parameter from __wake_up_sync_key(). (*) Renamed the locked wakeup function. (*) Add helpers for empty, full, occupancy. (*) Split the addition of ->max_usage out into its own patch. (*) Fixed some bits pointed out by Rasmus Villemoes. ver #1: (*) Build on top of standard pipes instead of having a driver. David --- David Howells (10): pipe: Reduce #inclusion of pipe_fs_i.h Remove the nr_exclusive argument from __wake_up_sync_key() Add wake_up_interruptible_sync_poll_locked() pipe: Use head and tail pointers for the ring, not cursor and length pipe: Allow pipes to have kernel-reserved slots pipe: Advance tail pointer inside of wait spinlock in pipe_read() pipe: Conditionalise wakeup in pipe_read() pipe: Rearrange sequence in pipe_write() to preallocate slot pipe: Remove redundant wakeup from pipe_write() pipe: Check for ring full inside of the spinlock in pipe_write() fs/exec.c | 1=20 fs/fuse/dev.c | 31 +++-- fs/ocfs2/aops.c | 1=20 fs/pipe.c | 225 ++++++++++++++++++++++--------------- fs/splice.c | 188 +++++++++++++++++++------------ include/linux/pipe_fs_i.h | 90 ++++++++++++++- include/linux/uio.h | 4 - include/linux/wait.h | 11 +- kernel/exit.c | 2=20 kernel/sched/wait.c | 37 ++++-- lib/iov_iter.c | 266 +++++++++++++++++++++++++---------------= ---- security/smack/smack_lsm.c | 1=20 12 files changed, 541 insertions(+), 316 deletions(-)