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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0035EC433EF for ; Fri, 20 May 2022 23:30:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354083AbiETXaX (ORCPT ); Fri, 20 May 2022 19:30:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229733AbiETXaU (ORCPT ); Fri, 20 May 2022 19:30:20 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DC0251A6ADF; Fri, 20 May 2022 16:30:18 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6C83461E4A; Fri, 20 May 2022 23:30:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97C0FC385A9; Fri, 20 May 2022 23:30:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1653089417; bh=P2DRkR32s1NsMQQYdV69P9AP9FWKxnSxvUzmxP2UTfM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LFVuDPyLOIgq5/gp0vFI0m4iG1e6x7YD5eJ2kPMDn/VIcatZdMgpdluKZy2mBMZtX knxjLbbEso3dCFrNebOOFKdAI8LwT4dJgGhOJm0J9UDgxgEz0TEd6Jbl2o+xbR3CUS 25aFWx7YU6EJrRjgiTdkw6hIHgKn4pMbqEhrnhPT3lr1XZem18X+i9CJYpSUqAo2MR lSj3XRTDdBM2zh5y66b3X4FnmTZdSgYfXMYP341H0lCORsBOqduq79NwUbybfr11V8 8W6wKgpEo+Jk4S0RbRD+kqLMWsMdtEdrl2+TNQ53v8kkyvD4do9AgaQYwRbchQS+wS p3UuzRLAmIJEw== Date: Fri, 20 May 2022 16:30:14 -0700 From: Nathan Chancellor To: Saravana Kannan Cc: Jonathan Corbet , Greg Kroah-Hartman , "Rafael J. Wysocki" , "Rafael J. Wysocki" , Rob Herring , Linus Walleij , Will Deacon , Ulf Hansson , Kevin Hilman , Thierry Reding , Mark Brown , Pavel Machek , Geert Uytterhoeven , Yoshihiro Shimoda , Paul Kocialkowski , linux-gpio@vger.kernel.org, linux-pm@vger.kernel.org, iommu@lists.linux-foundation.org, kernel-team@android.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v1] driver core: Extend deferred probe timeout on driver registration Message-ID: References: <20220429220933.1350374-1-saravanak@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220429220933.1350374-1-saravanak@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org Hi Saravana, On Fri, Apr 29, 2022 at 03:09:32PM -0700, Saravana Kannan wrote: > The deferred probe timer that's used for this currently starts at > late_initcall and runs for driver_deferred_probe_timeout seconds. The > assumption being that all available drivers would be loaded and > registered before the timer expires. This means, the > driver_deferred_probe_timeout has to be pretty large for it to cover the > worst case. But if we set the default value for it to cover the worst > case, it would significantly slow down the average case. For this > reason, the default value is set to 0. > > Also, with CONFIG_MODULES=y and the current default values of > driver_deferred_probe_timeout=0 and fw_devlink=on, devices with missing > drivers will cause their consumer devices to always defer their probes. > This is because device links created by fw_devlink defer the probe even > before the consumer driver's probe() is called. > > Instead of a fixed timeout, if we extend an unexpired deferred probe > timer on every successful driver registration, with the expectation more > modules would be loaded in the near future, then the default value of > driver_deferred_probe_timeout only needs to be as long as the worst case > time difference between two consecutive module loads. > > So let's implement that and set the default value to 10 seconds when > CONFIG_MODULES=y. > > Cc: Greg Kroah-Hartman > Cc: "Rafael J. Wysocki" > Cc: Rob Herring > Cc: Linus Walleij > Cc: Will Deacon > Cc: Ulf Hansson > Cc: Kevin Hilman > Cc: Thierry Reding > Cc: Mark Brown > Cc: Pavel Machek > Cc: Geert Uytterhoeven > Cc: Yoshihiro Shimoda > Cc: Paul Kocialkowski > Cc: linux-gpio@vger.kernel.org > Cc: linux-pm@vger.kernel.org > Cc: iommu@lists.linux-foundation.org > Signed-off-by: Saravana Kannan I bisected a boot hang with ARCH=s390 defconfig in QEMU down to this change as commit 2b28a1a84a0e ("driver core: Extend deferred probe timeout on driver registration") in next-20220520 (bisect log below). $ make -skj"$(nproc)" ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- defconfig bzImage $ timeout --foreground 15m stdbuf -oL -eL \ qemu-system-s390x \ -initrd ... \ -M s390-ccw-virtio \ -display none \ -kernel arch/s390/boot/bzImage \ -m 512m \ -nodefaults \ -serial mon:stdio ... [ 2.077303] In-situ OAM (IOAM) with IPv6 [ 2.077639] NET: Registered PF_PACKET protocol family [ 2.078063] bridge: filtering via arp/ip/ip6tables is no longer available by default. Update your scripts to load br_netfilter if you need this. [ 2.078795] Key type dns_resolver registered [ 2.079317] cio: Channel measurement facility initialized using format extended (mode autodetected) [ 2.081494] Discipline DIAG cannot be used without z/VM [ 260.626363] random: crng init done qemu-system-s390x: terminating on signal 15 from pid 3815762 (timeout) We have a simple rootfs available if necessary: https://github.com/ClangBuiltLinux/boot-utils/raw/bc0d17785eb67f1edd0ee0a134970a807895f741/images/s390/rootfs.cpio.zst If there is any other information I can provide, please let me know! Cheers, Nathan # bad: [18ecd30af1a8402c162cca1bd58771c0e5be7815] Add linux-next specific files for 20220520 # good: [b015dcd62b86d298829990f8261d5d154b8d7af5] Merge tag 'for-5.18/parisc-4' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux git bisect start '18ecd30af1a8402c162cca1bd58771c0e5be7815' 'b015dcd62b86d298829990f8261d5d154b8d7af5' # good: [f9b63740b666dd9887eb0282d21b5f65bb0cadd0] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git git bisect good f9b63740b666dd9887eb0282d21b5f65bb0cadd0 # good: [1f5eb3e76303572f0318e8c50da51c516580aa03] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git git bisect good 1f5eb3e76303572f0318e8c50da51c516580aa03 # bad: [4c1d9cc0363691893ef94fa0d798faca013e27d3] Merge branch 'staging-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git git bisect bad 4c1d9cc0363691893ef94fa0d798faca013e27d3 # bad: [dcb68304485c0ba5f84f1a54687c751b68263d93] Merge branch 'usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial.git git bisect bad dcb68304485c0ba5f84f1a54687c751b68263d93 # good: [61271996dc46aecb40fd26f89a4ec0a6bd8f3a8f] Merge branch 'next' of git://git.kernel.org/pub/scm/virt/kvm/kvm.git git bisect good 61271996dc46aecb40fd26f89a4ec0a6bd8f3a8f # good: [d4db45a71f56032b552e161968bb0e5fdd2767f8] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/pavel/linux-leds.git git bisect good d4db45a71f56032b552e161968bb0e5fdd2767f8 # good: [d090c7a2ab84663185e4abda21d7d83880937c8a] USB / dwc3: Fix a checkpatch warning in core.c git bisect good d090c7a2ab84663185e4abda21d7d83880937c8a # bad: [b232b02bf3c205b13a26dcec08e53baddd8e59ed] driver core: fix deadlock in __device_attach git bisect bad b232b02bf3c205b13a26dcec08e53baddd8e59ed # good: [4c32174a24759d5ac6dc42b508fcec2afb8b9602] Documentation: dd: Use ReST lists for return values of driver_deferred_probe_check_state() git bisect good 4c32174a24759d5ac6dc42b508fcec2afb8b9602 # good: [38ea74eb8fc1b82b39e13a6527095a0036539117] rpmsg: use local 'dev' variable git bisect good 38ea74eb8fc1b82b39e13a6527095a0036539117 # good: [1f7ff11ca68f464b6a9a71b8fbe9e5219e7cac57] driver core: location: Add "back" as a possible output for panel git bisect good 1f7ff11ca68f464b6a9a71b8fbe9e5219e7cac57 # good: [6ee60e9c9f2f83ad218159af6a175c57a395ae69] MAINTAINERS: add Russ Weight as a firmware loader maintainer git bisect good 6ee60e9c9f2f83ad218159af6a175c57a395ae69 # bad: [15f214f9bdb7c1f560b4bf863c5a72ff53b442a4] topology: Remove unused cpu_cluster_mask() git bisect bad 15f214f9bdb7c1f560b4bf863c5a72ff53b442a4 # bad: [2b28a1a84a0eb3412bad1a2d5cce2bb4addec626] driver core: Extend deferred probe timeout on driver registration git bisect bad 2b28a1a84a0eb3412bad1a2d5cce2bb4addec626 # first bad commit: [2b28a1a84a0eb3412bad1a2d5cce2bb4addec626] driver core: Extend deferred probe timeout on driver registration