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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 22AD5C433EF for ; Tue, 26 Apr 2022 01:45:30 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4KnPpc4C33z3bdF for ; Tue, 26 Apr 2022 11:45:28 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=Zr8atUaF; dkim-atps=neutral Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4KnPnp7535z3bd5 for ; Tue, 26 Apr 2022 11:44:46 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=Zr8atUaF; dkim-atps=neutral Received: by gandalf.ozlabs.org (Postfix) id 4KnPnh5mdZz4xXW; Tue, 26 Apr 2022 11:44:40 +1000 (AEST) Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4KnPnh4D6sz4x7Y; Tue, 26 Apr 2022 11:44:40 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1650937480; bh=VWyDU9G1Ur3JeP1x185c703CLWEY3sKF7Usq0hxceTw=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=Zr8atUaFLZ+IbyopYD0sGRI9OT3WMvUX6RDzLQn4zd0BVsmS4j83cockIHZ7lTEAo TS5vdTth0o6DPUhIvHx07Gfem5Pw01WAXrIxEaE/hiToXKHVPLQLTcu2zeCr63t+mx F8MfQokm7klnTY5KSe5iq0eolz7sF1CbmwOj5kw1V9AsHBGQjaIDcBEFsUyCaqR3ke JYUxR9reIBbn8XpBc0HixetsF9Dig8yvOnkb8qZZIoKqtnSI6fTW8XEsu2rIxe+PKh ZdZ2AVKmhyJx0qszKC3jbUAROjT63XNcmtSdBxYaISP2Uzq4RPJ66KxG4rdDOVhA/f m4qNwruSIFcTg== From: Michael Ellerman To: Nathan Lynch , Mahesh Salgaonkar Subject: Re: [PATCH v5] PCI hotplug: rpaphp: Error out on busy status from get-sensor-state In-Reply-To: <877d7crdn7.fsf@linux.ibm.com> References: <164684593617.368427.2230609269419942906.stgit@jupiter> <877d7crdn7.fsf@linux.ibm.com> Date: Tue, 26 Apr 2022 11:44:36 +1000 Message-ID: <87ee1k8vp7.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tyrel Datwyler , Oliver O'Halloran , linuxppc-dev Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Nathan Lynch writes: > Mahesh Salgaonkar writes: >> When certain PHB HW failure causes phyp to recover PHB, it marks the PE >> state as temporarily unavailable until recovery is complete. This also >> triggers an EEH handler in Linux which needs to notify drivers, and perform >> recovery. But before notifying the driver about the pci error it uses PCI >> get_adapter_state()->get-sesnor-state() operation of the hotplug_slot to ^ typo >> determine if the slot contains a device or not. if the slot is empty, the >> recovery is skipped entirely. >> >> However on certain PHB failures, the rtas call get-sesnor-state() returns ^ typo >> extended busy error (9902) until PHB is recovered by phyp. Once PHB is >> recovered, the get-sensor-state() returns success with correct presence >> status. The rtas call interface rtas_get_sensor() loops over the rtas call RTAS >> on extended delay return code (9902) until the return value is either >> success (0) or error (-1). This causes the EEH handler to get stuck for ~6 >> seconds before it could notify that the pci error has been detected and >> stop any active operations. Hence with running I/O traffic, during this 6 >> seconds, the network driver continues its operation and hits a timeout >> (netdev watchdog). On timeouts, network driver go into ffdc capture mode >> and reset path assuming the PCI device is in fatal condition. This >> sometimes causes EEH recovery to fail. This impacts the ssh connection and >> leads to the system being inaccessible. >> >> ------------ >> [52732.244731] DEBUG: ibm_read_slot_reset_state2() >> [52732.244762] DEBUG: ret = 0, rets[0]=5, rets[1]=1, rets[2]=4000, rets[3]=> >> [52732.244798] DEBUG: in eeh_slot_presence_check >> [52732.244804] DEBUG: error state check >> [52732.244807] DEBUG: Is slot hotpluggable >> [52732.244810] DEBUG: hotpluggable ops ? >> [52732.244953] DEBUG: Calling ops->get_adapter_status >> [52732.244958] DEBUG: calling rpaphp_get_sensor_state >> [52736.564262] ------------[ cut here ]------------ >> [52736.564299] NETDEV WATCHDOG: enP64p1s0f3 (tg3): transmit queue 0 timed o> >> [52736.564324] WARNING: CPU: 1442 PID: 0 at net/sched/sch_generic.c:478 dev> >> [...] >> [52736.564505] NIP [c000000000c32368] dev_watchdog+0x438/0x440 >> [52736.564513] LR [c000000000c32364] dev_watchdog+0x434/0x440 >> ------------ >> >> To avoid this issue, fix the pci hotplug driver (rpaphp) to return an error >> if the slot presence state can not be detected immediately while pe is in PE >> EEH recovery state. Current implementation uses rtas_get_sensor() API which >> blocks the slot check state until rtas call returns success. Change >> rpaphp_get_sensor_state() to invoke rtas_call(get-sensor-state) directly >> only if the respective pe is in EEH recovery state, and take actions based >> on rtas return status. >> >> In normal cases (non-EEH case) rpaphp_get_sensor_state() will continue to >> invoke rtas_get_sensor() as it was earlier with no change in existing >> behavior. >> >> Signed-off-by: Mahesh Salgaonkar >> >> --- >> Change in v5: >> - Fixup #define macros with parentheses around the values. >> >> Change in V4: >> - Error out on sensor busy only if pe is going through EEH recovery instead >> of always error out. >> >> Change in V3: >> - Invoke rtas_call(get-sensor-state) directly from >> rpaphp_get_sensor_state() directly and do special handling. >> - See v2 at >> https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-November/237336.html >> >> Change in V2: >> - Alternate approach to fix the EEH issue instead of delaying slot presence >> check proposed at >> https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-November/236956.html >> >> Also refer: >> https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-November/237027.html > > Sorry for the long delay. I think it looks OK now. Does this need to go > to the PCI list/maintainer? Yes it needs to be Cc'ed to the PCI list/maintainer, even if we end up merging it via the powerpc tree. cheers