From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 5E923A0352; Mon, 14 Feb 2022 19:27:12 +0100 (CET) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id EB0A840DDA; Mon, 14 Feb 2022 19:27:11 +0100 (CET) Received: from mail-108-mta145.mxroute.com (mail-108-mta145.mxroute.com [136.175.108.145]) by mails.dpdk.org (Postfix) with ESMTP id 276704067E for ; Mon, 14 Feb 2022 19:27:09 +0100 (CET) Received: from filter006.mxroute.com ([140.82.40.27] 140.82.40.27.vultr.com) (Authenticated sender: mN4UYu2MZsgR) by mail-108-mta145.mxroute.com (ZoneMTA) with ESMTPSA id 17ef97d0b530005a20.003 for (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES128-GCM-SHA256); Mon, 14 Feb 2022 18:27:08 +0000 X-Zone-Loop: 3be732ebf2631c0f79723ee1f38004ef9467ce1b4615 X-Originating-IP: [140.82.40.27] DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=ashroe.eu; s=x; h=Content-Type:MIME-Version:Message-ID:Date:In-reply-to:Subject:Cc:To: From:References:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=dQvP3Rdgb8YZSo6FF4IyeSeKV5wkdxPVsxoHeNzf1iU=; b=hpVMpddvAzGz6PjeVh5dbRxG8y 4TlYsQWVzn7OI6cOVP34nyMzKSvmUASv0L/AmgYEq76Rw5rO7qqvMfYFINcYWsQXPz2Msri+qC/CV 5yqPYokpV1rh+kqDdLiFc7d6BEl7GwXdTUSBzTRT43OC8uv7MuMUZpGJNxBtGJEaQEKEyPBrWAPxX xzEFE1N6VP3RkcjVx55bvrdfMQoLOG36GvML8tyyzvs/fQjasGGozx3RvDiYFqqKNlJ4RFPv6k4mB WeI3WSjxoJWCcS/aWVRZf2H/RzHJVDSgan6zCytU2IbggziGvjggbYPlYtglZ39E7FIasdMUAlvAu INNOmD2g==; References: <20201009034832.10302-1-kalesh-anakkur.purayil@broadcom.com> <45691978.XUcTiDjVJD@thomas> <875yphigb6.fsf@mdr78.vserver.site> <3365765.som1txNFv6@thomas> User-agent: mu4e 1.4.15; emacs 27.1 From: Ray Kinsella To: Thomas Monjalon Cc: Ferruh Yigit , Kalesh A P , dev@dpdk.org, ajit.khaparde@broadcom.com, asafp@nvidia.com, David Marchand , Andrew Rybchenko Subject: Re: [dpdk-dev] [PATCH v7 1/4] ethdev: support device reset and recovery events In-reply-to: <3365765.som1txNFv6@thomas> Date: Mon, 14 Feb 2022 13:27:04 -0500 Message-ID: <8735kli9s7.fsf@mdr78.vserver.site> MIME-Version: 1.0 Content-Type: text/plain X-AuthUser: mdr@ashroe.eu X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Thomas Monjalon writes: > 14/02/2022 17:06, Ray Kinsella: >> Thomas Monjalon writes: >> > 14/02/2022 11:16, Ray Kinsella: >> >> Ray Kinsella writes: >> >> > Thomas Monjalon writes: >> >> >> 02/02/2022 12:44, Ray Kinsella: >> >> >>> Ferruh Yigit writes: >> >> >>> > On 1/28/2022 12:48 PM, Kalesh A P wrote: >> >> >>> >> --- a/lib/ethdev/rte_ethdev.h >> >> >>> >> +++ b/lib/ethdev/rte_ethdev.h >> >> >>> >> @@ -3818,6 +3818,24 @@ enum rte_eth_event_type { >> >> >>> >> RTE_ETH_EVENT_DESTROY, /**< port is released */ >> >> >>> >> RTE_ETH_EVENT_IPSEC, /**< IPsec offload related event */ >> >> >>> >> RTE_ETH_EVENT_FLOW_AGED,/**< New aged-out flows is detected */ >> >> >>> >> + RTE_ETH_EVENT_ERR_RECOVERING, >> >> >>> >> + /**< port recovering from an error >> >> >>> >> + * >> >> >>> >> + * PMD detected a FW reset or error condition. >> >> >>> >> + * PMD will try to recover from the error. >> >> >>> >> + * Data path may be quiesced and Control path operations >> >> >>> >> + * may fail at this time. >> >> >>> >> + */ >> >> >>> >> + RTE_ETH_EVENT_RECOVERED, >> >> >>> >> + /**< port recovered from an error >> >> >>> >> + * >> >> >>> >> + * PMD has recovered from the error condition. >> >> >>> >> + * Control path and Data path are up now. >> >> >>> >> + * PMD re-configures the port to the state prior to the error. >> >> >>> >> + * Since the device has undergone a reset, flow rules >> >> >>> >> + * offloaded prior to reset may be lost and >> >> >>> >> + * the application should recreate the rules again. >> >> >>> >> + */ >> >> >>> >> RTE_ETH_EVENT_MAX /**< max value of this enum */ >> >> >>> > >> >> >>> > >> >> >>> > Also ABI check complains about 'RTE_ETH_EVENT_MAX' value check, cc'ed more people >> >> >>> > to evaluate if it is a false positive: >> >> >>> > >> >> >>> > >> >> >>> > 1 function with some indirect sub-type change: >> >> >>> > [C] 'function int rte_eth_dev_callback_register(uint16_t, rte_eth_event_type, rte_eth_dev_cb_fn, void*)' at rte_ethdev.c:4637:1 has some indirect sub-type changes: >> >> >>> > parameter 3 of type 'typedef rte_eth_dev_cb_fn' has sub-type changes: >> >> >>> > underlying type 'int (typedef uint16_t, enum rte_eth_event_type, void*, void*)*' changed: >> >> >>> > in pointed to type 'function type int (typedef uint16_t, enum rte_eth_event_type, void*, void*)': >> >> >>> > parameter 2 of type 'enum rte_eth_event_type' has sub-type changes: >> >> >>> > type size hasn't changed >> >> >>> > 2 enumerator insertions: >> >> >>> > 'rte_eth_event_type::RTE_ETH_EVENT_ERR_RECOVERING' value '11' >> >> >>> > 'rte_eth_event_type::RTE_ETH_EVENT_RECOVERED' value '12' >> >> >>> > 1 enumerator change: >> >> >>> > 'rte_eth_event_type::RTE_ETH_EVENT_MAX' from value '11' to '13' at rte_ethdev.h:3807:1 >> >> >>> >> >> >>> I don't immediately see the problem that this would cause. >> >> >>> There are no array sizes etc dependent on the value of MAX for instance. >> >> >>> >> >> >>> Looks safe? >> >> >> >> >> >> We never know how this enum will be used by the application. >> >> >> The max value may be used for the size of an event array. >> >> >> It looks a real ABI issue unfortunately. >> >> > >> >> > Right - but we only really care about it when an array size based on MAX >> >> > is likely to be passed to DPDK, which doesn't apply in this case. >> > >> > I don't completely agree. >> > A developer may assume an event will never exceed MAX value. >> > However, after an upgrade of DPDK without app rebuild, >> > a higher event value may be received in the app, >> > breaking the assumption. >> > Should we consider this case as an ABI breakage? >> >> Nope - I think we should explicitly exclude MAX values from any >> ABI guarantee, as being able to change them is key to our be able to >> evolve DPDK while maintaining ABI stability. > > Or we can simply remove the MAX values so there is no confusion. > >> Consider what it means applying the ABI policy to a MAX value, you are >> in effect saying that that no value can be added to this enumeration >> until the next ABI version, for me this is very restrictive without a >> solid reason. > > I agree it is too much restrictive, that's why I am advocating > for their removal. I think that would be simplest yes - may require some rework of the sample code though. I will take a look at it. > >> >> > I noted that some Linux folks explicitly mark similar MAX values as not >> >> > part of the ABI. >> >> > >> >> > /usr/include/linux/perf_event.h >> >> > 37: PERF_TYPE_MAX, /* non-ABI */ >> >> > 60: PERF_COUNT_HW_MAX, /* non-ABI */ >> >> > 79: PERF_COUNT_HW_CACHE_MAX, /* non-ABI */ >> >> > 87: PERF_COUNT_HW_CACHE_OP_MAX, /* non-ABI */ >> >> > 94: PERF_COUNT_HW_CACHE_RESULT_MAX, /* non-ABI */ >> >> > 116: PERF_COUNT_SW_MAX, /* non-ABI */ >> >> > 149: PERF_SAMPLE_MAX = 1U << 24, /* non-ABI */ >> >> > 151: __PERF_SAMPLE_CALLCHAIN_EARLY = 1ULL << 63, /* >> >> > non-ABI; internal use */ >> >> > 189: PERF_SAMPLE_BRANCH_MAX_SHIFT /* non-ABI */ >> >> > 267: PERF_TXN_MAX = (1 << 8), /* non-ABI */ >> >> > 301: PERF_FORMAT_MAX = 1U << 4, /* non-ABI */ >> >> > 1067: PERF_RECORD_MAX, /* non-ABI */ >> >> > 1078: PERF_RECORD_KSYMBOL_TYPE_MAX /* non-ABI */ >> >> > 1087: PERF_BPF_EVENT_MAX, /* non-ABI */ >> >> >> >> Any thoughts on similarly annotating all our _MAX enums in the same way? >> >> We could also add a section in the ABI Policy to make it explicit _MAX >> >> enum values are not part of the ABI - what do folks think? >> > >> > Interesting. I am not sure it is always ABI-safe though. -- Regards, Ray K