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=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 22AF1C2BA19 for ; Mon, 6 Apr 2020 13:43:42 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D24352336F for ; Mon, 6 Apr 2020 13:43:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D24352336F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48wsFP3TBpzDqVF for ; Mon, 6 Apr 2020 23:43:37 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 48wrPv5rX2zDr6K for ; Mon, 6 Apr 2020 23:05:55 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Received: by ozlabs.org (Postfix, from userid 1034) id 48wrPr2x9bz9sRY; Mon, 6 Apr 2020 23:05:51 +1000 (AEST) X-powerpc-patch-notification: thanks X-powerpc-patch-commit: abc3fce76adbdfa8f87272c784b388cd20b46049 In-Reply-To: <20200402120401.1115883-1-npiggin@gmail.com> To: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org From: Michael Ellerman Subject: Re: [PATCH] Revert "powerpc/64: irq_work avoid interrupt when called with hardware irqs enabled" Message-Id: <48wrPr2x9bz9sRY@ozlabs.org> Date: Mon, 6 Apr 2020 23:05:51 +1000 (AEST) 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: Nicholas Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, 2020-04-02 at 12:04:01 UTC, Nicholas Piggin wrote: > This reverts commit ebb37cf3ffd39fdb6ec5b07111f8bb2f11d92c5f. > > That commit does not play well with soft-masked irq state manipulations > in idle, interrupt replay, and possibly others due to tracing code > sometimes using irq_work_queue (e.g., in trace_hardirqs_on()). That > can cause PACA_IRQ_DEC to become set when it is not expected, and be > ignored or cleared or cause warnings. > > The net result seems to be missing an irq_work until the next timer > interrupt in the worst case which is usually not going to be noticed, > however it could be a long time if the tick is disabled, which is > agains the spirit of irq_work and might cause real problems. > > The idea is still solid, but it would need more work. It's not really > clear if it would be worth added complexity, so revert this for now > (not a straight revert, but replace with a comment explaining why we > might see interrupts happening, and gives git blame something to find). > > Fixes: ebb37cf3ffd3 ("powerpc/64: irq_work avoid interrupt when called with hardware irqs enabled") > Signed-off-by: Nicholas Piggin Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/abc3fce76adbdfa8f87272c784b388cd20b46049 cheers