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 smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 D2B0AE77197 for ; Tue, 7 Jan 2025 14:00:24 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 69F9A81453; Tue, 7 Jan 2025 14:00:24 +0000 (UTC) X-Virus-Scanned: amavis at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavis, port 10024) with ESMTP id E-tBGCgSSh6X; Tue, 7 Jan 2025 14:00:23 +0000 (UTC) X-Comment: SPF check N/A for local connections - client-ip=140.211.166.142; helo=lists1.osuosl.org; envelope-from=intel-wired-lan-bounces@osuosl.org; receiver= DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org CBCB4814AB DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osuosl.org; s=default; t=1736258423; bh=cct8mjPuTS2g1hERdmr1jNSJDlrhhPaqQc2wki1mp24=; h=Date:From:To:Cc:References:In-Reply-To:Subject:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=IsfabSWQb8UC+ditIFxO6gyudpCLzgrIFY6zIivt04gtMXeTahmHeq8spDxz+TCyy fYnL5wZX+bAkQs2Fh8TtIbC1/8/2UIJuwr+e3j/DZRhWy9K/UZ5jIOhySZDWWG72e/ pd+uxOx7Xxx3cnw5IRPpkPRme8N7wj8ifjHYvgmaJpwrpIwK0lRLc2qGh6jgcnaFck MsaTYarDWS0ZBI/gnbVirlMEX90wEvtax4x/wGwFR+g3x1wEO+i8OMDpRjcrPuQB+f IX4ukbdbMAM/iP7TFnXRp+1e5tW0Aqyt1u3cdRfv57dctq4xfZo7d7mp6OU+bskXX4 5oNlA9Wiwy4mQ== Received: from lists1.osuosl.org (lists1.osuosl.org [140.211.166.142]) by smtp1.osuosl.org (Postfix) with ESMTP id CBCB4814AB; Tue, 7 Jan 2025 14:00:23 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists1.osuosl.org (Postfix) with ESMTP id 54F997AA for ; Tue, 7 Jan 2025 14:00:22 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 4323481452 for ; Tue, 7 Jan 2025 14:00:22 +0000 (UTC) X-Virus-Scanned: amavis at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavis, port 10024) with ESMTP id pLUDZATQ4b9r for ; Tue, 7 Jan 2025 14:00:18 +0000 (UTC) X-Greylist: delayed 537 seconds by postgrey-1.37 at util1.osuosl.org; Tue, 07 Jan 2025 14:00:07 UTC DMARC-Filter: OpenDMARC Filter v1.4.2 smtp1.osuosl.org 81DCA81678 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 81DCA81678 Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=2a0a:51c0:0:12e:550::1; helo=galois.linutronix.de; envelope-from=bigeasy@linutronix.de; receiver= Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by smtp1.osuosl.org (Postfix) with ESMTPS id 81DCA81678 for ; Tue, 7 Jan 2025 14:00:07 +0000 (UTC) Date: Tue, 7 Jan 2025 14:51:06 +0100 From: Sebastian Andrzej Siewior To: Wander Lairson Costa Cc: Tony Nguyen , Przemek Kitszel , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Clark Williams , Steven Rostedt , Jeff Garzik , Auke Kok , "moderated list:INTEL ETHERNET DRIVERS" , "open list:NETWORKING DRIVERS" , open list , "open list:Real-time Linux (PREEMPT_RT):Keyword:PREEMPT_RT" Message-ID: <20250107135106.WWrtBMXY@linutronix.de> References: <20241204114229.21452-1-wander@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20241204114229.21452-1-wander@redhat.com> X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1736257868; 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: in-reply-to:in-reply-to:references:references; bh=cct8mjPuTS2g1hERdmr1jNSJDlrhhPaqQc2wki1mp24=; b=IOhx86Esibh8T7Uq3RkbLHC3DioF3Wrh98RsmTDbQA8S6DEUvMNyR/rkleXX1Xa0xSoIg0 Im2GF8dgr0/ARtD0+n7GCXUlzUnLgHzIQCOOa3hlf8ac8o516KXrFXZgM5C1FkQYUIMTQo P55DAIuAcWvJWRM0E2l/P6BRp+G2ojoxa7EJvpVB36U+F/wBmf19Bv5PZOnlUfmk7sfoSz cDd6XqNhYXvLZ8IA93UgD71FLqojCGw7UHxDDqunXbdIV2so0ORCOuz4HI85NrJcgvkrlE mTsMtG6d5pUg2OpqOIEI7LYtT+dICn+rRUKML3cZNUqGNR4fYaW3yQJw9Q/PIA== X-Mailman-Original-DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1736257868; 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: in-reply-to:in-reply-to:references:references; bh=cct8mjPuTS2g1hERdmr1jNSJDlrhhPaqQc2wki1mp24=; b=4knpNCMXSS+IFvgXhM12tf4YO5sC0sRyfIuWp2PqSEy+zyUrQ/71+LYqqZSEEv8ZQ886yE q5lFR933wlWa/ODw== X-Mailman-Original-Authentication-Results: smtp1.osuosl.org; dmarc=pass (p=none dis=none) header.from=linutronix.de X-Mailman-Original-Authentication-Results: smtp1.osuosl.org; dkim=pass (2048-bit key, unprotected) header.d=linutronix.de header.i=@linutronix.de header.a=rsa-sha256 header.s=2020 header.b=IOhx86Es; dkim=pass header.d=linutronix.de header.i=@linutronix.de header.a=ed25519-sha256 header.s=2020e header.b=4knpNCMX Subject: Re: [Intel-wired-lan] [PATCH iwl-net 0/4] igb: fix igb_msix_other() handling for PREEMPT_RT X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" On 2024-12-04 08:42:23 [-0300], Wander Lairson Costa wrote: > This is the second attempt at fixing the behavior of igb_msix_other() > for PREEMPT_RT. The previous attempt [1] was reverted [2] following > concerns raised by Sebastian [3]. > > The initial approach proposed converting vfs_lock to a raw_spinlock, > a minor change intended to make it safe. However, it became evident > that igb_rcv_msg_from_vf() invokes kcalloc with GFP_ATOMIC, > which is unsafe in interrupt context on PREEMPT_RT systems. > > To address this, the solution involves splitting igb_msg_task() > into two parts: > > * One part invoked from the IRQ context. > * Another part called from the threaded interrupt handler. > > To accommodate this, vfs_lock has been restructured into a double > lock: a spinlock_t and a raw_spinlock_t. In the revised design: > > * igb_disable_sriov() locks both spinlocks. > * Each part of igb_msg_task() locks the appropriate spinlock for > its execution context. - Is this limited to PREEMPT_RT or does it also occur on PREEMPT systems with threadirqs? And if this is PREEMPT_RT only, why? - What causes the failure? I see you reworked into two parts to behave similar to what happens without threaded interrupts. There is still no explanation for it. Is there a timing limit or was there another register operation which removed the mailbox message? > Cheers, > Wander Sebastian