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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 65D4FC433DB for ; Mon, 1 Mar 2021 09:30:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22FE864E22 for ; Mon, 1 Mar 2021 09:30:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233878AbhCAJa3 (ORCPT ); Mon, 1 Mar 2021 04:30:29 -0500 Received: from mx1.opensynergy.com ([217.66.60.4]:55665 "EHLO mx1.opensynergy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233934AbhCAJaI (ORCPT ); Mon, 1 Mar 2021 04:30:08 -0500 Received: from SR-MAILGATE-02.opensynergy.com (localhost.localdomain [127.0.0.1]) by mx1.opensynergy.com (Proxmox) with ESMTP id 98005A1340; Mon, 1 Mar 2021 10:29:25 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=opensynergy.com; h=cc:cc:content-transfer-encoding:content-type:content-type :date:from:from:in-reply-to:message-id:mime-version:references :reply-to:subject:subject:to:to; s=srmailgate02; bh=AF2+aLbHpYk6 yxg/KMusF89bfRVX3X9/VCCjZ8mooHU=; b=njrad0q9gBYFdXuKLLKrdMQiJrmC 2BkUzmkCM+/7GTmtBRL4KEei2E9d4aTwbewItdx8ywzFTZ+Wq+o0YIf8ctZOxS6s pWUn/fd83sGZ/mCG1K5YR5fADtw4ahaRbEnXVRkPL6sL2RWJlDxJ4xow1k7GxPEl wsNo0I+0+kfO+5odG3fJVrIfyApV8XWZNWyz1D/U2mYX25e+aY8VQk5NmK18oKUf AXuAStUtmc5vLAuHdldToU4L4wQobXvwR0KNh3CO0PUQIgSbPn1tUFY+nQuOALEY zXBiH5ZcCoYx9U6bwN5/r1O8apbH0HBuDUG76grDuZ0I2zjZIrk1jMc/Zw== Subject: Re: [PATCH v6 6/9] ALSA: virtio: PCM substream operators To: Takashi Iwai CC: , , , "Michael S. Tsirkin" , Jaroslav Kysela , Takashi Iwai , References: <20210227085956.1700687-1-anton.yakovlev@opensynergy.com> <20210227085956.1700687-7-anton.yakovlev@opensynergy.com> From: Anton Yakovlev Message-ID: Date: Mon, 1 Mar 2021 10:29:24 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SR-MAIL-01.open-synergy.com (10.26.10.21) To SR-MAIL-01.open-synergy.com (10.26.10.21) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28.02.2021 12:32, Takashi Iwai wrote: > On Sat, 27 Feb 2021 09:59:53 +0100, > Anton Yakovlev wrote: >> [snip] >> +static snd_pcm_uframes_t >> +virtsnd_pcm_pointer(struct snd_pcm_substream *substream) >> +{ >> + struct virtio_pcm_substream *vss = snd_pcm_substream_chip(substream); >> + snd_pcm_uframes_t hw_ptr = SNDRV_PCM_POS_XRUN; >> + unsigned long flags; >> + >> + spin_lock_irqsave(&vss->lock, flags); >> + if (!vss->xfer_xrun) >> + hw_ptr = bytes_to_frames(substream->runtime, vss->hw_ptr); >> + spin_unlock_irqrestore(&vss->lock, flags); > > Oh, and if we drop nonatomc PCM, both trigger and pointer callbacks > are guaranteed to be called inside the spinlock, hence you can remove > *_irqsave() but just us spin_lock() in those two callbacks. As I understand, spin_lock_irqsave() disables only local interrupts. But what about other CPU cores? > > thanks, > > Takashi > -- Anton Yakovlev Senior Software Engineer OpenSynergy GmbH Rotherstr. 20, 10245 Berlin