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 6405DC4332F for ; Fri, 9 Dec 2022 11:27:15 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4NT7z56LLhz3bfy for ; Fri, 9 Dec 2022 22:27:13 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=A7wHeBhY; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=A7wHeBhY; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=170.10.133.124; helo=us-smtp-delivery-124.mimecast.com; envelope-from=dhowells@redhat.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=A7wHeBhY; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=A7wHeBhY; dkim-atps=neutral Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 4NT7yv49S6z3bXW for ; Fri, 9 Dec 2022 22:27:01 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670585217; 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=Fk6lJ/K747gX2RARMStBT56RkzQK/6QuPSWKbrkfp3w=; b=A7wHeBhY5IjaA2ZTnrM+XeKEn4UzQNMOZW1TwDWTnffdAWyr3YN6VMm9oOlDAlq98JQaro eBSukDOAcAoAuwET/l9HuzTt5YxVBp5IMTDCkwEr0DaFgXqT/YFmiITojI17OBA4aDsH8r utmwoUSB4xUWC7pF13XFNzCdg2MQGQo= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670585217; 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=Fk6lJ/K747gX2RARMStBT56RkzQK/6QuPSWKbrkfp3w=; b=A7wHeBhY5IjaA2ZTnrM+XeKEn4UzQNMOZW1TwDWTnffdAWyr3YN6VMm9oOlDAlq98JQaro eBSukDOAcAoAuwET/l9HuzTt5YxVBp5IMTDCkwEr0DaFgXqT/YFmiITojI17OBA4aDsH8r utmwoUSB4xUWC7pF13XFNzCdg2MQGQo= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-596-bZbAd-KNPDi39SLGApyWzA-1; Fri, 09 Dec 2022 06:26:55 -0500 X-MC-Unique: bZbAd-KNPDi39SLGApyWzA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 26A61185A794; Fri, 9 Dec 2022 11:26:55 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.17]) by smtp.corp.redhat.com (Postfix) with ESMTP id A5FA640C6EC2; Fri, 9 Dec 2022 11:26:53 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <42b33792-50e9-77d7-4d3e-ac5ce1adeda6@huaweicloud.com> References: <42b33792-50e9-77d7-4d3e-ac5ce1adeda6@huaweicloud.com> <20221128031929.3918348-1-houtao@huaweicloud.com> To: Hou Tao Subject: Re: [PATCH] fscache: Use wake_up_var() to wake up pending volume acquisition MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2308528.1670585211.1@warthog.procyon.org.uk> Date: Fri, 09 Dec 2022 11:26:51 +0000 Message-ID: <2308529.1670585211@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jeff Layton , linux-kernel@vger.kernel.org, dhowells@redhat.com, linux-cachefs@redhat.com, "houtao1@huawei.com" , linux-erofs@lists.ozlabs.org Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" Hou Tao wrote: > > clear_bit(FSCACHE_VOLUME_ACQUIRE_PENDING, &cursor->flags); Maybe this should be clear_bit_unlock() instead. And I wonder if: set_bit(FSCACHE_VOLUME_ACQUIRE_PENDING, &candidate->flags); in fscache_hash_volume() needs a barrier before it. > > - wake_up_bit(&cursor->flags, FSCACHE_VOLUME_ACQUIRE_PENDING); > > + /* > > + * Paired with barrier in wait_var_event(). Check > > + * waitqueue_active() and wake_up_var() for details. > > + */ > > + smp_mb__after_atomic(); > > + wake_up_var(&cursor->flags); That doesn't seem right. wake_up_bit() is more selective, so should be preferred to wake_up_var(). David