From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f177.google.com (mail-qk1-f177.google.com [209.85.222.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2FC871386D1 for ; Thu, 15 Feb 2024 17:47:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708019233; cv=none; b=gwQK62Osc/pgahTWeVQrd/TBNRKJchhNJn0CYxoT4Vgw1AkBViQPAKakVuAVVzoifAm5nW4SkiEnJ7H8kvBCKAPN9VVGwAyIDO9Z7zMYtD1egd1O+Xdb41QNY4rUYmmaDbdsANoBX0tmArOoNZYwT3JVM4hLSetNvOyz+5HLm7g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708019233; c=relaxed/simple; bh=+dXm83v4lzGGGWoMkrAhpsoKvqPYYTZkbg+SCOnXjxY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bJyaFwHlOOsH2UWQKMHbeHfR0sa3xKMsk/UP5rsw+2kb0V6httePqc9iF8vCz0S86JKo3Hd45FBYn/U+BEE9vJaxvJ/og3zlGyKECb2DBKB1jKap9zGCaca6aS/DCoyJRKUU23uBmMFaXeJwrf1kxtYxBs3ra3o4VjhBBzezcuI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca; spf=pass smtp.mailfrom=ziepe.ca; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b=Qo9bxomr; arc=none smtp.client-ip=209.85.222.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ziepe.ca Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="Qo9bxomr" Received: by mail-qk1-f177.google.com with SMTP id af79cd13be357-785d5705681so111745185a.1 for ; Thu, 15 Feb 2024 09:47:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1708019230; x=1708624030; darn=lists.linux.dev; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=gwxKYOTTfsVxRUkOMJlptUV0ZFZUoBorwA6GkU+MTmM=; b=Qo9bxomr1W0+GHP1ApUr5sKNO/qqg2b8mLTh15ftGQ8VkiMxjTJ19k2fMJNJbbJTNu TffDfS5JmQfz4KCl4VuRIc3REf7p23qxkFCsSkmDaRT62WUIpl0N8TFe1OB8iT0GAAtf HGNXg+JUMHcVEQHd8Hsk8oCutkX5wGJ+GSgBtBa37SQSfAnTXbtiQqqiNs0FuqnTfphT 6rur1xgI0bA7N0vVSJJM2im1lKsExYulq1StgtTLY3QgO8Y6fLtliJfJP241GAEOxNk6 l+nbZMTA2Du9RWO+n1Cfg8eK5s7f5/YLDCXNnSjsvAvQpmlTlNDQcKWUWLGP/SAiBIQY oj/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708019230; x=1708624030; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=gwxKYOTTfsVxRUkOMJlptUV0ZFZUoBorwA6GkU+MTmM=; b=vqUigka/jufMExLGoRYikmplCxD+pvOwL26cdlD6XnuHdz08qTUzQEwaOX6SeWRor5 jjNInPWuoHIxfOAmqWHvf9UPHIko4sbA+kTO7wMHqmLOcofxqA5LQhwWEVy57BqAESjJ XwAdwc7V2Lvs4mj7pNhWiJnn5Yi1tX4HzLIM7K2+t3oqVGXyjqYVuWdEu4XT4PEKj3ZH MOjC3HZEIfa66RK1TBeEG/WCkKgtexSF+vwZsutv5r4LaOdJHeCh+hkN2lpaa/veVAbC 1QD+7hYjx16utCaIht00wH+xNoxmKhtvEm4VYw7bswh90sAVzAywGDeKFQ05NlYHgNnf FZRQ== X-Forwarded-Encrypted: i=1; AJvYcCW0M97h2iX9UNRXLRAl/AYH4oKVmWdgifNHZWXyU86q1kvlkzKnNTWBZdGoOckTRDRms1F+gbsU3Ww6B+VpF01HCved/3g= X-Gm-Message-State: AOJu0YxcEH7QFsUmOdrSaU/D/OMgEZkULvABlEBh57/GWgK4zGGIg7gT itZkkUF6gK1Epwwt58X8Mt7tFPiaGUTZtQ3HylcpmHJejWENVCXPPbyMb3tA5/o= X-Google-Smtp-Source: AGHT+IEPzBiyamH8HajiIAanCfaYKrF4d6zvsj2pCYaxgpaQcWPNs2s/mky4ykJihrWfUqWYewBaKQ== X-Received: by 2002:a05:620a:372a:b0:787:2d4a:e91 with SMTP id de42-20020a05620a372a00b007872d4a0e91mr9362184qkb.12.1708019229933; Thu, 15 Feb 2024 09:47:09 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-68-80-239.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.68.80.239]) by smtp.gmail.com with ESMTPSA id bj27-20020a05620a191b00b007873df5a625sm182249qkb.97.2024.02.15.09.47.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Feb 2024 09:47:09 -0800 (PST) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1rafpE-001DT3-Rz; Thu, 15 Feb 2024 13:47:08 -0400 Date: Thu, 15 Feb 2024 13:47:08 -0400 From: Jason Gunthorpe To: Lu Baolu Cc: Joerg Roedel , Will Deacon , Robin Murphy , Kevin Tian , Huang Jiaqing , Ethan Zhao , iommu@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] iommu/vt-d: Use rbtree to track iommu probed devices Message-ID: <20240215174708.GC1299735@ziepe.ca> References: <20240215072249.4465-1-baolu.lu@linux.intel.com> <20240215072249.4465-2-baolu.lu@linux.intel.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240215072249.4465-2-baolu.lu@linux.intel.com> On Thu, Feb 15, 2024 at 03:22:48PM +0800, Lu Baolu wrote: > Use a red-black tree(rbtree) to track devices probed by the driver's > probe_device callback. These devices need to be looked up quickly by > a source ID when the hardware reports a fault, either recoverable or > unrecoverable. > > Fault reporting paths are critical. Searching a list in this scenario > is inefficient, with an algorithm complexity of O(n). An rbtree is a > self-balancing binary search tree, offering an average search time > complexity of O(log(n)). This significant performance improvement > makes rbtrees a better choice. > > Furthermore, rbtrees are implemented on a per-iommu basis, eliminating > the need for global searches and further enhancing efficiency in > critical fault paths. The rbtree is protected by a spin lock with > interrupts disabled to ensure thread-safe access even within interrupt > contexts. > > Co-developed-by: Huang Jiaqing > Signed-off-by: Huang Jiaqing > Signed-off-by: Lu Baolu > --- > drivers/iommu/intel/iommu.h | 7 +++++ > drivers/iommu/intel/dmar.c | 3 +- > drivers/iommu/intel/iommu.c | 62 +++++++++++++++++++++++++++++++++++-- > 3 files changed, 69 insertions(+), 3 deletions(-) Reviewed-by: Jason Gunthorpe > +static int device_rbtree_insert(struct intel_iommu *iommu, > + struct device_domain_info *info) > +{ > + struct rb_node *curr; > + unsigned long flags; > + > + spin_lock_irqsave(&iommu->device_rbtree_lock, flags); > + curr = rb_find_add(&info->node, &iommu->device_rbtree, device_rid_cmp); > + spin_unlock_irqrestore(&iommu->device_rbtree_lock, flags); > + if (curr) > + dev_warn(info->dev, "device already in rbtree\n"); I would suggest WARN_ON(curr); Something has gone really wonky at this point, right? Jason