From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 12AA43BB130 for ; Tue, 19 May 2026 21:02:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779224525; cv=none; b=rKyjnt8bRczSyGWuWLIeXKssJpfe3WcpihGuPwj6HSqdEkgnhwdtBOBVvjMhfaZ7l2uruCNNizU6rIthoUf6xmq+YakIkdPiuYzERnzk7S5YT3UqCwNoHaQPcLu/q0sgmlpOYwC32LLloEFPa8Vy5I7tKFzkDTPFVKmNUmh3CgY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779224525; c=relaxed/simple; bh=T16Ngfqy8AC1yMgKRQ/g7jrOk4JNdAG0x9oBzEhayM0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=riurCv0EA3rr4GkbZPapJKzB7APoFgZmen1DENHuAEXPhKdVZfwN00veSBj/EcScJPnqi1dHpEKf20DB4HQltLDOHzIztHdT3cjF7K39str8lJu5PWnOHYMFEGqKUN0WBgjc7CGiyVM5nB6nSX4mKYpdLYrH/f8NNySxdcJjupk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZGVuCubf; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZGVuCubf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8DF9A1F00894; Tue, 19 May 2026 21:02:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779224523; bh=p03xqoQYlYArBvp2NbGkqXi3xPKw+zRyIno6T8ri+L0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ZGVuCubf8orBnh0tg06Bp+A+cwj+odlap2VcwDTOdO7yXOe7VLvcr5BWx5LIPvs/+ 6InLoRcj8U+mG+OgV5x4SsDweZXAHf0sui3BVH5EM0Pw5Z3zGhdsE5SiGX4jtKrxWF HzJH8mwn6ocXIBCtDYG35I2JsH0WDB2CzJUx2RKaNjSW3y3YZVPh1rAL9ZjAEinEoT em8A5+X+MZnZksJU8vuDcP37JQnol7wDaM8/vcwtdLeV9zKOtC93xGO9rIm+0o9sU2 jwS5/OgmqTJWMS60+omEtxHpTanAFf7pxVkrvd33tpWM/buTKxPfUok4SH7coGv3fH m86n7/MfWi/Qg== Received: from phl-compute-06.internal (phl-compute-06.internal [10.202.2.46]) by mailfauth.phl.internal (Postfix) with ESMTP id EC862F40075; Tue, 19 May 2026 17:02:02 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-06.internal (MEProxy); Tue, 19 May 2026 17:02:02 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefhedrtddtgddugedvjeekucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucenucfjughrpefhvfevufffkffojghfggfgsedtkeertd ertddtnecuhfhrohhmpeffrghnucghihhllhhirghmshcuoegujhgsfieskhgvrhhnvghl rdhorhhgqeenucggtffrrghtthgvrhhnpeeuheffhfelleelgedutdfhleefjeejvedtke fgjeefgfettdeljeefvefhueeiveenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgr mhepmhgrihhlfhhrohhmpegujhgsfidomhgvshhmthhprghuthhhphgvrhhsohhnrghlih hthidqudejjedvfedtgeehhedqfeeffeelgedtgeejqdgujhgsfieppehkvghrnhgvlhdr ohhrghesfhgrshhtmhgrihhlrdgtohhmpdhnsggprhgtphhtthhopeehpdhmohguvgepsh hmthhpohhuthdprhgtphhtthhopehlihhnuhigqdgtgihlsehvghgvrhdrkhgvrhhnvghl rdhorhhgpdhrtghpthhtohepuggrvhgvrdhjihgrnhhgsehinhhtvghlrdgtohhmpdhrtg hpthhtoheprghlvghjrghnughrohdrlhhutggvrhhoqdhprghlrghusegrmhgurdgtohhm pdhrtghpthhtohepjhhitgdvfeeskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepughjsg ifsehkvghrnhgvlhdrohhrgh X-ME-Proxy: Feedback-ID: i67ae4b3e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 19 May 2026 17:02:02 -0400 (EDT) From: Dan Williams To: linux-cxl@vger.kernel.org Cc: dave.jiang@intel.com, alejandro.lucero-palau@amd.com, jic23@kernel.org Subject: [PATCH 1/5] cxl/region: Block region delete during region creation Date: Tue, 19 May 2026 14:01:54 -0700 Message-ID: <20260519210158.1499795-2-djbw@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260519210158.1499795-1-djbw@kernel.org> References: <20260519210158.1499795-1-djbw@kernel.org> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Expand the range lock, rename it "regions_lock", to disable region deletion in the critical period between construct_region() and attach_target(), as well as the period between device_add() and registering the remove actions. Otherwise, userspace can confuse the kernel. It can violate the assumption the region stays registered through the completion of cxl_add_to_region(). It can violate the assumption that devm_add_action_or_reset() is working with a live 'struct cxl_region'. It is ok for the region to disappear outside of those windows as that mirrors device hotplug flows where the proper locks are held. Fixes: a32320b71f08 ("cxl/region: Add region autodiscovery") Signed-off-by: Dan Williams --- drivers/cxl/cxl.h | 4 ++-- drivers/cxl/core/port.c | 2 +- drivers/cxl/core/region.c | 12 ++++++++++-- 3 files changed, 13 insertions(+), 5 deletions(-) diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index 1297594beaec..3900a0778571 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -359,7 +359,7 @@ struct cxl_rd_ops { * @cache_size: extended linear cache size if exists, otherwise zero. * @region_id: region id for next region provisioning event * @platform_data: platform specific configuration data - * @range_lock: sync region autodiscovery by address range + * @regions_lock: sync region discovery, construction, and deletion * @qos_class: QoS performance class cookie * @ops: CXL root decoder operations * @cxlsd: base cxl switch decoder @@ -369,7 +369,7 @@ struct cxl_root_decoder { resource_size_t cache_size; atomic_t region_id; void *platform_data; - struct mutex range_lock; + struct mutex regions_lock; int qos_class; struct cxl_rd_ops ops; struct cxl_switch_decoder cxlsd; diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index c5aacd7054f1..6e7a70d51cfe 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -2016,7 +2016,7 @@ struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port, return ERR_PTR(rc); } - mutex_init(&cxlrd->range_lock); + mutex_init(&cxlrd->regions_lock); cxld = &cxlsd->cxld; cxld->dev.type = &cxl_decoder_root_type; diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index e50dc716d4e8..b5601e89e302 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -2779,6 +2779,10 @@ static ssize_t create_region_store(struct device *dev, const char *buf, if (rc != 1) return -EINVAL; + ACQUIRE(mutex_intr, regions_lock)(&cxlrd->regions_lock); + if ((rc = ACQUIRE_ERR(mutex_intr, ®ions_lock))) + return rc; + cxlr = __create_region(cxlrd, mode, id, CXL_DECODER_HOSTONLYMEM); if (IS_ERR(cxlr)) return PTR_ERR(cxlr); @@ -2838,6 +2842,11 @@ static ssize_t delete_region_store(struct device *dev, struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev); struct cxl_port *port = to_cxl_port(dev->parent); struct cxl_region *cxlr; + int rc; + + ACQUIRE(mutex_intr, regions_lock)(&cxlrd->regions_lock); + if ((rc = ACQUIRE_ERR(mutex_intr, ®ions_lock))) + return rc; cxlr = cxl_find_region_by_name(cxlrd, buf); if (IS_ERR(cxlr)) @@ -3776,12 +3785,11 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled) * for the HPA range, one does the construction and the others * add to that. */ - mutex_lock(&cxlrd->range_lock); + guard(mutex)(&cxlrd->regions_lock); struct cxl_region *cxlr __free(put_cxl_region) = cxl_find_region_by_range(cxlrd, &ctx.hpa_range); if (!cxlr) cxlr = construct_region(cxlrd, &ctx); - mutex_unlock(&cxlrd->range_lock); rc = PTR_ERR_OR_ZERO(cxlr); if (rc) -- 2.53.0