From patchwork Tue Apr 30 17:44:24 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Verma, Vishal L" X-Patchwork-Id: 13649814 X-Patchwork-Delegate: patchwork-bot@kernel.org Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.10]) (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 61D79180A69 for ; Tue, 30 Apr 2024 17:44:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.10 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714499084; cv=none; b=Dzfcqrl5IjOUmdNtfus+ROeMeCzjjgVDPl7extFFyW99btbN+bZ7K2uoQo61GYZRv7pw0vEeuvMrT1/V77yQrUUdtDlYAFF2BR15iTC/afb7yCalnAkEugf0+C8xfZ5PJ7a2Y+fI3sTEbVYNFpk7yyu8g7pYzsyfd5oVBmtGNpk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714499084; c=relaxed/simple; bh=T52oU7nq5CORc4zUmW3MiR7iyOzbCEAUapTKwbnnDtE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=DAC78Gaqp6Kl6dyAjoHmYzay+lJdjp8K2UyZnCg7TQiQg06n1YajK21Zm2kHCUJVLmefRG2dJMGL0J4FYjetdXFjoK3IaqYCnheKXKxHH+c4Rju0e8P6g1xIR2L30o1a4b/KJzOi1KX7qFHTQN6nw2w57G/pZSeGY2w58/OLigI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=UhAKU//5; arc=none smtp.client-ip=198.175.65.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="UhAKU//5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1714499083; x=1746035083; h=from:date:subject:mime-version:content-transfer-encoding: message-id:references:in-reply-to:to:cc; bh=T52oU7nq5CORc4zUmW3MiR7iyOzbCEAUapTKwbnnDtE=; b=UhAKU//5mcOT/+qEbytkyG8n9ORoIFLzDxbWeZkSAgFx+SdITijffnBe J5mEapMrD+3l9Sfoc0GLzRv+1jZrPprzpxi0GQPUxnv3eHzgRUCX5TbWe qNRMWYwveR32vRi+hVucwBQ3vRaxZwr+3VMW/SDQowRFcurMtv5vwHB37 AFBdX8GThFOjI50O8OFFADSvUDht6R890C8CM1olyNMmDW/RPjMKYQGp6 d9sAswxV3a95asNT9koMJSi18JGI6uGPFIhkGnO+5yhsPv0kTikj7CAIi EQNJIvS/3oo/rjsPZ2Q5s44qhWFP2FSr3awPWO9ofVttmO0+HclyFAoqI Q==; X-CSE-ConnectionGUID: js3NtGyZT521ir97AO9+7Q== X-CSE-MsgGUID: NrlJS+JtRAqGQwBMvHlB+A== X-IronPort-AV: E=McAfee;i="6600,9927,11060"; a="27669834" X-IronPort-AV: E=Sophos;i="6.07,242,1708416000"; d="scan'208";a="27669834" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Apr 2024 10:44:41 -0700 X-CSE-ConnectionGUID: mAtDHbLVRkeXR30fmCFHxg== X-CSE-MsgGUID: liAd+UmlS8+j6gqf+bh/lw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,242,1708416000"; d="scan'208";a="26534777" Received: from vverma7-desk1.amr.corp.intel.com (HELO [192.168.1.200]) ([10.212.82.45]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Apr 2024 10:44:41 -0700 From: Vishal Verma Date: Tue, 30 Apr 2024 11:44:24 -0600 Subject: [PATCH v3 2/4] dax/bus.c: fix locking for unregister_dax_dev / unregister_dax_mapping paths Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240430-vv-dax_abi_fixes-v3-2-e3dcd755774c@intel.com> References: <20240430-vv-dax_abi_fixes-v3-0-e3dcd755774c@intel.com> In-Reply-To: <20240430-vv-dax_abi_fixes-v3-0-e3dcd755774c@intel.com> To: Dan Williams , Dave Jiang , Alison Schofield , Andrew Morton Cc: linux-mm@kvack.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org, Vishal Verma X-Mailer: b4 0.14-dev-5ce50 X-Developer-Signature: v=1; a=openpgp-sha256; l=3760; i=vishal.l.verma@intel.com; h=from:subject:message-id; bh=T52oU7nq5CORc4zUmW3MiR7iyOzbCEAUapTKwbnnDtE=; b=owGbwMvMwCXGf25diOft7jLG02pJDGmGehxf90/d0nXems10qoBf6nS+bxeNLjG1dP1Rc0w4I ZLQVyrYUcrCIMbFICumyPJ3z0fGY3Lb83kCExxh5rAygQxh4OIUgIlozmFkOLHqhbMVN3/OfKaM yUJ3l3GLbshgnx3VKqeklKO6MZqFi+GfUd+7g/M8FsVor3m469bJ2YYu7+06zvy3FJl/6Ln69rP X+QE= X-Developer-Key: i=vishal.l.verma@intel.com; a=openpgp; fpr=F8682BE134C67A12332A2ED07AFA61BEA3B84DFF Commit c05ae9d85b47 ("dax/bus.c: replace driver-core lock usage by a local rwsem") aimed to undo device_lock() abuses for protecting changes to dax-driver internal data-structures like the dax_region resource tree to device-dax-instance range structures. However, the device_lock() was legitamately enforcing that devices to be deleted were not current actively attached to any driver nor assigned any capacity from the region. As a result of the device_lock restoration in delete_store(), the conditional locking in unregister_dev_dax() and unregister_dax_mapping() can be removed. Fixes: c05ae9d85b47 ("dax/bus.c: replace driver-core lock usage by a local rwsem") Reported-by: Dan Williams Reviewed-by: Dan Williams Signed-off-by: Vishal Verma --- drivers/dax/bus.c | 42 ++++++++---------------------------------- 1 file changed, 8 insertions(+), 34 deletions(-) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 7924dd542a13..e2c7354ce328 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -465,26 +465,17 @@ static void free_dev_dax_ranges(struct dev_dax *dev_dax) trim_dev_dax_range(dev_dax); } -static void __unregister_dev_dax(void *dev) +static void unregister_dev_dax(void *dev) { struct dev_dax *dev_dax = to_dev_dax(dev); dev_dbg(dev, "%s\n", __func__); + down_write(&dax_region_rwsem); kill_dev_dax(dev_dax); device_del(dev); free_dev_dax_ranges(dev_dax); put_device(dev); -} - -static void unregister_dev_dax(void *dev) -{ - if (rwsem_is_locked(&dax_region_rwsem)) - return __unregister_dev_dax(dev); - - if (WARN_ON_ONCE(down_write_killable(&dax_region_rwsem) != 0)) - return; - __unregister_dev_dax(dev); up_write(&dax_region_rwsem); } @@ -560,15 +551,10 @@ static ssize_t delete_store(struct device *dev, struct device_attribute *attr, if (!victim) return -ENXIO; - rc = down_write_killable(&dax_region_rwsem); - if (rc) - return rc; - rc = down_write_killable(&dax_dev_rwsem); - if (rc) { - up_write(&dax_region_rwsem); - return rc; - } + device_lock(dev); + device_lock(victim); dev_dax = to_dev_dax(victim); + down_write(&dax_dev_rwsem); if (victim->driver || dev_dax_size(dev_dax)) rc = -EBUSY; else { @@ -589,11 +575,12 @@ static ssize_t delete_store(struct device *dev, struct device_attribute *attr, rc = -EBUSY; } up_write(&dax_dev_rwsem); + device_unlock(victim); /* won the race to invalidate the device, clean it up */ if (do_del) devm_release_action(dev, unregister_dev_dax, victim); - up_write(&dax_region_rwsem); + device_unlock(dev); put_device(victim); return rc; @@ -705,7 +692,7 @@ static void dax_mapping_release(struct device *dev) put_device(parent); } -static void __unregister_dax_mapping(void *data) +static void unregister_dax_mapping(void *data) { struct device *dev = data; struct dax_mapping *mapping = to_dax_mapping(dev); @@ -713,25 +700,12 @@ static void __unregister_dax_mapping(void *data) dev_dbg(dev, "%s\n", __func__); - lockdep_assert_held_write(&dax_region_rwsem); - dev_dax->ranges[mapping->range_id].mapping = NULL; mapping->range_id = -1; device_unregister(dev); } -static void unregister_dax_mapping(void *data) -{ - if (rwsem_is_locked(&dax_region_rwsem)) - return __unregister_dax_mapping(data); - - if (WARN_ON_ONCE(down_write_killable(&dax_region_rwsem) != 0)) - return; - __unregister_dax_mapping(data); - up_write(&dax_region_rwsem); -} - static struct dev_dax_range *get_dax_range(struct device *dev) { struct dax_mapping *mapping = to_dax_mapping(dev);