From patchwork Sat Jun 3 02:09:24 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ira Weiny X-Patchwork-Id: 13265996 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) (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 54B561FAA for ; Sat, 3 Jun 2023 02:09:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1685758178; x=1717294178; h=from:date:subject:mime-version:content-transfer-encoding: message-id:references:in-reply-to:to:cc; bh=0hJMjkHkP89rfwhPu6kPTDLYbVJWhkUm9t7eLmXGvlc=; b=gTnsQsfrDhHK+u61fuRVfWkt7DSFABgpPsCiZbjOfuyrAT5uWfZXjUBs 57xEMK/UoDKjzT1M0pWR65IJwvYJzmwEX+5aSR46CbW64cdiNxZCDXz5u Ea0RZUw+kXC8mso7phyxEPRJ4sfJo89ztaUgM2E8kEodnJXua9+rkT9uG J6YAx/RZDyTRN7AWdjkt4yZlvOTbuQdPiun/XxE+9slL4ZujuV3DCg4UG 3ZJaeAEfDpV0NZatN6gZSRxpjdMTCrJxOMAcwdsPT6hMn31EB4Qxm0wUS KyLuD1U5nlB1tmDl1yhJXkOEs/43CZ5DJ723wychtKwWy5WlT7YsZzsmy w==; X-IronPort-AV: E=McAfee;i="6600,9927,10729"; a="340649459" X-IronPort-AV: E=Sophos;i="6.00,214,1681196400"; d="scan'208";a="340649459" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Jun 2023 19:09:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10729"; a="852354422" X-IronPort-AV: E=Sophos;i="6.00,214,1681196400"; d="scan'208";a="852354422" Received: from iweiny-mobl.amr.corp.intel.com (HELO localhost) ([10.212.97.230]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Jun 2023 19:09:36 -0700 From: Ira Weiny Date: Fri, 02 Jun 2023 19:09:24 -0700 Subject: [PATCH RFC 4/4] dax/bus: Remove unnecessary reference in alloc_dax_region() Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20230602-dax-region-put-v1-4-d8668f335d45@intel.com> References: <20230602-dax-region-put-v1-0-d8668f335d45@intel.com> In-Reply-To: <20230602-dax-region-put-v1-0-d8668f335d45@intel.com> To: Dan Williams , Vishal Verma , Dave Jiang , Andrew Morton , Joao Martins , Jonathan Cameron Cc: Yongqiang Liu , Paul Cassella , linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, Ira Weiny X-Mailer: b4 0.13-dev-9a8cd X-Developer-Signature: v=1; a=ed25519-sha256; t=1685758165; l=3727; i=ira.weiny@intel.com; s=20221211; h=from:subject:message-id; bh=0hJMjkHkP89rfwhPu6kPTDLYbVJWhkUm9t7eLmXGvlc=; b=h+bWgJ3qSIdj/EAGT1xs+38BAs20p/pFFmvnjS5xGpX1ZfEYrwqiL/b98IYQKtcO0Pyp94reN TH2URAb3gZBAYVKG0d2P5cvNhWCAN5Z7GnIaqBSgYazRlbKWajzaBFp X-Developer-Key: i=ira.weiny@intel.com; a=ed25519; pk=noldbkG+Wp1qXRrrkfY1QJpDf7QsOEthbOT7vm0PqsE= All the callers to alloc_dax_region() maintain the device associated with the dax_region until the dax_region is referenced by the dax_dev they are creating. Remove the extra kref that alloc_dax_region() takes. Add a comment to clarify the reference counting should additional callers be grown later. Cc: Yongqiang Liu Cc: Dan Williams Cc: Paul Cassella Signed-off-by: Ira Weiny --- drivers/dax/bus.c | 13 ++++++------- drivers/dax/cxl.c | 4 ---- drivers/dax/hmem/hmem.c | 3 --- drivers/dax/pmem.c | 8 +------- 4 files changed, 7 insertions(+), 21 deletions(-) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 899e29d107b4..ed34d8aa6b26 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -583,7 +583,11 @@ static void dax_region_unregister(void *region) dax_region_put(dax_region); } -/* The dax_region reference returned should be dropped with dax_region_put() */ +/* + * Caller is responsible to ensure the parent device stays live while the + * returned dax_region is in use. Or as is typically the case, a separate + * reference should be taken. + */ struct dax_region *alloc_dax_region(struct device *parent, int region_id, struct range *range, int target_node, unsigned int align, unsigned long flags) @@ -626,13 +630,8 @@ struct dax_region *alloc_dax_region(struct device *parent, int region_id, return NULL; } - /* Hold a reference to return to the caller */ - kref_get(&dax_region->kref); - if (devm_add_action_or_reset(parent, dax_region_unregister, - dax_region)) { - kref_put(&dax_region->kref, dax_region_free); + if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region)) return NULL; - } return dax_region; } EXPORT_SYMBOL_GPL(alloc_dax_region); diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c index bbfe71cf4325..5ad600ee68b3 100644 --- a/drivers/dax/cxl.c +++ b/drivers/dax/cxl.c @@ -29,10 +29,6 @@ static int cxl_dax_region_probe(struct device *dev) .size = range_len(&cxlr_dax->hpa_range), }; dev_dax = devm_create_dev_dax(&data); - - /* child dev_dax instances now own the lifetime of the dax_region */ - dax_region_put(dax_region); - return IS_ERR(dev_dax) ? PTR_ERR(dev_dax) : 0; } diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c index b4831a3d3934..46e1b343f26e 100644 --- a/drivers/dax/hmem/hmem.c +++ b/drivers/dax/hmem/hmem.c @@ -39,9 +39,6 @@ static int dax_hmem_probe(struct platform_device *pdev) .size = region_idle ? 0 : range_len(&mri->range), }; dev_dax = devm_create_dev_dax(&data); - - /* child dev_dax instances now own the lifetime of the dax_region */ - dax_region_put(dax_region); return IS_ERR(dev_dax) ? PTR_ERR(dev_dax) : 0; } diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c index f050ea78bb83..a4f016d7f4f5 100644 --- a/drivers/dax/pmem.c +++ b/drivers/dax/pmem.c @@ -13,7 +13,6 @@ static struct dev_dax *__dax_pmem_probe(struct device *dev) int rc, id, region_id; resource_size_t offset; struct nd_pfn_sb *pfn_sb; - struct dev_dax *dev_dax; struct dev_dax_data data; struct nd_namespace_io *nsio; struct dax_region *dax_region; @@ -65,12 +64,7 @@ static struct dev_dax *__dax_pmem_probe(struct device *dev) .pgmap = &pgmap, .size = range_len(&range), }; - dev_dax = devm_create_dev_dax(&data); - - /* child dev_dax instances now own the lifetime of the dax_region */ - dax_region_put(dax_region); - - return dev_dax; + return devm_create_dev_dax(&data); } static int dax_pmem_probe(struct device *dev)