From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 5FE5621BADAB2 for ; Tue, 31 Jul 2018 07:32:50 -0700 (PDT) From: Stefan Hajnoczi Subject: [PATCH] device-dax: avoid hang on error before devm_memremap_pages() Date: Tue, 31 Jul 2018 15:32:46 +0100 Message-Id: <20180731143246.16915-1-stefanha@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: linux-nvdimm@lists.01.org Cc: linux-kernel@vger.kernel.org, Stefan Hajnoczi List-ID: dax_pmem_percpu_exit() waits for dax_pmem_percpu_release() to invoke the dax_pmem->cmp completion. Unfortunately this approach to cleaning up the percpu_ref only works after devm_memremap_pages() was successful. If devm_add_action_or_reset() or devm_memremap_pages() fails, dax_pmem_percpu_release() is not invoked. Therefore dax_pmem_percpu_exit() hangs waiting for the completion: rc = devm_add_action_or_reset(dev, dax_pmem_percpu_exit, &dax_pmem->ref); if (rc) return rc; dax_pmem->pgmap.ref = &dax_pmem->ref; addr = devm_memremap_pages(dev, &dax_pmem->pgmap); Avoid the hang by calling percpu_ref_exit() in the error paths instead of going through dax_pmem_percpu_exit(). Signed-off-by: Stefan Hajnoczi --- Found by code inspection. Compile-tested only. --- drivers/dax/pmem.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c index fd49b24fd6af..99e2aace8078 100644 --- a/drivers/dax/pmem.c +++ b/drivers/dax/pmem.c @@ -105,15 +105,19 @@ static int dax_pmem_probe(struct device *dev) if (rc) return rc; - rc = devm_add_action_or_reset(dev, dax_pmem_percpu_exit, - &dax_pmem->ref); - if (rc) + rc = devm_add_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref); + if (rc) { + percpu_ref_exit(&dax_pmem->ref); return rc; + } dax_pmem->pgmap.ref = &dax_pmem->ref; addr = devm_memremap_pages(dev, &dax_pmem->pgmap); - if (IS_ERR(addr)) + if (IS_ERR(addr)) { + devm_remove_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref); + percpu_ref_exit(&dax_pmem->ref); return PTR_ERR(addr); + } rc = devm_add_action_or_reset(dev, dax_pmem_percpu_kill, &dax_pmem->ref); -- 2.17.1 _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm