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From: Dan Williams <dan.j.williams@intel.com>
To: linux-cxl@vger.kernel.org
Cc: Jason Gunthorpe <jgg@nvidia.com>,
	ira.weiny@intel.com, vishal.l.verma@intel.com,
	alison.schofield@intel.com, linux-kernel@vger.kernel.org
Subject: [PATCH 2/4] cxl/mem: Fix cdev_device_add() error handling
Date: Wed, 24 Mar 2021 14:01:56 -0700	[thread overview]
Message-ID: <161661971651.1721612.7457823773061754064.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
In-Reply-To: <161661970558.1721612.10441826898835759137.stgit@dwillia2-desk3.amr.corp.intel.com>

If cdev_device_add() fails then the allocation performed by
dev_set_name() is leaked. Use put_device(), not open coded release, for
device_add() failures.

The comment is obsolete because direct err_id failures need not worry
about the device being live.

The release method expects the percpu_ref is already dead, so
percpu_ref_kill() is needed before put_device(). However, given that the
cdev was partially live wait_for_completion() also belongs in the
release method.

Fixes: b39cb1052a5c ("cxl/mem: Register CXL memX devices")
Reported-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/mem.c |   16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 30bf4f0f3c17..e53d573ae4ab 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -1049,6 +1049,7 @@ static void cxl_memdev_release(struct device *dev)
 {
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
 
+	wait_for_completion(&cxlmd->ops_dead);
 	percpu_ref_exit(&cxlmd->ops_active);
 	ida_free(&cxl_memdev_ida, cxlmd->id);
 	kfree(cxlmd);
@@ -1157,7 +1158,6 @@ static void cxlmdev_unregister(void *_cxlmd)
 
 	percpu_ref_kill(&cxlmd->ops_active);
 	cdev_device_del(&cxlmd->cdev, dev);
-	wait_for_completion(&cxlmd->ops_dead);
 	cxlmd->cxlm = NULL;
 	put_device(dev);
 }
@@ -1210,20 +1210,16 @@ static int cxl_mem_add_memdev(struct cxl_mem *cxlm)
 	cdev_init(cdev, &cxl_memdev_fops);
 
 	rc = cdev_device_add(cdev, dev);
-	if (rc)
-		goto err_add;
+	if (rc) {
+		percpu_ref_kill(&cxlmd->ops_active);
+		put_device(dev);
+		return rc;
+	}
 
 	return devm_add_action_or_reset(dev->parent, cxlmdev_unregister, cxlmd);
 
-err_add:
-	ida_free(&cxl_memdev_ida, cxlmd->id);
 err_id:
-	/*
-	 * Theoretically userspace could have already entered the fops,
-	 * so flush ops_active.
-	 */
 	percpu_ref_kill(&cxlmd->ops_active);
-	wait_for_completion(&cxlmd->ops_dead);
 	percpu_ref_exit(&cxlmd->ops_active);
 err_ref:
 	kfree(cxlmd);


  parent reply	other threads:[~2021-03-24 21:02 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-24 21:01 [PATCH 0/4] cxl/mem: Fix memdev device setup Dan Williams
2021-03-24 21:01 ` [PATCH 1/4] cxl/mem: Use sysfs_emit() for attribute show routines Dan Williams
2021-03-25 16:49   ` Jason Gunthorpe
2021-03-24 21:01 ` Dan Williams [this message]
2021-03-25 17:11   ` [PATCH 2/4] cxl/mem: Fix cdev_device_add() error handling Jason Gunthorpe
2021-03-29 21:03     ` Dan Williams
2021-03-29 22:44       ` Jason Gunthorpe
2021-03-30  4:48         ` Dan Williams
2021-03-24 21:02 ` [PATCH 3/4] cxl/mem: Do not rely on device_add() side effects for dev_set_name() failures Dan Williams
2021-03-25 17:14   ` Jason Gunthorpe
2021-03-24 21:02 ` [PATCH 4/4] cxl/mem: Disable cxl device power management Dan Williams

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