Commit 08b9e0ab authored by Dan Williams's avatar Dan Williams
Browse files

cxl/pmem: Fix reference counting for delayed work 



There is a potential race between queue_work() returning and the
queued-work running that could result in put_device() running before
get_device(). Introduce the cxl_nvdimm_bridge_state_work() helper that
takes the reference unconditionally, but drops it if no new work was
queued, to keep the references balanced.

Fixes: 8fdcb170 ("cxl/pmem: Add initial infrastructure for pmem support")
Cc: <stable@vger.kernel.org>
Reviewed-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: default avatarBen Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/163553734757.2509761.3305231863616785470.stgit@dwillia2-desk3.amr.corp.intel.com


Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent fa55b7dc

drivers/cxl/pmem.c

+13 −4
Original line number Diff line number Diff line
@@ -266,14 +266,24 @@ static void cxl_nvb_update_state(struct work_struct *work) 
	put_device(&cxl_nvb->dev);

}



static void cxl_nvdimm_bridge_state_work(struct cxl_nvdimm_bridge *cxl_nvb)

{

	/*

	 * Take a reference that the workqueue will drop if new work

	 * gets queued.

	 */

	get_device(&cxl_nvb->dev);

	if (!queue_work(cxl_pmem_wq, &cxl_nvb->state_work))

		put_device(&cxl_nvb->dev);

}



static void cxl_nvdimm_bridge_remove(struct device *dev)

{

	struct cxl_nvdimm_bridge *cxl_nvb = to_cxl_nvdimm_bridge(dev);



	if (cxl_nvb->state == CXL_NVB_ONLINE)

		cxl_nvb->state = CXL_NVB_OFFLINE;

	if (queue_work(cxl_pmem_wq, &cxl_nvb->state_work))

		get_device(&cxl_nvb->dev);

	cxl_nvdimm_bridge_state_work(cxl_nvb);

}



static int cxl_nvdimm_bridge_probe(struct device *dev)
@@ -294,8 +304,7 @@ static int cxl_nvdimm_bridge_probe(struct device *dev) 
	}



	cxl_nvb->state = CXL_NVB_ONLINE;

	if (queue_work(cxl_pmem_wq, &cxl_nvb->state_work))

		get_device(&cxl_nvb->dev);

	cxl_nvdimm_bridge_state_work(cxl_nvb);



	return 0;

}