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cxl/pmem: Fix reference counting for delayed work 

commit 08b9e0ab8a upstream.

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: 8fdcb1704f ("cxl/pmem: Add initial infrastructure for pmem support")
Cc: <stable@vger.kernel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/163553734757.2509761.3305231863616785470.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dan Williams 2021-10-29 12:55:47 -07:00 committed by Greg Kroah-Hartman
parent bc95dbf550
commit 181c78d6c1
1 changed files with 13 additions and 4 deletions
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17
drivers/cxl/pmem.c
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@ -149,14 +149,24 @@ 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)
@ -177,8 +187,7 @@ 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;
}