From: Dan Williams <dan.j.williams@xxxxxxxxx>
commit 08b9e0ab8af48895337192e683de44ab1e1b7427 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: 8fdcb1704f61 ("cxl/pmem: Add initial infrastructure for pmem support")
Cc: <stable@xxxxxxxxxxxxxxx>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Reviewed-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
Link: https://lore.kernel.org/r/163553734757.2509761.3305231863616785470.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/cxl/pmem.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
--- a/drivers/cxl/pmem.c
+++ b/drivers/cxl/pmem.c
@@ -149,14 +149,24 @@ static void cxl_nvb_update_state(struct
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(struc
}
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;
}
