diff options
author | Dan Williams <dan.j.williams@intel.com> | 2023-01-21 03:26:12 +0300 |
---|---|---|
committer | Dan Williams <dan.j.williams@intel.com> | 2023-01-26 02:35:26 +0300 |
commit | 19398821b25a9cde564265262e680ae1c2351be7 (patch) | |
tree | 16cfd9c33194f8e926af7c806677940cf16b09f8 /drivers/cxl/pmem.c | |
parent | 2ec1b17f745b08526220f3c169d2eb9799a9be39 (diff) | |
download | linux-19398821b25a9cde564265262e680ae1c2351be7.tar.xz |
cxl/pmem: Fix nvdimm unregistration when cxl_pmem driver is absent
The cxl_pmem.ko module houses the driver for both cxl_nvdimm_bridge
objects and cxl_nvdimm objects. When the core creates a cxl_nvdimm it
arranges for it to be autoremoved when the bridge goes down. However, if
the bridge never initialized because the cxl_pmem.ko module never
loaded, it sets up a the following crash scenario:
BUG: kernel NULL pointer dereference, address: 0000000000000478
[..]
RIP: 0010:cxl_nvdimm_probe+0x99/0x140 [cxl_pmem]
[..]
Call Trace:
<TASK>
cxl_bus_probe+0x17/0x50 [cxl_core]
really_probe+0xde/0x380
__driver_probe_device+0x78/0x170
driver_probe_device+0x1f/0x90
__driver_attach+0xd2/0x1c0
bus_for_each_dev+0x79/0xc0
bus_add_driver+0x1b1/0x200
driver_register+0x89/0xe0
cxl_pmem_init+0x50/0xff0 [cxl_pmem]
It turns out the recent rework to simplify nvdimm probing obviated the
need to unregister cxl_nvdimm objects at cxl_nvdimm_bridge ->remove()
time. Leave the cxl_nvdimm device registered until the hosting
cxl_memdev departs. The alternative is that the cxl_memdev needs to be
reattached whenever the cxl_nvdimm_bridge attach state cycles, which is
awkward and unnecessary.
The only requirement is to make sure that when the cxl_nvdimm_bridge
goes away any dependent cxl_nvdimm objects are shutdown. Handle that in
unregister_nvdimm_bus().
With these registration entanglements removed there is no longer a need
to pre-load the cxl_pmem module in cxl_acpi.
Fixes: cb9cfff82f6a ("cxl/acpi: Simplify cxl_nvdimm_bridge probing")
Reported-by: Gregory Price <gregory.price@memverge.com>
Debugged-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/167426077263.3955046.9695309346988027311.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/cxl/pmem.c')
-rw-r--r-- | drivers/cxl/pmem.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c index eedefebc4283..08bbbac9a6d0 100644 --- a/drivers/cxl/pmem.c +++ b/drivers/cxl/pmem.c @@ -225,11 +225,35 @@ static int cxl_pmem_ctl(struct nvdimm_bus_descriptor *nd_desc, return cxl_pmem_nvdimm_ctl(nvdimm, cmd, buf, buf_len); } +static int detach_nvdimm(struct device *dev, void *data) +{ + struct cxl_nvdimm *cxl_nvd; + bool release = false; + + if (!is_cxl_nvdimm(dev)) + return 0; + + device_lock(dev); + if (!dev->driver) + goto out; + + cxl_nvd = to_cxl_nvdimm(dev); + if (cxl_nvd->cxlmd && cxl_nvd->cxlmd->cxl_nvb == data) + release = true; +out: + device_unlock(dev); + if (release) + device_release_driver(dev); + return 0; +} + static void unregister_nvdimm_bus(void *_cxl_nvb) { struct cxl_nvdimm_bridge *cxl_nvb = _cxl_nvb; struct nvdimm_bus *nvdimm_bus = cxl_nvb->nvdimm_bus; + bus_for_each_dev(&cxl_bus_type, NULL, cxl_nvb, detach_nvdimm); + cxl_nvb->nvdimm_bus = NULL; nvdimm_bus_unregister(nvdimm_bus); } |