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authorDan Williams <dan.j.williams@intel.com>2023-01-20 16:26:12 -0800
committerDan Williams <dan.j.williams@intel.com>2023-01-25 15:35:26 -0800
commit19398821b25a9cde564265262e680ae1c2351be7 (patch)
tree16cfd9c33194f8e926af7c806677940cf16b09f8 /drivers/cxl/pmem.c
parent2ec1b17f745b08526220f3c169d2eb9799a9be39 (diff)
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.c24
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);
}