diff options
author | Dan Williams <dan.j.williams@intel.com> | 2023-01-20 16:26:12 -0800 |
---|---|---|
committer | Dan Williams <dan.j.williams@intel.com> | 2023-01-25 15:35:26 -0800 |
commit | 19398821b25a9cde564265262e680ae1c2351be7 (patch) | |
tree | 16cfd9c33194f8e926af7c806677940cf16b09f8 /drivers/cxl/core/pmem.c | |
parent | 2ec1b17f745b08526220f3c169d2eb9799a9be39 (diff) | |
download | linux-19398821b25a9cde564265262e680ae1c2351be7.tar.bz2 |
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/core/pmem.c')
-rw-r--r-- | drivers/cxl/core/pmem.c | 42 |
1 files changed, 4 insertions, 38 deletions
diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c index f3d2169b6731..c2e4b1093788 100644 --- a/drivers/cxl/core/pmem.c +++ b/drivers/cxl/core/pmem.c @@ -227,34 +227,16 @@ static struct cxl_nvdimm *cxl_nvdimm_alloc(struct cxl_nvdimm_bridge *cxl_nvb, return cxl_nvd; } -static void cxl_nvd_unregister(void *_cxl_nvd) +static void cxlmd_release_nvdimm(void *_cxlmd) { - struct cxl_nvdimm *cxl_nvd = _cxl_nvd; - struct cxl_memdev *cxlmd = cxl_nvd->cxlmd; + struct cxl_memdev *cxlmd = _cxlmd; + struct cxl_nvdimm *cxl_nvd = cxlmd->cxl_nvd; struct cxl_nvdimm_bridge *cxl_nvb = cxlmd->cxl_nvb; - /* - * Either the bridge is in ->remove() context under the device_lock(), - * or cxlmd_release_nvdimm() is cancelling the bridge's release action - * for @cxl_nvd and doing it itself (while manually holding the bridge - * lock). - */ - device_lock_assert(&cxl_nvb->dev); cxl_nvd->cxlmd = NULL; cxlmd->cxl_nvd = NULL; + cxlmd->cxl_nvb = NULL; device_unregister(&cxl_nvd->dev); -} - -static void cxlmd_release_nvdimm(void *_cxlmd) -{ - struct cxl_memdev *cxlmd = _cxlmd; - struct cxl_nvdimm_bridge *cxl_nvb = cxlmd->cxl_nvb; - - device_lock(&cxl_nvb->dev); - if (cxlmd->cxl_nvd) - devm_release_action(&cxl_nvb->dev, cxl_nvd_unregister, - cxlmd->cxl_nvd); - device_unlock(&cxl_nvb->dev); put_device(&cxl_nvb->dev); } @@ -293,22 +275,6 @@ int devm_cxl_add_nvdimm(struct cxl_memdev *cxlmd) dev_dbg(&cxlmd->dev, "register %s\n", dev_name(dev)); - /* - * The two actions below arrange for @cxl_nvd to be deleted when either - * the top-level PMEM bridge goes down, or the endpoint device goes - * through ->remove(). - */ - device_lock(&cxl_nvb->dev); - if (cxl_nvb->dev.driver) - rc = devm_add_action_or_reset(&cxl_nvb->dev, cxl_nvd_unregister, - cxl_nvd); - else - rc = -ENXIO; - device_unlock(&cxl_nvb->dev); - - if (rc) - goto err_alloc; - /* @cxlmd carries a reference on @cxl_nvb until cxlmd_release_nvdimm */ return devm_add_action_or_reset(&cxlmd->dev, cxlmd_release_nvdimm, cxlmd); |