[PATCH 1/2] cxl/core: Set cxlmd->endpoint to NULL by default

[Li Ming <ming.li@zohomail.com>]

CXL testing environment can trigger following trace

 Oops: general protection fault, probably for non-canonical address 0xdffffc0000000092: 0000 [#1] SMP KASAN NOPTI
 KASAN: null-ptr-deref in range [0x0000000000000490-0x0000000000000497]
 RIP: 0010:cxl_dpa_to_region+0x105/0x1f0 [cxl_core]
 Call Trace:
  <TASK>
  cxl_event_trace_record+0xd1/0xa70 [cxl_core]
  __cxl_event_trace_record+0x12f/0x1e0 [cxl_core]
  cxl_mem_get_records_log+0x261/0x500 [cxl_core]
  cxl_mem_get_event_records+0x7c/0xc0 [cxl_core]
  cxl_mock_mem_probe+0xd38/0x1c60 [cxl_mock_mem]
  platform_probe+0x9d/0x130
  really_probe+0x1c8/0x960
  __driver_probe_device+0x187/0x3e0
  driver_probe_device+0x45/0x120
  __device_attach_driver+0x15d/0x280

commit 29317f8dc6ed ("cxl/mem: Introduce cxl_memdev_attach for CXL-dependent operation")
initializes cxlmd->endpoint to ERR_PTR(-ENXIO) in cxl_memdev_alloc().
However, cxl_dpa_to_region() treats a non-NULL cxlmd->endpoint as a
valid endpoint.

Across the CXL core, endpoint availability is generally determined by
checking whether it is NULL. Align with this convention by initializing
cxlmd->endpoint to NULL by default.

Fixes: 29317f8dc6ed ("cxl/mem: Introduce cxl_memdev_attach for CXL-dependent operation")
Signed-off-by: Li Ming <ming.li@zohomail.com>
---
 drivers/cxl/core/memdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index af3d0cc65138..41a507b5daa4 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -675,7 +675,7 @@ static struct cxl_memdev *cxl_memdev_alloc(struct cxl_dev_state *cxlds,
 	cxlmd->id = rc;
 	cxlmd->depth = -1;
 	cxlmd->attach = attach;
-	cxlmd->endpoint = ERR_PTR(-ENXIO);
+	cxlmd->endpoint = NULL;
 
 	dev = &cxlmd->dev;
 	device_initialize(dev);
-- 
2.43.0