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cxl/mem: Do not rely on device_add() side effects for dev_set_name() failures 

While device_add() will happen to catch dev_set_name() failures it is a
broken pattern to follow given that the core may try to fall back to a
different name.

Add explicit checking for dev_set_name() failures to be cleaned up by
put_device(). Skip cdev_device_add() and proceed directly to
put_device() if the name set fails.

This type of bug is easier to see if 'alloc' is split from 'add'
operations that require put_device() on failure. So cxl_memdev_alloc()
is split out as a result.

Fixes: b39cb1052a ("cxl/mem: Register CXL memX devices")
Reported-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/161728760514.2474381.1163928273337158134.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2021-04-01 07:33:25 -07:00
parent 5877515912
commit 1c3333a28d
1 changed files with 29 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
drivers/cxl/mem.c
View File

@ -1180,7 +1180,7 @@ static void cxl_memdev_unregister(void *_cxlmd)
put_device(dev);
}
static int cxl_mem_add_memdev(struct cxl_mem *cxlm)
static struct cxl_memdev *cxl_memdev_alloc(struct cxl_mem *cxlm)
{
struct pci_dev *pdev = cxlm->pdev;
struct cxl_memdev *cxlmd;
@ -1190,11 +1190,11 @@ static int cxl_mem_add_memdev(struct cxl_mem *cxlm)
cxlmd = kzalloc(sizeof(*cxlmd), GFP_KERNEL);
if (!cxlmd)
return -ENOMEM;
return ERR_PTR(-ENOMEM);
rc = ida_alloc_range(&cxl_memdev_ida, 0, CXL_MEM_MAX_DEVS, GFP_KERNEL);
if (rc < 0)
goto err_id;
goto err;
cxlmd->id = rc;
dev = &cxlmd->dev;
@ -1203,10 +1203,31 @@ static int cxl_mem_add_memdev(struct cxl_mem *cxlm)
dev->bus = &cxl_bus_type;
dev->devt = MKDEV(cxl_mem_major, cxlmd->id);
dev->type = &cxl_memdev_type;
dev_set_name(dev, "mem%d", cxlmd->id);
cdev = &cxlmd->cdev;
cdev_init(cdev, &cxl_memdev_fops);
return cxlmd;
err:
kfree(cxlmd);
return ERR_PTR(rc);
}
static int cxl_mem_add_memdev(struct cxl_mem *cxlm)
{
struct cxl_memdev *cxlmd;
struct device *dev;
struct cdev *cdev;
int rc;
cxlmd = cxl_memdev_alloc(cxlm);
if (IS_ERR(cxlmd))
return PTR_ERR(cxlmd);
dev = &cxlmd->dev;
rc = dev_set_name(dev, "mem%d", cxlmd->id);
if (rc)
goto err;
/*
* Activate ioctl operations, no cxl_memdev_rwsem manipulation
@ -1214,23 +1235,21 @@ static int cxl_mem_add_memdev(struct cxl_mem *cxlm)
*/
cxlmd->cxlm = cxlm;
cdev = &cxlmd->cdev;
rc = cdev_device_add(cdev, dev);
if (rc)
goto err_add;
goto err;
return devm_add_action_or_reset(dev->parent, cxl_memdev_unregister,
cxlmd);
err_add:
err:
/*
* The cdev was briefly live, shutdown any ioctl operations that
* saw that state.
*/
cxl_memdev_shutdown(cxlmd);
ida_free(&cxl_memdev_ida, cxlmd->id);
err_id:
kfree(cxlmd);
put_device(dev);
return rc;
}