Dan Williams 5877515912 cxl/mem: Fix synchronization mechanism for device removal vs ioctl operations
The percpu_ref to gate whether cxl_memdev_ioctl() is free to use the
driver context (@cxlm) to issue I/O is overkill, implemented incorrectly
(missing a device reference before accessing the percpu_ref), and the
complexities of shutting down a percpu_ref contributed to a bug in the
error unwind in cxl_mem_add_memdev() (missing put_device() to be fixed
separately).

Use an rwsem to explicitly synchronize the usage of cxlmd->cxlm, and add
the missing reference counting for cxlmd in cxl_memdev_open() and
cxl_memdev_release_file().

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/161728759948.2474381.17481500816783671817.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2021-04-06 11:41:30 -07:00
2021-01-24 14:27:20 +01:00
2021-03-02 17:25:46 -07:00
2021-02-26 09:41:03 -08:00
2021-02-26 09:41:03 -08:00
2021-02-26 09:41:03 -08:00
2021-03-05 17:33:41 -08:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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