Jiri Pirko 30bab7cdb5 net: devlink: make sure that devlink_try_get() works with valid pointer during xarray iteration
Remove dependency on devlink_mutex during devlinks xarray iteration.

The reason is that devlink_register/unregister() functions taking
devlink_mutex would deadlock during devlink reload operation of devlink
instance which registers/unregisters nested devlink instances.

The devlinks xarray consistency is ensured internally by xarray.
There is a reference taken when working with devlink using
devlink_try_get(). But there is no guarantee that devlink pointer
picked during xarray iteration is not freed before devlink_try_get()
is called.

Make sure that devlink_try_get() works with valid pointer.
Achieve it by:
1) Splitting devlink_put() so the completion is sent only
   after grace period. Completion unblocks the devlink_unregister()
   routine, which is followed-up by devlink_free()
2) During devlinks xa_array iteration, get devlink pointer from xa_array
   holding RCU read lock and taking reference using devlink_try_get()
   before unlock.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-07-26 13:50:50 -07:00
2022-07-17 13:30:22 -07:00

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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