f34f2a18e4
commit f1b4e32aca0811aa011c76e5d6cf2fa19224b386 upstream.
In commit d5f9023fa61e ("can: bcm: delay release of struct bcm_op
after synchronize_rcu()") Thadeu Lima de Souza Cascardo introduced two
synchronize_rcu() calls in bcm_release() (only once at socket close)
and in bcm_delete_rx_op() (called on removal of each single bcm_op).
Unfortunately this slow removal of the bcm_op's affects user space
applications like cansniffer where the modification of a filter
removes 2048 bcm_op's which blocks the cansniffer application for
40(!) seconds.
In commit 181d4447905d ("can: gw: use call_rcu() instead of costly
synchronize_rcu()") Eric Dumazet replaced the synchronize_rcu() calls
with several call_rcu()'s to safely remove the data structures after
the removal of CAN ID subscriptions with can_rx_unregister() calls.
This patch adopts Erics approach for the can-bcm which should be
applicable since the removal of tasklet_kill() in bcm_remove_op() and
the introduction of the HRTIMER_MODE_SOFT timer handling in Linux 5.4.
Fixes: d5f9023fa61e ("can: bcm: delay release of struct bcm_op after synchronize_rcu()") # >= 5.4
Link: https://lore.kernel.org/all/20220520183239.19111-1-socketcan@hartkopp.net
Cc: stable@vger.kernel.org
Cc: Eric Dumazet <edumazet@google.com>
Cc: Norbert Slusarek <nslusarek@gmx.net>
Cc: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.