[ Upstream commit db66abeea3aefed481391ecc564fb7b7fb31d742 ] If userspace installs a lot of multicast groups very quickly, then we may run out of command queue space as we send the updates in an asynchronous fashion (due to locking concerns), and the CPU can create them faster than the firmware can process them. This is true even when mac80211 has a work struct that gets scheduled. Fix this by synchronizing with the firmware after sending all those commands - outside of the iteration we can send a synchronous echo command that just has the effect of the CPU waiting for the prior asynchronous commands to finish. This also will cause fewer of the commands to be sent to the firmware overall, because the work will only run once when rescheduled multiple times while it's running. Link: https://bugzilla.kernel.org/show_bug.cgi?id=213649 Suggested-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com> Reported-by: Maximilian Ernestus <maximilian@ernestus.de> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Luca Coelho <luciano.coelho@intel.com> Link: https://lore.kernel.org/r/iwlwifi.20211204083238.51aea5b79ea4.I88a44798efda16e9fe480fb3e94224931d311b29@changeid Signed-off-by: Luca Coelho <luciano.coelho@intel.com> Signed-off-by: Sasha Levin <sashal@kernel.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.
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