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In case we got a fw restart while roaming from encrypted AP to non-encrypted one, we might end up with hitting a warning on the pending counter crypto_tx_tailroom_pending_dec having a non-zero value. The following comment taken from net/mac80211/key.c explains the rational for the delayed tailroom needed: /* * The reason for the delayed tailroom needed decrementing is to * make roaming faster: during roaming, all keys are first deleted * and then new keys are installed. The first new key causes the * crypto_tx_tailroom_needed_cnt to go from 0 to 1, which invokes * the cost of synchronize_net() (which can be slow). Avoid this * by deferring the crypto_tx_tailroom_needed_cnt decrementing on * key removal for a while, so if we roam the value is larger than * zero and no 0->1 transition happens. * * The cost is that if the AP switching was from an AP with keys * to one without, we still allocate tailroom while it would no * longer be needed. However, in the typical (fast) roaming case * within an ESS this usually won't happen. */ The next flow lead to the warning eventually reported as a bug: 1. Disconnect from encrypted AP 2. Set crypto_tx_tailroom_pending_dec = 1 for the key 3. Schedule work 4. Reconnect to non-encrypted AP 5. Add a new key, setting the tailroom counter = 1 6. Got FW restart while pending counter is set ---> hit the warning While on it, the ieee80211_reset_crypto_tx_tailroom() func was merged into its single caller ieee80211_reenable_keys (previously called ieee80211_enable_keys). Also, we reset the crypto_tx_tailroom_pending_dec and remove the counters warning as we just reset both. Signed-off-by: Lior Cohen <lior2.cohen@intel.com> Signed-off-by: Luca Coelho <luciano.coelho@intel.com> Link: https://lore.kernel.org/r/20190830112451.21655-7-luca@coelho.fi Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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.