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ieee80211_txq_purge() calls fq_tin_reset() and ieee80211_purge_tx_queue(); Both are then calling ieee80211_free_txskb(). Which can decide to TX the skb again. There are at least two ways to get a deadlock: 1) When we have a TDLS teardown packet queued in either tin or frags ieee80211_tdls_td_tx_handle() will call ieee80211_subif_start_xmit() while we still hold fq->lock. ieee80211_txq_enqueue() will thus deadlock. 2) A variant of the above happens if aggregation is up and running: In that case ieee80211_iface_work() will deadlock with the original task: The original tasks already holds fq->lock and tries to get sta->lock after kicking off ieee80211_iface_work(). But the worker can get sta->lock prior to the original task and will then spin for fq->lock. Avoid these deadlocks by not sending out any skbs when called via ieee80211_free_txskb(). Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de> Link: https://lore.kernel.org/r/20220915124120.301918-1-alexander@wetzel-home.de 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.