mwifiex: Fix possible ABBA deadlock

Quoting Jia-Ju Bai <[email protected]>:

  mwifiex_dequeue_tx_packet()
     spin_lock_bh(&priv->wmm.ra_list_spinlock); --> Line 1432 (Lock A)
     mwifiex_send_addba()
       spin_lock_bh(&priv->sta_list_spinlock); --> Line 608 (Lock B)

  mwifiex_process_sta_tx_pause()
     spin_lock_bh(&priv->sta_list_spinlock); --> Line 398 (Lock B)
     mwifiex_update_ralist_tx_pause()
       spin_lock_bh(&priv->wmm.ra_list_spinlock); --> Line 941 (Lock A)

Similar report for mwifiex_process_uap_tx_pause().

While the locking expectations in this driver are a bit unclear, the
Fixed commit only intended to protect the sta_ptr, so we can drop the
lock as soon as we're done with it.

IIUC, this deadlock cannot actually happen, because command event
processing (which calls mwifiex_process_sta_tx_pause()) is
sequentialized with TX packet processing (e.g.,
mwifiex_dequeue_tx_packet()) via the main loop (mwifiex_main_process()).
But it's good not to leave this potential issue lurking.

Fixes: f0f7c2275fb9 ("mwifiex: minor cleanups w/ sta_list_spinlock in cfg80211.c")
Cc: Douglas Anderson <[email protected]>
Reported-by: TOTE Robot <[email protected]>
Link: https://lore.kernel.org/linux-wireless/[email protected]/
Signed-off-by: Brian Norris <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Signed-off-by: Kalle Valo <[email protected]>
Link: https://lore.kernel.org/r/YaV0pllJ5p/[email protected]

0 files changed, 0 insertions, 0 deletions