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  • Johannes Berg's avatar
    mac80211: proper STA info locking · 07346f81
    Johannes Berg authored
    As discussed earlier, we can unify locking in struct sta_info
    and use just a single spinlock protecting all members of the
    structure that need protection. Many don't, but one of the
    especially bad ones is the 'flags' member that can currently
    be clobbered when RX and TX is being processed on different
    CPUs at the same time.
    Because having four spinlocks for different, mostly exclusive
    parts of a single structure is overkill, this patch also kills
    the ampdu and mesh plink spinlocks and uses just a single one
    for everything. Because none of the spinlocks are nested, this
    is safe.
    It remains to be seen whether or not we should make the sta
    flags use atomic bit operations instead, for now though this
    is a safe thing and using atomic operations instead will be
    very simple using the new static inline functions this patch
    introduces for accessing sta->flags.
    Since spin_lock_bh() is used with this lock, there shouldn't
    be any contention even if aggregation is enabled at around the
    same time as both requires frame transmission/reception which
    is in a bh context.
    Signed-off-by: default avatarJohannes Berg <>
    Cc: Tomas Winkler <>
    Cc: Ron Rindjunsky <>
    Cc: Luis Carlos Cobo <>
    Signed-off-by: default avatarJohn W. Linville <>