Lockdep on 6.4-rc on ThinkPad X1 Carbon 5th says
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WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
6.4.0-rc5 #1 Not tainted
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kworker/3:1/49 [HC0[0]:SC0[4]:HE1:SE0] is trying to acquire:
ffff8881066fa368 (&mvm_sta->deflink.lq_sta.rs_drv.pers.lock){+.+.}-{2:2}, at: rs_drv_get_rate+0x46/0xe7
and this task is already holding:
ffff8881066f80a8 (&sta->rate_ctrl_lock){+.-.}-{2:2}, at: rate_control_get_rate+0xbd/0x126
which would create a new lock dependency:
(&sta->rate_ctrl_lock){+.-.}-{2:2} -> (&mvm_sta->deflink.lq_sta.rs_drv.pers.lock){+.+.}-{2:2}
but this new dependency connects a SOFTIRQ-irq-safe lock:
(&sta->rate_ctrl_lock){+.-.}-{2:2}
etc. etc. etc.
Changing the spin_lock() in rs_drv_get_rate() to spin_lock_bh() was not
enough to pacify lockdep, but changing them all on pers.lock has worked.
Fixes: a8938bc881 ("wifi: iwlwifi: mvm: Add locking to the rate read flow")
Signed-off-by: Hugh Dickins <hughd@google.com>
Link: https://lore.kernel.org/r/79ffcc22-9775-cb6d-3ffd-1a517c40beef@google.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
f1a0898b5d