Re: [PATCH v5.1-rc] iwlwifi: make locking in iwl_mvm_tx_mpdu() BH-safe
From: Johannes Berg
Date: Mon Apr 15 2019 - 07:10:57 EST
On Mon, 2019-04-15 at 13:03 +0200, Jiri Kosina wrote:
(FWIW, would be good to cc linux-wireless, but no need for linux-kernel
I guess :-) )
> iwl_mvm_sta->lock can be taken from BH, and therefore BH must be disabled if
> taking it from other contexts.
>
> This fixes the lockdep warning below.
I don't think this is the right fix.
The only problem is this path:
> SOFTIRQ-ON-W at:
> _raw_spin_lock+0x35/0x50
> iwl_mvm_tx_mpdu+0xae/0x5f0 [iwlmvm]
> iwl_mvm_tx_skb+0x200/0x470 [iwlmvm]
> iwl_mvm_mac_itxq_xmit+0xd5/0x1f0 [iwlmvm]
> iwl_mvm_add_new_dqa_stream_wk+0x34c/0x910 [iwlmvm]
> process_one_work+0x1f0/0x5b0
which I believe we just made use local_bh_disable() since there are
other reasons as well for that, IIRC.
Yes, here's the fix:
https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers.git/commit/?id=f5ae2f932e2f8f4f79796f44832ae8fca26f188a
It's on the way upstream.
Thanks for the patch/report though!
johannes