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From:   Kalle Valo <kvalo@kernel.org>
To:     Niels Dossche <dossche.niels@gmail.com>
Cc:     ath11k@lists.infradead.org, linux-wireless@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Carl Huang <cjhuang@codeaurora.org>
Subject: Re: [PATCH] ath11k: acquire ab->base_lock in unassign when finding the peer by addr
References: <20220314215253.92658-1-dossche.niels@gmail.com>
Date:   Mon, 21 Mar 2022 12:45:25 +0200
In-Reply-To: <20220314215253.92658-1-dossche.niels@gmail.com> (Niels Dossche's
        message of "Mon, 14 Mar 2022 22:52:53 +0100")
Message-ID: <87zgljmvne.fsf@kernel.org>
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Niels Dossche <dossche.niels@gmail.com> writes:

> ath11k_peer_find_by_addr states via lockdep that ab->base_lock must be
> held when calling that function in order to protect the list. All
> callers except ath11k_mac_op_unassign_vif_chanctx have that lock
> acquired when calling ath11k_peer_find_by_addr. That lock is also not
> transitively held by a path towards ath11k_mac_op_unassign_vif_chanctx.
> The solution is to acquire the lock when calling
> ath11k_peer_find_by_addr inside ath11k_mac_op_unassign_vif_chanctx.
>
> Fixes: 701e48a43e15 ("ath11k: add packet log support for QCA6390")
> Signed-off-by: Niels Dossche <dossche.niels@gmail.com>
> ---
>  drivers/net/wireless/ath/ath11k/mac.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
> index 07f499d5ec92..5db2333478a2 100644
> --- a/drivers/net/wireless/ath/ath11k/mac.c
> +++ b/drivers/net/wireless/ath/ath11k/mac.c
> @@ -7077,9 +7077,15 @@ ath11k_mac_op_unassign_vif_chanctx(struct ieee80211_hw *hw,
>  	WARN_ON(!arvif->is_started);
>  
>  	if (ab->hw_params.vdev_start_delay &&
> -	    arvif->vdev_type == WMI_VDEV_TYPE_MONITOR &&
> -	    ath11k_peer_find_by_addr(ab, ar->mac_addr))
> -		ath11k_peer_delete(ar, arvif->vdev_id, ar->mac_addr);
> +	    arvif->vdev_type == WMI_VDEV_TYPE_MONITOR) {
> +		struct ath11k_peer *peer;

In the pending branch I moved the declaration to the beginning of the
function and added this to the commit log:

"I am currently working on a static analyser to detect missing locks and
this was a reported case. I manually verified the report by looking at
the code, but I do not have real hardware so this is compile tested
only."

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