netdev - Re: [PATCH 1/2] ath9k: hold RCU lock when calling ieee80211_find_sta_by

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Message-ID: <00f1fb03-defc-89be-7629-69a0d9f659d4@nbd.name>
Date:   Fri, 12 Feb 2021 07:31:28 +0100
From:   Felix Fietkau <nbd@....name>
To:     Shuah Khan <skhan@...uxfoundation.org>, kvalo@...eaurora.org,
        davem@...emloft.net, kuba@...nel.org
Cc:     ath9k-devel@....qualcomm.com, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] ath9k: hold RCU lock when calling
 ieee80211_find_sta_by_ifaddr()

On 2021-02-12 03:13, Shuah Khan wrote:
> ieee80211_find_sta_by_ifaddr() must be called under the RCU lock and
> the resulting pointer is only valid under RCU lock as well.
> 
> Fix ath_tx_process_buffer() to hold RCU read lock before it calls
> ieee80211_find_sta_by_ifaddr() and release it when the resulting
> pointer is no longer needed.
> 
> This problem was found while reviewing code to debug RCU warn from
> ath10k_wmi_tlv_parse_peer_stats_info() and a subsequent manual audit
> of other callers of ieee80211_find_sta_by_ifaddr() that don't hold
> RCU read lock.
> 
> Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
This patch seems unnecessary as well. All callers of
ath_tx_process_buffer seem to hold the RCU read lock already.

- Felix