From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kalle Valo Date: Tue, 02 Feb 2021 04:32:44 +0000 Subject: Re: [PATCH] ath11k: fix a locking bug in ath11k_mac_op_start() Message-Id: <875z3b84yb.fsf@codeaurora.org> List-Id: References: <896a68dd-02ec-4fe3-3fbf-ec1bd2decefe@eero.com> In-Reply-To: <896a68dd-02ec-4fe3-3fbf-ec1bd2decefe@eero.com> (Peter Oh's message of "Mon, 1 Feb 2021 13:47:27 -0800") MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Peter Oh Cc: linux-wireless@vger.kernel.org, Carl Huang , kernel-janitors@vger.kernel.org, ath11k@lists.infradead.org, Dan Carpenter Peter Oh writes: > On 2/1/21 4:24 AM, Dan Carpenter wrote: >> This error path leads to a Smatch warning: >> >> drivers/net/wireless/ath/ath11k/mac.c:4269 ath11k_mac_op_start() >> error: double unlocked '&ar->conf_mutex' (orig line 4251) >> >> We're not holding the lock when we do the "goto err;" so it leads to a >> double unlock. We should hold the lock because the error path sets >> "ar->state" so the right fix is to take the lock before doing the goto. >> >> Fixes: c83c500b55b6 ("ath11k: enable idle power save mode") >> Signed-off-by: Dan Carpenter >> --- >> drivers/net/wireless/ath/ath11k/mac.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireles= s/ath/ath11k/mac.c >> index c1608f64ea95..12e981e9e3d7 100644 >> --- a/drivers/net/wireless/ath/ath11k/mac.c >> +++ b/drivers/net/wireless/ath/ath11k/mac.c >> @@ -4259,6 +4259,7 @@ static int ath11k_mac_op_start(struct ieee80211_hw= *hw) >> 1, pdev->pdev_id); >> if (ret) { >> ath11k_err(ab, "failed to enable idle ps: %d\n", ret); >> + mutex_lock(&ar->conf_mutex); >> goto err; >> } >> } > > It seems moving idle_ps condition in between ath11k_wmi_pdev_lro_cfg() > and mutex_unlock() > =C2=A0is a better way in this case. I agree. In Dan's approach I'm worried about the race when we unlock and lock again, the state can change in that case. --=20 https://patchwork.kernel.org/project/linux-wireless/list/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatc= hes