Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:36596 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750966AbdEaK1U (ORCPT ); Wed, 31 May 2017 06:27:20 -0400 From: Kalle Valo To: Jia-Ju Bai Cc: Larry.Finger@lwfinger.net, linux-wireless@vger.kernel.org, b43-dev@lists.infradead.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] b43legacy: Fix a sleep-in-atomic bug in b43legacy_op_bss_info_changed References: <1496225353-5544-1-git-send-email-baijiaju1990@163.com> Date: Wed, 31 May 2017 13:26:43 +0300 In-Reply-To: <1496225353-5544-1-git-send-email-baijiaju1990@163.com> (Jia-Ju Bai's message of "Wed, 31 May 2017 18:09:13 +0800") Message-ID: <877f0xnwyk.fsf@kamboji.qca.qualcomm.com> (sfid-20170531_122806_843345_65F79250) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-wireless-owner@vger.kernel.org List-ID: Jia-Ju Bai writes: > The driver may sleep under a spin lock, and the function call path is: > b43legacy_op_bss_info_changed (acquire the lock by spin_lock_irqsave) > b43legacy_synchronize_irq > synchronize_irq --> may sleep > > To fix it, the lock is released before b43legacy_synchronize_irq, and the > lock is acquired again after this function. > > Signed-off-by: Jia-Ju Bai > --- > drivers/net/wireless/broadcom/b43legacy/main.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/net/wireless/broadcom/b43legacy/main.c b/drivers/net/wireless/broadcom/b43legacy/main.c > index f1e3dad..31ead21 100644 > --- a/drivers/net/wireless/broadcom/b43legacy/main.c > +++ b/drivers/net/wireless/broadcom/b43legacy/main.c > @@ -2859,7 +2859,9 @@ static void b43legacy_op_bss_info_changed(struct ieee80211_hw *hw, > b43legacy_write32(dev, B43legacy_MMIO_GEN_IRQ_MASK, 0); > > if (changed & BSS_CHANGED_BSSID) { > + spin_unlock_irqrestore(&wl->irq_lock, flags); > b43legacy_synchronize_irq(dev); > + spin_lock_irqsave(&wl->irq_lock, flags); To me this looks like a fragile workaround and not a real fix. You can easily add new race conditions with releasing the lock like this. -- Kalle Valo