From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8E9C910A2B; Sat, 16 Dec 2023 05:19:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D8Rwtikr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85618C433C8; Sat, 16 Dec 2023 05:19:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702703961; bh=geWMBLcp6sf1ms/3Xd1oNOeH2gSFO3bsbIdjbrF8pBU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=D8RwtikrCgR7IeIf7effE0TXN2gDjVDQjkMDLuYViPS7qJV/Q5yClH/ecL+nhocjc dH7gc6QhfrFKI7Auns+lzUfAQm8tqkWphKmEsXaIfpGP/8WxZiIJLdVgSa3LDz+jLY l9lUGVTUyVUj7UJhnYJrDeIxRQjZgl7DDuIEWApuLzN8/6xzwKunEKlj6xxiKGVD29 oKDguXIFl9sPRsWLUK1XNgsfcd+mMl8CGUMcji03D8Cn1jqolY4eNNyaL/XHQBNwzb AGMeNDg1RSJSOB3HeBlAJuHLgglU/W9W4xhiD97bqdK3StzdbMNBPppOu39ez7Ors6 ILzEUHamsW2JA== Date: Sat, 16 Dec 2023 10:49:08 +0530 From: Manivannan Sadhasivam To: Qiang Yu Cc: quic_jhugo@quicinc.com, mhi@lists.linux.dev, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, quic_cang@quicinc.com, quic_mrana@quicinc.com Subject: Re: [PATCH v5 2/2] bus: mhi: host: Drop chan lock before queuing buffers Message-ID: <20231216051908.GB3405@thinkpad> References: <1702276972-41296-1-git-send-email-quic_qianyu@quicinc.com> <1702276972-41296-3-git-send-email-quic_qianyu@quicinc.com> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1702276972-41296-3-git-send-email-quic_qianyu@quicinc.com> On Mon, Dec 11, 2023 at 02:42:52PM +0800, Qiang Yu wrote: > Ensure read and write locks for the channel are not taken in succession by > dropping the read lock from parse_xfer_event() such that a callback given > to client can potentially queue buffers and acquire the write lock in that > process. Any queueing of buffers should be done without channel read lock > acquired as it can result in multiple locks and a soft lockup. > Cc: # 5.7 Fixes: 1d3173a3bae7 ("bus: mhi: core: Add support for processing events from client device") > Signed-off-by: Qiang Yu Reviewed-by: Manivannan Sadhasivam - Mani > --- > drivers/bus/mhi/host/main.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c > index 32021fe..25f98d6 100644 > --- a/drivers/bus/mhi/host/main.c > +++ b/drivers/bus/mhi/host/main.c > @@ -642,6 +642,8 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl, > mhi_del_ring_element(mhi_cntrl, tre_ring); > local_rp = tre_ring->rp; > > + read_unlock_bh(&mhi_chan->lock); > + > /* notify client */ > mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result); > > @@ -667,6 +669,8 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl, > kfree(buf_info->cb_buf); > } > } > + > + read_lock_bh(&mhi_chan->lock); > } > break; > } /* CC_EOT */ > -- > 2.7.4 > > -- மணிவண்ணன் சதாசிவம்