linux-kernel - [PATCH v4 3/4] bus: mhi: host: Avoid processing buffer and event of a disable channel

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Date:   Tue, 14 Nov 2023 13:27:40 +0800
From:   Qiang Yu <quic_qianyu@...cinc.com>
To:     mani@...nel.org, quic_jhugo@...cinc.com
Cc:     mhi@...ts.linux.dev, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_cang@...cinc.com,
        quic_mrana@...cinc.com, Qiang Yu <quic_qianyu@...cinc.com>
Subject: [PATCH v4 3/4] bus: mhi: host: Avoid processing buffer and event of a disable channel

MHI channel state is protected by mhi_chan->lock. Hence, after core drops
mhi_chan->lock during processing xfer event, it can not prevent channel
state being changed if client closes channel or driver is removed at this
time. So let's check mhi channel state after getting chan->lock again to
avoid queuing buffer to a disabled channel in xfer callback and stop
processing event of the disabled channel.

Signed-off-by: Qiang Yu <quic_qianyu@...cinc.com>
---
 drivers/bus/mhi/host/main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index c4215b0..33f27e2 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -671,6 +671,8 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl,
 			}
 
 			read_lock_bh(&mhi_chan->lock);
+			if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED)
+				goto end_process_tx_event;
 		}
 		break;
 	} /* CC_EOT */
@@ -1210,6 +1212,10 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan,
 
 	/* Protect accesses for reading and incrementing WP */
 	write_lock_bh(&mhi_chan->lock);
+	if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED) {
+		write_unlock_bh(&mhi_chan->lock);
+		return -EINVAL;
+	}
 
 	buf_ring = &mhi_chan->buf_ring;
 	tre_ring = &mhi_chan->tre_ring;
-- 
2.7.4