linux-kernel - [PATCH v8 7/9] bus: mhi: core: Check channel execution environment before issuing reset

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Message-Id: <1617311778-1254-8-git-send-email-bbhatt@codeaurora.org>
Date:   Thu,  1 Apr 2021 14:16:16 -0700
From:   Bhaumik Bhatt <bbhatt@...eaurora.org>
To:     manivannan.sadhasivam@...aro.org
Cc:     linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
        jhugo@...eaurora.org, linux-kernel@...r.kernel.org,
        carl.yin@...ctel.com, naveen.kumar@...ctel.com,
        loic.poulain@...aro.org, Bhaumik Bhatt <bbhatt@...eaurora.org>
Subject: [PATCH v8 7/9] bus: mhi: core: Check channel execution environment before issuing reset

A client can attempt to unprepare certain channels for transfer even
after the execution environment they are supposed to run in has changed.
In the event that happens, the device need not be notified of the reset
and the host can proceed with clean up for the channel context and
memory allocated for it on the host as the device will no longer be able
to respond to such a request.

Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
Reviewed-by: Hemant Kumar <hemantk@...eaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/bus/mhi/core/main.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 989a2a8..04480fd 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -1329,6 +1329,12 @@ static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
 
 	mutex_lock(&mhi_chan->mutex);
 
+	if (!(BIT(mhi_cntrl->ee) & mhi_chan->ee_mask)) {
+		dev_dbg(dev, "Current EE: %s Required EE Mask: 0x%x\n",
+			TO_MHI_EXEC_STR(mhi_cntrl->ee), mhi_chan->ee_mask);
+		goto exit_unprepare_channel;
+	}
+
 	/* no more processing events for this channel */
 	ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
 				       MHI_CH_STATE_TYPE_RESET);
@@ -1336,6 +1342,11 @@ static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
 		dev_err(dev, "%d: Failed to reset channel, still resetting\n",
 			mhi_chan->chan);
 
+exit_unprepare_channel:
+	write_lock_irq(&mhi_chan->lock);
+	mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
+	write_unlock_irq(&mhi_chan->lock);
+
 	if (!mhi_chan->offload_ch) {
 		mhi_reset_chan(mhi_cntrl, mhi_chan);
 		mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);
-- 
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