linux-kernel - [PATCH v2 2/2] bus: mhi: host: Take irqsave lock after TRE is generated

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Date:   Wed, 13 Sep 2023 16:47:41 +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, Hemant Kumar <quic_hemantk@...cinc.com>,
        Lazarus Motha <quic_lmotha@...cinc.com>,
        Qiang Yu <quic_qianyu@...cinc.com>
Subject: [PATCH v2 2/2] bus: mhi: host: Take irqsave lock after TRE is generated

From: Hemant Kumar <quic_hemantk@...cinc.com>

Take irqsave lock after TRE is generated to avoid deadlock due to core
getting interrupts enabled as local_bh_enable must not be called with
irqs disabled based on upstream patch.

Signed-off-by: Hemant Kumar <quic_hemantk@...cinc.com>
Signed-off-by: Lazarus Motha <quic_lmotha@...cinc.com>
Signed-off-by: Qiang Yu <quic_qianyu@...cinc.com>
---
 drivers/bus/mhi/host/main.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index 13c4b89..8accdfd 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -1124,17 +1124,15 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
 	if (unlikely(MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)))
 		return -EIO;
 
-	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);
-
 	ret = mhi_is_ring_full(mhi_cntrl, tre_ring);
-	if (unlikely(ret)) {
-		ret = -EAGAIN;
-		goto exit_unlock;
-	}
+	if (unlikely(ret))
+		return -EAGAIN;
 
 	ret = mhi_gen_tre(mhi_cntrl, mhi_chan, buf_info, mflags);
 	if (unlikely(ret))
-		goto exit_unlock;
+		return ret;
+
+	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);
 
 	/* Packet is queued, take a usage ref to exit M3 if necessary
 	 * for host->device buffer, balanced put is done on buffer completion
@@ -1154,7 +1152,6 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
 	if (dir == DMA_FROM_DEVICE)
 		mhi_cntrl->runtime_put(mhi_cntrl);
 
-exit_unlock:
 	read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);
 
 	return ret;
-- 
2.7.4