linux-kernel - [PATCH 2/2] bus: mhi: ep: Add missing state_lock protection for mhi

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Message-Id: <20260203-reset_worker_deadlock-v1-2-7ed889b5bf19@oss.qualcomm.com>
Date: Tue, 03 Feb 2026 12:25:02 +0530
From: Sumit Kumar <sumit.kumar@....qualcomm.com>
To: Manivannan Sadhasivam <mani@...nel.org>, Alex Elder <elder@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: mhi@...ts.linux.dev, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Veerabhadrarao Badiganti <veerabhadrarao.badiganti@....qualcomm.com>,
        Subramanian Ananthanarayanan <subramanian.ananthanarayanan@....qualcomm.com>,
        Akhil Vinod <akhil.vinod@....qualcomm.com>,
        Sumit Kumar <sumit.kumar@....qualcomm.com>
Subject: [PATCH 2/2] bus: mhi: ep: Add missing state_lock protection for
 mhi_state accesses

The mhi_cntrl->mhi_state field should be protected by state_lock to
ensure atomic state transitions. However, mhi_ep_handle_syserr() and
mhi_ep_power_up() access mhi_state without holding this lock, which can
race with concurrent state transitions and lead to state corruption.

Add proper state_lock protection in both functions around their mhi_state
accesses.

Fixes: fb3a26b7e8af ("bus: mhi: ep: Add support for powering up the MHI endpoint stack")
Fixes: f7d0806bdb1b3 ("bus: mhi: ep: Add support for handling SYS_ERR condition")
Signed-off-by: Sumit Kumar <sumit.kumar@....qualcomm.com>
---
 drivers/bus/mhi/ep/main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
index 73597de373ef7e0c428bcbc126d63a9a97f95144..e9d14006453aa8b8999486a1cef17ca43f4cc4e1 100644
--- a/drivers/bus/mhi/ep/main.c
+++ b/drivers/bus/mhi/ep/main.c
@@ -1113,7 +1113,9 @@ void mhi_ep_handle_syserr(struct mhi_ep_cntrl *mhi_cntrl)
 	struct device *dev = &mhi_cntrl->mhi_dev->dev;
 	int ret;
 
+	mutex_lock(&mhi_cntrl->state_lock);
 	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_SYS_ERR);
+	mutex_unlock(&mhi_cntrl->state_lock);
 	if (ret)
 		return;
 
@@ -1148,7 +1150,9 @@ int mhi_ep_power_up(struct mhi_ep_cntrl *mhi_cntrl)
 	for (i = 0; i < mhi_cntrl->event_rings; i++)
 		mhi_ep_ring_init(&mhi_cntrl->mhi_event[i].ring, RING_TYPE_ER, i);
 
+	mutex_lock(&mhi_cntrl->state_lock);
 	mhi_cntrl->mhi_state = MHI_STATE_RESET;
+	mutex_unlock(&mhi_cntrl->state_lock);
 
 	/* Set AMSS EE before signaling ready state */
 	mhi_ep_mmio_set_env(mhi_cntrl, MHI_EE_AMSS);

-- 
2.34.1