diff mbox series

[v3,2/4] bus: mhi: host: Drop chan lock before queuing buffers

Message ID 1699341365-47737-3-git-send-email-quic_qianyu@quicinc.com
State Superseded
Headers show
Series bus: mhi: host: Add lock to avoid race when ringing channel DB | expand

Commit Message

Qiang Yu Nov. 7, 2023, 7:16 a.m. UTC
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.

Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
---
 drivers/bus/mhi/host/main.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index c9415b0..a236dc2 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -643,6 +643,8 @@  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);
 
@@ -668,6 +670,8 @@  static int parse_xfer_event(struct mhi_controller *mhi_cntrl,
 					kfree(buf_info->cb_buf);
 				}
 			}
+
+			read_lock_bh(&mhi_chan->lock);
 		}
 		break;
 	} /* CC_EOT */