From 3c5ec66b4b3f6816f3a6161538672e389e537690 Mon Sep 17 00:00:00 2001 From: Qiang Yu Date: Mon, 11 Dec 2023 14:42:52 +0800 Subject: [PATCH] bus: mhi: host: Drop chan lock before queuing buffers commit 01bd694ac2f682fb8017e16148b928482bc8fa4b upstream. 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. Cc: # 5.7 Fixes: 1d3173a3bae7 ("bus: mhi: core: Add support for processing events from client device") Signed-off-by: Qiang Yu Reviewed-by: Jeffrey Hugo Tested-by: Jeffrey Hugo Reviewed-by: Manivannan Sadhasivam Link: https://lore.kernel.org/r/1702276972-41296-3-git-send-email-quic_qianyu@quicinc.com [mani: added fixes tag and cc'ed stable] Signed-off-by: Manivannan Sadhasivam Signed-off-by: Greg Kroah-Hartman --- drivers/bus/mhi/host/main.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c index 3743b43eceda..a60ba20b7d8b 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 */