From 4047bcfff03f9bf68eb1288e3c2c9f0d83145d8e Mon Sep 17 00:00:00 2001 From: Manivannan Sadhasivam Date: Wed, 28 Dec 2022 21:47:03 +0530 Subject: [PATCH] bus: mhi: ep: Move chan->lock to the start of processing queued ch ring commit 289199984ca003667af794abd5b3a7c74fe99246 upstream. There is a good chance that while the channel ring gets processed, the STOP or RESET command for the channel might be received from the MHI host. In those cases, the entire channel ring processing needs to be protected by chan->lock to prevent the race where the corresponding channel ring might be reset. While at it, let's also add a sanity check to make sure that the ring is started before processing it. Because, if the STOP/RESET command gets processed while mhi_ep_ch_ring_worker() waited for chan->lock, the ring would've been reset. Cc: # 5.19 Fixes: 9dd5d0b7c99e ("bus: mhi: ep: Add support for processing channel rings") Signed-off-by: Manivannan Sadhasivam Reviewed-by: Jeffrey Hugo Link: https://lore.kernel.org/r/20221228161704.255268-6-manivannan.sadhasivam@linaro.org Signed-off-by: Manivannan Sadhasivam Signed-off-by: Greg Kroah-Hartman --- drivers/bus/mhi/ep/main.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c index 2b3a3b56e2807..883bf79be57ef 100644 --- a/drivers/bus/mhi/ep/main.c +++ b/drivers/bus/mhi/ep/main.c @@ -723,24 +723,37 @@ static void mhi_ep_ch_ring_worker(struct work_struct *work) list_del(&itr->node); ring = itr->ring; + chan = &mhi_cntrl->mhi_chan[ring->ch_id]; + mutex_lock(&chan->lock); + + /* + * The ring could've stopped while we waited to grab the (chan->lock), so do + * a sanity check before going further. + */ + if (!ring->started) { + mutex_unlock(&chan->lock); + kfree(itr); + continue; + } + /* Update the write offset for the ring */ ret = mhi_ep_update_wr_offset(ring); if (ret) { dev_err(dev, "Error updating write offset for ring\n"); + mutex_unlock(&chan->lock); kfree(itr); continue; } /* Sanity check to make sure there are elements in the ring */ if (ring->rd_offset == ring->wr_offset) { + mutex_unlock(&chan->lock); kfree(itr); continue; } el = &ring->ring_cache[ring->rd_offset]; - chan = &mhi_cntrl->mhi_chan[ring->ch_id]; - mutex_lock(&chan->lock); dev_dbg(dev, "Processing the ring for channel (%u)\n", ring->ch_id); ret = mhi_ep_process_ch_ring(ring, el); if (ret) { -- 2.39.5