From: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org
commit 8d6a1fea53864cd9545741f48f4ae4df804db557 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: stable@vger.kernel.org # 5.19 Fixes: 03c0bb8ec983 ("bus: mhi: ep: Add support for processing channel rings") Signed-off-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org Reviewed-by: Jeffrey Hugo quic_jhugo@quicinc.com Link: https://lore.kernel.org/r/20221228161704.255268-6-manivannan.sadhasivam@lina... Signed-off-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/bus/mhi/ep/main.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)
--- 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 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) {