Messages in this thread | | | Date | Tue, 7 Nov 2023 15:19:02 +0800 | Subject | Re: [PATCH v2 1/2] bus: mhi: host: Add spinlock to protect WP access when queueing TREs | From | Qiang Yu <> |
| |
On 11/6/2023 12:41 PM, Manivannan Sadhasivam wrote: > On Wed, Sep 13, 2023 at 04:47:40PM +0800, Qiang Yu wrote: >> From: Bhaumik Bhatt <bbhatt@codeaurora.org> >> >> Protect WP accesses such that multiple threads queueing buffers for >> incoming data do not race and access the same WP twice. 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. >> > This change is doing two things: > > 1. Unlocking xfer_cb to prevent potential lockup > 2. Protecting mhi_gen_tre() against concurrent access > > So you should split this into two patches and also add Fixes tag if appropriate. > > - Mani Hi Mani, thanks for review. I split this into two patch and add Fixes tag. > >> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org> >> Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com> >> --- >> drivers/bus/mhi/host/main.c | 11 ++++++++++- >> 1 file changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c >> index dcf627b..13c4b89 100644 >> --- a/drivers/bus/mhi/host/main.c >> +++ b/drivers/bus/mhi/host/main.c >> @@ -642,6 +642,7 @@ 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); >> >> @@ -667,6 +668,7 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl, >> kfree(buf_info->cb_buf); >> } >> } >> + read_lock_bh(&mhi_chan->lock); >> } >> break; >> } /* CC_EOT */ >> @@ -1204,6 +1206,9 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan, >> int eot, eob, chain, bei; >> int ret; >> >> + /* Protect accesses for reading and incrementing WP */ >> + write_lock_bh(&mhi_chan->lock); >> + >> buf_ring = &mhi_chan->buf_ring; >> tre_ring = &mhi_chan->tre_ring; >> >> @@ -1221,8 +1226,10 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan, >> >> if (!info->pre_mapped) { >> ret = mhi_cntrl->map_single(mhi_cntrl, buf_info); >> - if (ret) >> + if (ret) { >> + write_unlock_bh(&mhi_chan->lock); >> return ret; >> + } >> } >> >> eob = !!(flags & MHI_EOB); >> @@ -1239,6 +1246,8 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan, >> mhi_add_ring_element(mhi_cntrl, tre_ring); >> mhi_add_ring_element(mhi_cntrl, buf_ring); >> >> + write_unlock_bh(&mhi_chan->lock); >> + >> return 0; >> } >> >> -- >> 2.7.4 >> >>
| |