diff mbox series

[13/14] bus: mhi: core: Handle write lock properly in mhi_pm_m0_transition

Message ID 20200521152540.17335-14-mani@kernel.org (mailing list archive)
State Accepted
Commit 3bc1a5f431618a656bbf674a4627ef4da3a0d893
Headers show
Series MHI patches for v5.8 | expand

Commit Message

Manivannan Sadhasivam May 21, 2020, 3:25 p.m. UTC 
From: Hemant Kumar <hemantk@codeaurora.org>

Take write lock only to protect db_mode member of mhi channel.
This allows rest of the mhi channels to just take read lock which
fine grains the locking. It prevents channel readers to starve if
they try to enter critical section after a writer.

Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/bus/mhi/core/pm.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index a5d9973059c8..e6236a3ca39d 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -288,14 +288,18 @@  int mhi_pm_m0_transition(struct mhi_controller *mhi_cntrl)
 	for (i = 0; i < mhi_cntrl->max_chan; i++, mhi_chan++) {
 		struct mhi_ring *tre_ring = &mhi_chan->tre_ring;
 
-		write_lock_irq(&mhi_chan->lock);
-		if (mhi_chan->db_cfg.reset_req)
+		if (mhi_chan->db_cfg.reset_req) {
+			write_lock_irq(&mhi_chan->lock);
 			mhi_chan->db_cfg.db_mode = true;
+			write_unlock_irq(&mhi_chan->lock);
+		}
+
+		read_lock_irq(&mhi_chan->lock);
 
 		/* Only ring DB if ring is not empty */
 		if (tre_ring->base && tre_ring->wp  != tre_ring->rp)
 			mhi_ring_chan_db(mhi_cntrl, mhi_chan);
-		write_unlock_irq(&mhi_chan->lock);
+		read_unlock_irq(&mhi_chan->lock);
 	}
 
 	mhi_cntrl->wake_put(mhi_cntrl, false);