From 3bc1a5f431618a656bbf674a4627ef4da3a0d893 Mon Sep 17 00:00:00 2001 From: Hemant Kumar Date: Thu, 21 May 2020 22:32:48 +0530 Subject: [PATCH] bus: mhi: core: Handle write lock properly in mhi_pm_m0_transition 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 Reviewed-by: Manivannan Sadhasivam Signed-off-by: Manivannan Sadhasivam Link: https://lore.kernel.org/r/20200521170249.21795-14-manivannan.sadhasivam@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/bus/mhi/core/pm.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c index 345f197130b8..de5abb26bcae 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); -- 2.39.5