From: Hemant Kumar Date: Thu, 21 May 2020 17:02:48 +0000 (+0530) Subject: bus: mhi: core: Handle write lock properly in mhi_pm_m0_transition X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3bc1a5f431618a656bbf674a4627ef4da3a0d893;p=linux.git 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 --- diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c index 345f197130b8a..de5abb26bcae1 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);