Commit 3bc1a5f4 authored by Hemant Kumar's avatar Hemant Kumar Committed by Greg Kroah-Hartman

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: default avatarHemant Kumar <hemantk@codeaurora.org>
Reviewed-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20200521170249.21795-14-manivannan.sadhasivam@linaro.orgSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 30b78924
......@@ -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;
if (mhi_chan->db_cfg.reset_req) {
write_lock_irq(&mhi_chan->lock);
if (mhi_chan->db_cfg.reset_req)
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);
......
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