There is a race condition where mhi_prepare_channel() updates the
read and write pointers as the base address and in parallel, if
an M0 transition occurs, the tasklet goes ahead and rings
doorbells for all channels with a delta in TRE rings assuming
they are already enabled. This causes a null pointer access. Fix
it by adding a channel enabled check before ringing channel
doorbells.
Signed-off-by: Qiang Yu <[email protected]>
---
drivers/bus/mhi/host/pm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c
index 4a42186..0834590 100644
--- a/drivers/bus/mhi/host/pm.c
+++ b/drivers/bus/mhi/host/pm.c
@@ -301,7 +301,8 @@ int mhi_pm_m0_transition(struct mhi_controller *mhi_cntrl)
read_lock_irq(&mhi_chan->lock);
/* Only ring DB if ring is not empty */
- if (tre_ring->base && tre_ring->wp != tre_ring->rp)
+ if (tre_ring->base && tre_ring->wp != tre_ring->rp &&
+ mhi_chan->ch_state == MHI_CH_STATE_ENABLED)
mhi_ring_chan_db(mhi_cntrl, mhi_chan);
read_unlock_irq(&mhi_chan->lock);
}
--
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