bus: mhi: host: Fix race between channel preparation and M0 event

stable inclusion
from stable-v5.10.164
commit ab9bb65b851973fd7843f83830e4ed518d9e213b
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7T7G4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ab9bb65b851973fd7843f83830e4ed518d9e213b



--------------------------------

[ Upstream commit 869a9990 ]

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.

Cc: stable@vger.kernel.org # 5.19
Fixes: a6e2e352 "bus: mhi: core: Add support for PM state transitions"
Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Link: https://lore.kernel.org/r/1665889532-13634-1-git-send-email-quic_qianyu@quicinc.com


[mani: CCed stable list]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>