Messages in this thread | | | Subject | Re: [PATCH v2] bus: mhi: core: Check state before processing power_down | From | Jeffrey Hugo <> | Date | Wed, 24 Feb 2021 08:14:53 -0700 |
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On 2/24/2021 2:55 AM, Manivannan Sadhasivam wrote: > On Wed, Feb 17, 2021 at 09:43:31AM -0700, Jeffrey Hugo wrote: >> We cannot process a power_down if the power state is DISABLED. There is >> no valid mhi_ctxt in that case, so attepting to process the power_down >> will likely result in a null pointer dereference. If the power state is >> DISABLED, there is nothing to do anyways, so just bail early. >> >> Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org> >> --- >> >> v2: Fix subject and tweak the locking to avoid needless lock/unlock/relock >> >> drivers/bus/mhi/core/pm.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c >> index 56ba3ab..47f6621 100644 >> --- a/drivers/bus/mhi/core/pm.c >> +++ b/drivers/bus/mhi/core/pm.c >> @@ -1144,6 +1144,7 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl) >> mhi_deinit_dev_ctxt(mhi_cntrl); >> >> error_dev_ctxt: >> + mhi_cntrl->pm_state = MHI_PM_DISABLE; >> mutex_unlock(&mhi_cntrl->pm_mutex); >> >> return ret; >> @@ -1155,11 +1156,17 @@ void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful) >> enum mhi_pm_state cur_state, transition_state; >> struct device *dev = &mhi_cntrl->mhi_dev->dev; >> >> + mutex_lock(&mhi_cntrl->pm_mutex); >> + cur_state = mhi_cntrl->pm_state; > > As I said in my previous review, you should use pm_lock for reading the > pm_state.
You also said on IRC that is a refactor of the entire driver, and not a blocker for this fix. Based on that, I intrepreted your comments as nothing needed to be done regarding the locking, so I'm confused by this comment.
I'm not entirely sure what you want since I feel like you are giving conflicting direction, but I'm guessing you want the lock of the pm_lock to be moved up to just under the mutex lock then?
-- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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