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@xxxxxxxxxxxxxx>
> ---
>
> 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.
Thanks,
Mani
> + if (cur_state == MHI_PM_DISABLE) {
> + mutex_unlock(&mhi_cntrl->pm_mutex);
> + return; /* Already powered down */
> + }
> +
> /* If it's not a graceful shutdown, force MHI to linkdown state */
> transition_state = (graceful) ? MHI_PM_SHUTDOWN_PROCESS :
> MHI_PM_LD_ERR_FATAL_DETECT;
>
> - mutex_lock(&mhi_cntrl->pm_mutex);
> write_lock_irq(&mhi_cntrl->pm_lock);
> cur_state = mhi_tryset_pm_state(mhi_cntrl, transition_state);
> if (cur_state != transition_state) {
> --
> Qualcomm Technologies, Inc. is a member of the
> Code Aurora Forum, a Linux Foundation Collaborative Project.
>
