* [PATCH v2] bus: mhi: core: Check state before processing power_down
@ 2021-02-17 16:43 Jeffrey Hugo
2021-02-24 9:55 ` Manivannan Sadhasivam
0 siblings, 1 reply; 4+ messages in thread
From: Jeffrey Hugo @ 2021-02-17 16:43 UTC (permalink / raw)
To: manivannan.sadhasivam, hemantk
Cc: bbhatt, linux-arm-msm, linux-kernel, Jeffrey Hugo
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;
+ 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.
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] bus: mhi: core: Check state before processing power_down
2021-02-17 16:43 [PATCH v2] bus: mhi: core: Check state before processing power_down Jeffrey Hugo
@ 2021-02-24 9:55 ` Manivannan Sadhasivam
2021-02-24 15:14 ` Jeffrey Hugo
0 siblings, 1 reply; 4+ messages in thread
From: Manivannan Sadhasivam @ 2021-02-24 9:55 UTC (permalink / raw)
To: Jeffrey Hugo; +Cc: hemantk, bbhatt, linux-arm-msm, linux-kernel
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.
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.
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] bus: mhi: core: Check state before processing power_down
2021-02-24 9:55 ` Manivannan Sadhasivam
@ 2021-02-24 15:14 ` Jeffrey Hugo
2021-02-24 15:58 ` Manivannan Sadhasivam
0 siblings, 1 reply; 4+ messages in thread
From: Jeffrey Hugo @ 2021-02-24 15:14 UTC (permalink / raw)
To: Manivannan Sadhasivam; +Cc: hemantk, bbhatt, linux-arm-msm, linux-kernel
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.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] bus: mhi: core: Check state before processing power_down
2021-02-24 15:14 ` Jeffrey Hugo
@ 2021-02-24 15:58 ` Manivannan Sadhasivam
0 siblings, 0 replies; 4+ messages in thread
From: Manivannan Sadhasivam @ 2021-02-24 15:58 UTC (permalink / raw)
To: Jeffrey Hugo; +Cc: hemantk, bbhatt, linux-arm-msm, linux-kernel
On Wed, Feb 24, 2021 at 08:14:53AM -0700, Jeffrey Hugo wrote:
> 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?
>
Yes, that's what my intention is. Sorry if I confused you.
Thanks,
Mani
> --
> Jeffrey Hugo
> Qualcomm Technologies, Inc. is a member of the
> Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-02-17 16:43 [PATCH v2] bus: mhi: core: Check state before processing power_down Jeffrey Hugo
2021-02-24 9:55 ` Manivannan Sadhasivam
2021-02-24 15:14 ` Jeffrey Hugo
2021-02-24 15:58 ` Manivannan Sadhasivam
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