From: Hemant Kumar <quic_hemantk@quicinc.com>

Take irqsave lock after TRE is generated to avoid deadlock due to core
getting interrupts enabled as local_bh_enable must not be called with
irqs disabled based on upstream patch.

Signed-off-by: Hemant Kumar <quic_hemantk@quicinc.com>
Signed-off-by: Lazarus Motha <quic_lmotha@quicinc.com>
Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
---
 drivers/bus/mhi/host/main.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index b137d54..93b5110 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -1129,17 +1129,15 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
 	if (unlikely(MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)))
 		return -EIO;
 
-	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);
-
 	ret = mhi_is_ring_full(mhi_cntrl, tre_ring);
-	if (unlikely(ret)) {
-		ret = -EAGAIN;
-		goto exit_unlock;
-	}
+	if (unlikely(ret))
+		return -EAGAIN;
 
 	ret = mhi_gen_tre(mhi_cntrl, mhi_chan, buf_info, mflags);
 	if (unlikely(ret))
-		goto exit_unlock;
+		return ret;
+
+	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);
 
 	/* Packet is queued, take a usage ref to exit M3 if necessary
 	 * for host->device buffer, balanced put is done on buffer completion
@@ -1159,7 +1157,6 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
 	if (dir == DMA_FROM_DEVICE)
 		mhi_cntrl->runtime_put(mhi_cntrl);
 
-exit_unlock:
 	read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);
 
 	return ret;
-- 
2.7.4

On Tue, Nov 07, 2023 at 03:16:05PM +0800, Qiang Yu wrote:
> From: Hemant Kumar <quic_hemantk@quicinc.com>
> 
> Take irqsave lock after TRE is generated to avoid deadlock due to core
> getting interrupts enabled as local_bh_enable must not be called with
> irqs disabled based on upstream patch.
> 

You still didn't address any of the comments provided by Jeff in v2.

- Mani

> Signed-off-by: Hemant Kumar <quic_hemantk@quicinc.com>
> Signed-off-by: Lazarus Motha <quic_lmotha@quicinc.com>
> Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
> ---
>  drivers/bus/mhi/host/main.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> index b137d54..93b5110 100644
> --- a/drivers/bus/mhi/host/main.c
> +++ b/drivers/bus/mhi/host/main.c
> @@ -1129,17 +1129,15 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
>  	if (unlikely(MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)))
>  		return -EIO;
>  
> -	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);
> -
>  	ret = mhi_is_ring_full(mhi_cntrl, tre_ring);
> -	if (unlikely(ret)) {
> -		ret = -EAGAIN;
> -		goto exit_unlock;
> -	}
> +	if (unlikely(ret))
> +		return -EAGAIN;
>  
>  	ret = mhi_gen_tre(mhi_cntrl, mhi_chan, buf_info, mflags);
>  	if (unlikely(ret))
> -		goto exit_unlock;
> +		return ret;
> +
> +	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);
>  
>  	/* Packet is queued, take a usage ref to exit M3 if necessary
>  	 * for host->device buffer, balanced put is done on buffer completion
> @@ -1159,7 +1157,6 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
>  	if (dir == DMA_FROM_DEVICE)
>  		mhi_cntrl->runtime_put(mhi_cntrl);
>  
> -exit_unlock:
>  	read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);
>  
>  	return ret;
> -- 
> 2.7.4
> 
> 

-- 
மணிவண்ணன் சதாசிவம்

On 11/10/2023 12:29 AM, Manivannan Sadhasivam wrote:
> On Tue, Nov 07, 2023 at 03:16:05PM +0800, Qiang Yu wrote:
>> From: Hemant Kumar <quic_hemantk@quicinc.com>
>>
>> Take irqsave lock after TRE is generated to avoid deadlock due to core
>> getting interrupts enabled as local_bh_enable must not be called with
>> irqs disabled based on upstream patch.
>>
> You still didn't address any of the comments provided by Jeff in v2.
>
> - Mani

Hi Mani, thanks for review. Sorry, missing this part. Will change to 
following commit message.

If CONFIG_TRACE_IRQFLAGS is enabled, irq will be enabled once 
__local_bh_enable_ip
is called as part of write_unlock_bh. Hence, let's take irqsave lock 
after TRE is
generated to avoid running write_unlock_bh when irqsave lock is held.

>> Signed-off-by: Hemant Kumar <quic_hemantk@quicinc.com>
>> Signed-off-by: Lazarus Motha <quic_lmotha@quicinc.com>
>> Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
>> ---
>>   drivers/bus/mhi/host/main.c | 13 +++++--------
>>   1 file changed, 5 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
>> index b137d54..93b5110 100644
>> --- a/drivers/bus/mhi/host/main.c
>> +++ b/drivers/bus/mhi/host/main.c
>> @@ -1129,17 +1129,15 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
>>   	if (unlikely(MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)))
>>   		return -EIO;
>>   
>> -	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);
>> -
>>   	ret = mhi_is_ring_full(mhi_cntrl, tre_ring);
>> -	if (unlikely(ret)) {
>> -		ret = -EAGAIN;
>> -		goto exit_unlock;
>> -	}
>> +	if (unlikely(ret))
>> +		return -EAGAIN;
>>   
>>   	ret = mhi_gen_tre(mhi_cntrl, mhi_chan, buf_info, mflags);
>>   	if (unlikely(ret))
>> -		goto exit_unlock;
>> +		return ret;
>> +
>> +	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);
>>   
>>   	/* Packet is queued, take a usage ref to exit M3 if necessary
>>   	 * for host->device buffer, balanced put is done on buffer completion
>> @@ -1159,7 +1157,6 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
>>   	if (dir == DMA_FROM_DEVICE)
>>   		mhi_cntrl->runtime_put(mhi_cntrl);
>>   
>> -exit_unlock:
>>   	read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);
>>   
>>   	return ret;
>> -- 
>> 2.7.4
>>
>>