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SubjectRe: [PATCH v4 4/4] bus: mhi: host: Take irqsave lock after TRE is generated
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On 12/7/2023 2:38 PM, Manivannan Sadhasivam wrote:
> On Mon, Nov 27, 2023 at 03:19:49PM +0800, Qiang Yu wrote:
>> On 11/24/2023 6:09 PM, Manivannan Sadhasivam wrote:
>>> On Tue, Nov 14, 2023 at 01:27:41PM +0800, Qiang Yu wrote:
>>>> From: Hemant Kumar <quic_hemantk@quicinc.com>
>>>>
>>>> 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
>>> "__local_bh_enable_ip" is a function name, so you should not break it.
>> Thanks for let me know, will note this in following patch.
>>>> lock after TRE is generated to avoid running write_unlock_bh when irqsave
>>>> lock is held.
>>>>
>>> I still don't understand this commit message. Where is the write_unlock_bh()
>>> being called?
>>>
>>> - Mani
>> Write_unlock_bh() is invoked in mhi_gen_te()
>> The calling flow is like
>> mhi_queue
>>     read_lock_irqsave(&mhi_cntrl->pm_lock, flags)
>>     mhi_gen_tre
>>         write_lock_bh(&mhi_chan->lock)
>>         write_unlock_bh(&mhi_chan->lock)   // Will enable irq if
>> CONFIG_TRACE_IRQFLAGS is enabled
>>     read_lock_irqsave(&mhi_cntrl->pm_lock, flags)
>>
>> after adding this patch, the calling flow becomes
>>
>> mhi_queue
>>     mhi_gen_tre
>>         write_lock_bh(&mhi_chan->lock)
>>         write_unlock_bh(&mhi_chan->lock)
>>     read_lock_irqsave(&mhi_cntrl->pm_lock, flags)
>>     read_lock_irqsave(&mhi_cntrl->pm_lock, flags)
> So this patch essentially fixes the issue caused by patch 1? If so, this should
> be squashed into patch 1.
>
> - Mani

Yes, this patch is to fix the issue caused by patch 1. Will squash patch
1 and this patch into one patch

in next version.

>
>>>> 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 33f27e2..d7abd0b 100644
>>>> --- a/drivers/bus/mhi/host/main.c
>>>> +++ b/drivers/bus/mhi/host/main.c
>>>> @@ -1128,17 +1128,15 @@ 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
>>>> @@ -1158,7 +1156,6 @@ 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
>>>>
>>>>

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