Re: [bug report] bus: mhi: core: Add support for data transfer

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

Hi Dan,

On Tue, Apr 07, 2020 at 04:55:59PM +0300, Dan Carpenter wrote:
> Hello Manivannan Sadhasivam,
> 
> The patch 189ff97cca53: "bus: mhi: core: Add support for data
> transfer" from Feb 20, 2020, leads to the following static checker
> warning:
> 
> 	drivers/bus/mhi/core/main.c:1153 mhi_queue_buf()
> 	error: double locked 'mhi_chan->lock' (orig line 1110)
> 
> drivers/bus/mhi/core/main.c
>   1142          }
>   1143  
>   1144          /* Toggle wake to exit out of M2 */
>   1145          mhi_cntrl->wake_toggle(mhi_cntrl);
>   1146  
>   1147          if (mhi_chan->dir == DMA_TO_DEVICE)
>   1148                  atomic_inc(&mhi_cntrl->pending_pkts);
>   1149  
>   1150          if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl))) {
>   1151                  unsigned long flags;
>   1152  
>   1153                  read_lock_irqsave(&mhi_chan->lock, flags);
>                                           ^^^^^^^^^^^^^^^
> The caller is already holding this lock.
> 

Hmm. We have one internal user of this function and that's where the locking
has gone wrong. Will fix it.

Thanks for reporting!

Regards,
Mani

>   1154                  mhi_ring_chan_db(mhi_cntrl, mhi_chan);
>   1155                  read_unlock_irqrestore(&mhi_chan->lock, flags);
>   1156          }
>   1157  
>   1158          read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);
>   1159  
>   1160          return 0;
>   1161  }
>   1162  EXPORT_SYMBOL_GPL(mhi_queue_buf);
> 
> regards,
> dan carpenter