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[BUG] ntb: Sleep in interrupt handling

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  [BUG] ntb: Sleep in interrupt handling Jia-Ju Bai <baijiaju1990@163.com> - 2017-06-01 11:20 +0200
    RE: [BUG] ntb: Sleep in interrupt handling "Allen Hubbe" <Allen.Hubbe@dell.com> - 2017-06-01 15:20 +0200

#1654956 — [BUG] ntb: Sleep in interrupt handling

According to ntb_transport.c, the driver may sleep in interrupt handling.
The function call path is:
ntb_transport_rxc_db (tasklet_init indicates it handles interrupt)
   ntb_process_rxc
     ntb_async_rx
       ntb_async_rx_submit
         schedule_timeout --> may sleep

This bug is found by my static analysis tool and my code review.
I hope to fix it, but I do not have a good solution.

Thanks,
Jia-Ju Bai

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#1655129

From: Jia-Ju Bai 
> According to ntb_transport.c, the driver may sleep in interrupt handling.
> The function call path is:
> ntb_transport_rxc_db (tasklet_init indicates it handles interrupt)
>    ntb_process_rxc
>      ntb_async_rx
>        ntb_async_rx_submit
>          schedule_timeout --> may sleep
> 
> This bug is found by my static analysis tool and my code review.
> I hope to fix it, but I do not have a good solution.

Thanks! There is a recovery path if ntb_async_tx_submit fails.  It will do the transmission with memcpy instead of dma.  So, rather than retry in ntb_async_tx_submit, just fail to the recovery path.  Basically, replace the whole for(retries) loop with just txd = prep();  Would you like to work on the patch?

> 
> Thanks,
> Jia-Ju Bai

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