Messages in this thread | | | Subject | Re: [PATCH] tty: serial: fsl_lpuart: fix del_timer_sync() vs timer routine deadlock | From | Bhuvanchandra DV <> | Date | Sat, 3 Dec 2016 15:36:56 +0530 |
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On 12/03/2016 02:25 PM, Nikita Yushchenko wrote:
> > 03.12.2016 10:06, Bhuvanchandra DV пишет: >> On 12/03/2016 02:58 AM, Nikita Yushchenko wrote: >> >>>>> Problem found via lockdep: >>>>> >>>>> - lpuart_set_termios() calls del_timer_sync(&sport->lpuart_timer) while >>>>> holding sport->port.lock >>>>> >>>>> - sport->lpuart_timer routine is lpuart_timer_func() that calls >>>>> lpuart_copy_rx_to_tty() that acquires same lock. >>>>> >>>>> To fix, move Rx DMA stopping out of lock, as it already is in other >>>>> places >>>>> in the same file. >>>>> >>>>> While at it, also make Rx DMA start/stop code to look the same is in >>>>> other places in the same file. >>>> Yeah I saw that too, never really came around to look closer into it. >>>> >>>> Thanks for looking into it. >>>> >>>> You removed the check whether there was an old configuration, I think >>>> the idea of that was that we only resize DMA if it was configured >>>> differently before... >>> Per my code reading, checking for sport->lpuart_dma_rx_use should be >>> enough, this flag will be set only if DMA was previously enabled, >> The check is to make sure the reconfiguration of DMA is done only when >> the baudrate is altered. > Then, ok to use > > if (old && sport->lpuart_dma_rx_use) {...} > > in both places?
Looks ok to me.
-- Bhuvan
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