Re: [PATCH v2] i2c: bcm2835: Clear current buffer pointers and counts after a transfer

[Wolfram Sang <wsa@the-dreams.de>]

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On Thu, Dec 27, 2018 at 04:42:25PM +0100, Paul Kocialkowski wrote:
> The driver's interrupt handler checks whether a message is currently
> being handled with the curr_msg pointer. When it is NULL, the interrupt
> is considered to be unexpected. Similarly, the i2c_start_transfer
> routine checks for the remaining number of messages to handle in
> num_msgs.
> 
> However, these values are never cleared and always keep the message and
> number relevant to the latest transfer (which might be done already and
> the underlying message memory might have been freed).
> 
> When an unexpected interrupt hits with the DONE bit set, the isr will
> then try to access the flags field of the curr_msg structure, leading
> to a fatal page fault.
> 
> The msg_buf and msg_buf_remaining fields are also never cleared at the
> end of the transfer, which can lead to similar pitfalls.
> 
> Fix these issues by introducing a cleanup function and always calling
> it after a transfer is finished.
> 
> Fixes: e2474541032d ("i2c: bcm2835: Fix hang for writing messages larger than 16 bytes")
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>

Stefan, Florian, any comment about this patch?


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