Re: [PATCH] mtd: gpmi: Fix NULL pointer dereference

[Huang Shijie <b32955@freescale.com>]

于 2013年11月12日 02:23, Brian Norris 写道:
> (2) The second switched the whole NAND buffer over to a kzalloc'd
>     buffer, with NAND_OWN_BUFFERS. I'm not a huge fan of
>     NAND_OWN_BUFFERS, and I think drivers should only be using it if
>     they really need it, for special buffer placement or some other good
>     reason. You just happen to need a buffer "too early", where you can
>     really just allocate a small temporary buffer.
why I use the NAND_OWN_BUFFERS? just for a small temporary buffer?
the answer is no.

For imx23, the work flow is like this:
[1] first check the fingerprint, if we can find it, we will return
immediately.
[2] if [1] failed, such as you erase all the partitions, the gpmi will call
mx23_write_transcription_stamp() to write the fingerprint.

So the @chip->buffer is not only used by the
mx23_check_transcription_stamp(),
but _also_ used by the mx23_write_transcription_stamp() when the gpmi
can not find any
fingerprint in the NAND page.


That's why i use the NAND_OWN_BUFFERS, the buffer can be used by both
the mx23_check_transcription_stamp()
and mx23_write_transcription_stamp().

thanks
Huang Shijie