Messages in this thread |  | | Date | Sun, 9 Apr 2017 09:33:23 +0200 | From | Boris Brezillon <> | Subject | Re: [PATCH v3 33/37] mtd: nand: allocate aligned buffers if NAND_OWN_BUFFERS is unset |
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On Fri, 7 Apr 2017 15:49:23 +0900 Masahiro Yamada <yamada.masahiro@socionext.com> wrote:
> Hi Leonard, > > 2017-04-06 23:08 GMT+09:00 Leonard Crestez <leonard.crestez@nxp.com>: > > On Thu, Mar 30, 2017 at 11:15 AM, Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > >> > >> Some NAND controllers are using DMA engine requiring a specific > >> buffer alignment. The core provides no guarantee on the nand_buffers > >> pointers, which forces some drivers to allocate their own buffers > >> and pass the NAND_OWN_BUFFERS flag. > >> > >> Rework the nand_buffers allocation logic to allocate each buffer > >> independently. This should make most NAND controllers/DMA engine > >> happy, and allow us to get rid of these custom buf allocation in > >> NAND controller drivers. > >> > >> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > > >> @@ -4914,8 +4930,12 @@ void nand_cleanup(struct nand_chip *chip) > >> > /* Free bad block table memory */ > >> kfree(chip->bbt); > >> - if (!(chip->options & NAND_OWN_BUFFERS)) > >> + if (!(chip->options & NAND_OWN_BUFFERS)) { > >> + kfree(chip->buffers->databuf); > >> + kfree(chip->buffers->ecccode); > >> + kfree(chip->buffers->ecccalc); > >> kfree(chip->buffers); > >> + } > > > > It seems that chip->buffers might not be allocated at this point, for > > example if nand_cleanup is called during a failed probe. You should > > check if (chip->buffers != NULL) before freeing stuff inside it. > > You are right. > > The failure path in NAND drivers is messy. :-(
Totally agree, and that's partly because of the complex/non-trivial NAND APIs :-/.
> nand_cleanup() may be called before nand_scan_tail() > finishes successfully...
Actually, I think the real bug is in the GPMI driver which is not using nand_release() appropriately. nand_release() is supposed to be called on a registered NAND device, so it's wrong to call it before mtd_register() has been called and returned 0.
Note that nand_cleanup() can only be called after nand_scan_tail() has returned 0 (which unfortunately is not obvious :-/).
I still plan to take Masahiro's fixup patch because the more precautions we take the better it is, but I still think the real bug is in the GPMI driver.
One last comment: a bug still exists in the GPMI driver when nand_scan_ident() fails after NAND buffers allocation because it never sets chip->buffers back to NULL (see [1]).
[1]http://lxr.free-electrons.com/source/drivers/mtd/nand/nand_base.c#L4834
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