[U-Boot] [PATCH] sf: Correct data types in stm_is_locked_sr()

[Albert ARIBAUD]

Hello Jagan,

On Sat, 12 Mar 2016 00:41:25 +0530, Jagan Teki
<jagannadh.teki at gmail.com> wrote:
> Hi Albert,
> 
> On 12 March 2016 at 00:17, Albert ARIBAUD <albert.u.boot at aribaud.net> wrote:
> > Hello Jagan,
> >
> > On Fri, 11 Mar 2016 12:09:37 +0530, Jagan Teki
> > <jagannadh.teki at gmail.com> wrote:
> >> On 11 March 2016 at 07:50, Marek Vasut <marex at denx.de> wrote:
> >> > The stm_is_locked_sr() function is picked from Linux kernel. For reason
> >> > unknown, the 64bit data types used by the function and present in Linux
> >> > were replaced with 32bit unsigned ones, which causes trouble.
> >> >
> >> > The testcase performed was done using ST M25P80 chip.
> >> > The command used was:
> >> >  => sf protect unlock 0 0x10000
> >> >
> >> > The call chain starts in stm_unlock(), which calls stm_is_locked_sr()
> >> > with negative ofs argument. This works fine in Linux, where the "ofs"
> >> > is loff_t, which is signed long long, while this fails in U-Boot, where
> >> > "ofs" is u32 (unsigned int). Because of this signedness problem, the
> >> > expression past the return statement to be incorrectly evaluated to 1,
> >> > which in turn propagates back to stm_unlock() and results in -EINVAL.
> >> >
> >> > The correction is very simple, just use the correctly sized data types
> >> > with correct signedness in the function to make it work as intended.
> >> >
> >> > Signed-off-by: Marek Vasut <marex at denx.de>
> >> > Cc: Simon Glass <sjg at chromium.org>
> >> > Cc: Jagan Teki <jteki at openedev.com>
> >> > ---
> >> >  drivers/mtd/spi/spi_flash.c | 6 +++---
> >> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >> >
> >> > diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
> >> > index 2ae2e3c..44d9e9b 100644
> >> > --- a/drivers/mtd/spi/spi_flash.c
> >> > +++ b/drivers/mtd/spi/spi_flash.c
> >> > @@ -665,7 +665,7 @@ int sst_write_bp(struct spi_flash *flash, u32 offset, size_t len,
> >> >
> >> >  #if defined(CONFIG_SPI_FLASH_STMICRO) || defined(CONFIG_SPI_FLASH_SST)
> >> >  static void stm_get_locked_range(struct spi_flash *flash, u8 sr, loff_t *ofs,
> >> > -                                u32 *len)
> >> > +                                u64 *len)
> >>
> >> What about uint64_t?
> >
> > Well, the U-Boot coding style [1] suggest that we follow the Linux
> > coding style [2] which itself suggests [chapter 5, item (d)] that when
> 
> uNN types means uint32_t/uint64_t ?

No, uNN means u8/u16/u32, but I'll admit that may not have been totally
unambiguous.

> > uNN types are being used already in some code, then changes to this
> > code should keep on using uNN types.
> 
> Sorry, I didn't understand here - if the code having these uNN types
> the changes to same uNN types?

It was better explained in the URL I gave. :)

Basically: the Linux (and therefore U-Boot) coding style guide says if
some code uses u8/u16/u32, then changes to this code should keep using
u8/u16/u32; and here, drivers/mtd/spi/spi_flash.c uses u8, u16 and u32
so the wrongly-sized u32 should be changed into a u64, not into a
uint64_t.

> thanks!
> -- 
> Jagan.

Amicalement,
-- 
Albert.