On Fri, Apr 16, 2021 at 03:05:31PM +0530, Aneesh Kumar K.V wrote:
> On 4/16/21 2:39 PM, Andy Shevchenko wrote:
> > On Fri, Apr 16, 2021 at 01:28:21PM +0530, Aneesh Kumar K.V wrote:
> > > On 4/15/21 7:16 PM, Andy Shevchenko wrote:
> > > > Parse to and export from UUID own type, before dereferencing.
> > > > This also fixes wrong comment (Little Endian UUID is something else)
> > > > and should fix Sparse warnings about assigning strict types to POD.
> > > >
> > > > Fixes: 43001c52b603 ("powerpc/papr_scm: Use ibm,unit-guid as the iset
> > > > cookie")
> > > > Fixes: 259a948c4ba1 ("powerpc/pseries/scm: Use a specific endian format
> > > > for storing uuid from the device tree")
> > > > Cc: Oliver O'Halloran <ooh...@gmail.com>
> > > > Cc: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
> > > > Signed-off-by: Andy Shevchenko <andriy.shevche...@linux.intel.com>
> > > > ---
> > > > Not tested
> > > > arch/powerpc/platforms/pseries/papr_scm.c | 13 ++++++++-----
> > > > 1 file changed, 8 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/arch/powerpc/platforms/pseries/papr_scm.c
> > > > b/arch/powerpc/platforms/pseries/papr_scm.c
> > > > index ae6f5d80d5ce..4366e1902890 100644
> > > > --- a/arch/powerpc/platforms/pseries/papr_scm.c
> > > > +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> > > > @@ -1085,8 +1085,9 @@ static int papr_scm_probe(struct platform_device
> > > > *pdev)
> > > > u32 drc_index, metadata_size;
> > > > u64 blocks, block_size;
> > > > struct papr_scm_priv *p;
> > > > + u8 uuid_raw[UUID_SIZE];
> > > > const char *uuid_str;
> > > > - u64 uuid[2];
> > > > + uuid_t uuid;
> > > > int rc;
> > > > /* check we have all the required DT properties */
> > > > @@ -1129,16 +1130,18 @@ static int papr_scm_probe(struct
> > > > platform_device *pdev)
> > > > p->hcall_flush_required = of_property_read_bool(dn,
> > > > "ibm,hcall-flush-required");
> > > > /* We just need to ensure that set cookies are unique across */
> > > > - uuid_parse(uuid_str, (uuid_t *) uuid);
> > > > + uuid_parse(uuid_str, &uuid);
> > > > +
> > > > /*
> > > > * cookie1 and cookie2 are not really little endian
> > > > - * we store a little endian representation of the
> > > > + * we store a raw buffer representation of the
> > > > * uuid str so that we can compare this with the label
> > > > * area cookie irrespective of the endian config with which
> > > > * the kernel is built.
> > > > */
> > > > - p->nd_set.cookie1 = cpu_to_le64(uuid[0]);
> > > > - p->nd_set.cookie2 = cpu_to_le64(uuid[1]);
> > > > + export_uuid(uuid_raw, &uuid);
> > > > + p->nd_set.cookie1 = get_unaligned_le64(&uuid_raw[0]);
> > > > + p->nd_set.cookie2 = get_unaligned_le64(&uuid_raw[8]);
> > >
> > > ok that does the equivalent of cpu_to_le64 there. So we are good. But the
> > > comment update is missing the details why we did that get_unaligned_le64.
> > > Maybe raw buffer representation is the correct term?
> > > Should we add an example in the comment. ie,
> >
> > > /*
> > > * Historically we stored the cookie in the below format.
> > > for a uuid str 72511b67-0b3b-42fd-8d1d-5be3cae8bcaa
> > > cookie1 was 0xfd423b0b671b5172 cookie2 was 0xaabce8cae35b1d8d
> > > */
> >
> > I'm fine with the comment. At least it will shed a light on the byte
> > ordering
> > we are expecting.
> >
>
> Will you be sending an update? Also it will be good to list the sparse
> warning in the commit message?
I'll send an update but I rephrase to remove mention of Sparse. I have no
Sparse build for this architecture.
If you have one, try to build with `make W=1 C=1 CF=-D__CHECK_ENDIAN__ ...`
which will enable warnings about restricted types assignment.
--
With Best Regards,
Andy Shevchenko
