Re: [PATCH] IB/core: avoid 32-bit warning

[Yann Droneaud]

Hi,

Le mercredi 07 octobre 2015 Ã 16:19 +0300, Sagi Grimberg a Ãcrit :
> On 10/7/2015 3:29 PM, Arnd Bergmann wrote:
> > The INIT_UDATA() macro requires a pointer or unsigned long argument
> > for
> > both input and output buffer, and all callers had a cast from when
> > the code was merged until a recent restructuring, so now we get
> > 
> > core/uverbs_cmd.c: In function 'ib_uverbs_create_cq':
> > core/uverbs_cmd.c:1481:66: warning: cast to pointer from integer of
> > different size [-Wint-to-pointer-cast]
> > 
> > This makes the code behave as before by adding back the cast to
> > unsigned long.
> > 
> > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> > Fixes: 565197dd8fb1 ("IB/core: Extend ib_uverbs_create_cq")
> > 
> > diff --git a/drivers/infiniband/core/uverbs_cmd.c
> > b/drivers/infiniband/core/uverbs_cmd.c
> > index be4cb9f04be3..88b3b78340f2 100644
> > --- a/drivers/infiniband/core/uverbs_cmd.c
> > +++ b/drivers/infiniband/core/uverbs_cmd.c
> > @@ -1478,7 +1478,7 @@ ssize_t ib_uverbs_create_cq(struct
> > ib_uverbs_file *file,
> >   	if (copy_from_user(&cmd, buf, sizeof(cmd)))
> >   		return -EFAULT;
> > 
> > -	INIT_UDATA(&ucore, buf, cmd.response, sizeof(cmd),
> > sizeof(resp));
> > +	INIT_UDATA(&ucore, buf, (unsigned long)cmd.response,
> > sizeof(cmd), sizeof(resp));
> 
> Would it make sense to cast inside INIT_UDATA() and not have callers
> worry about it?

It's ... complicated. See INIT_UDATA_BUF_OR_NULL().

Awayway, I have patch to do the opposite, eg. explicitly cast u64 value
to (void __user *)(unsigned long) in the caller function instead, as it
allows some safer / new operations on the response buffer.

Regards.

-- 
Yann Droneaud
OPTEYA

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