Hi !
A probably very basic sparse question - but I could not figure out a
satisfying answer. while compile testing a patch for ntb_transfer.c I got
CHECK drivers/ntb/ntb_transport.c
drivers/ntb/ntb_transport.c:1583:43: warning: incorrect type in argument 1 (different address spaces)
drivers/ntb/ntb_transport.c:1583:43: expected void *dst
drivers/ntb/ntb_transport.c:1583:43: got void [noderef] <asn:2>*offset
drivers/ntb/ntb_transport.c:1583:56: warning: incorrect type in argument 2 (different address spaces)
drivers/ntb/ntb_transport.c:1583:56: expected void const [noderef] <asn:1>*src
drivers/ntb/ntb_transport.c:1583:56: got void *buf
looking at the offending line;
static void ntb_memcpy_tx(struct ntb_queue_entry *entry, void __iomem *offset)
{
#ifdef ARCH_HAS_NOCACHE_UACCESS
/*
* Using non-temporal mov to improve performance on non-cached
* writes, even though we aren't actually copying from user space.
*/
__copy_from_user_inatomic_nocache(offset, entry->buf, entry->len);
the absence of a __user in the buf argument seems intentional and the
dst is not a kernel but __iomem address which triggers the second warning
So the first warning seems to be a false positive here, the second one
Im not clear about, but I guess its also a false positive. The question
is if there is a clean way to anotate this to make sparse happy without
any unwanted sideffects ?
For the first warning using (void __user *) entry->buf should do
and be side-effect free, but how could the second warning be fixed ?
sparse message is from 4.8.0-rc2 (localversion-next is -next-20160822)
sparse version is v0.5.0-44
thx!
hofrat
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