On Tue, 2015-06-09 at 09:18 -0500, Steve Wise wrote: > > > > > Why are you using a cast here at all? bar2_pa is already u64... > > > > > > > > > > So it should just have the (uintptr_t) cast? > > > > No, it should be no cast at all. The uintptr_t cast is only for casting > > an int->ptr or ptr->int. In those cases, if the size of an int != size > > of ptr, you can loose data, and uintptr_t tells the compiler "I know I'm > > casting between possibly lossy data sizes and either A) I've checked and > > it's OK or B) I'm ok with ptr truncation and the loss won't hurt us". > > It basically turns off size checks when sticking a ptr into an int. You > > should therefore use it only in those circumstances. For example, when > > storing a cookie that doesn't have a strict uniqueness requirement, the > > loss due to truncation is probably OK. Or if you know you are only > > doing something like initially storing an int into a pointer, and then > > later storing that pointer back into an int, so there can never be any > > truncation because the source of the ptr was always int sized. Those > > are the times to use uintptr. In this case, you have a real u64 going > > into a real u64, there should be no casts. > > > > My bad. I thought bar2_pa was a ptr...
I didn't look up the actual structure definition, but:
+ cq->bar2_va = c4iw_bar2_addrs(rdev, cq->cqid, T4_BAR2_QTYPE_INGRESS,
+ &cq->bar2_qid,
+ user ? &cq->bar2_pa : NULL);
+void __iomem *c4iw_bar2_addrs(struct c4iw_rdev *rdev, unsigned int qid,
+ enum cxgb4_bar2_qtype qtype,
+ unsigned int *pbar2_qid, u64 *pbar2_pa)
Looks like either it's a u64 or else there should be compiler warnings
about passing &cq->bar2_pa to c4iw_bar2_addrs.
--
Doug Ledford <dledf...@redhat.com>
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