On 04/04/2017 10:04 PM, Andrea Arcangeli wrote:
Hello Alexey, v3 looks great to me. Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> On top of v3 I think we could add this to make it more obvious to the developer tpid isn't necessarily there by just looking at the data structure. This is purely cosmetical, so feel free to comment if you disagree.
Why not, I agree with this change.
I'm also fine to add an anonymous union later if a new usage for those bytes emerges (ABI side doesn't change anything which is why this could be done later as well, only the API changes here but then I doubt we'd break the API later for this, so if we want pagefault.feat.* it probably should be done right now). Thanks, Andrea >From 901951f5a0456aa07d4fb1231cf2b1d352beb36f Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli <aarcange@xxxxxxxxxx> Date: Tue, 4 Apr 2017 20:50:54 +0200 Subject: [PATCH 1/1] userfaultfd: provide pid in userfault msg - add feat union No ABI change, but this will make it more explicit to software that ptid is only available if requested by passing UFFD_FEATURE_THREAD_ID to UFFDIO_API. The fact it's a union will also self document it shouldn't be taken for granted there's a tpid there. Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> --- include/uapi/linux/userfaultfd.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h index ff8d0d2..524b860 100644 --- a/include/uapi/linux/userfaultfd.h +++ b/include/uapi/linux/userfaultfd.h @@ -84,7 +84,9 @@ struct uffd_msg { struct { __u64 flags; __u64 address; - __u32 ptid; + union { + __u32 ptid; + } feat; } pagefault;struct {
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