David Howells
2018-Sep-06 09:18 UTC
[RFC] UAPI: Check headers by compiling all together as C++
Here's a set of patches that inserts a step into the build process to make
sure that the UAPI headers can all be built together with C++ (if the
compiler being used supports C++).
Note that it's based on a commit from the sound tree to fix usage of u32
and co..
Most of the patches perform fixups, including:
(1) Fix member names that conflict with C++ reserved words by providing
alternates that can be used anywhere. An anonymous union is used so
that that the conflicting name is still available outside of C++.
(2) Fix the use of flexible arrays in structs that get embedded (which is
illegal in C++).
(3) Remove the use of internal kernel structs in UAPI structures.
(4) Fix symbol collisions.
(5) Fix use of sparsely initialised arrays (which g++ doesn't implement).
(6) Remove some use of PAGE_SIZE since this isn't valid outside of the
kernel.
There's also:
(7) Move the coda_psdev.h header file to fs/coda/.
And lastly:
(8) Compile all of the UAPI headers (with a few exceptions) together as
C++ to catch new errors occurring as part of the regular build
process.
Changes for v2:
- Merge commit from sound tree to fix u32 usage issues
- Use a switch to fix sparse array initialisation
- Simplify nilfs2 by performing bitwise ops in LE space not CPU space
- Handle conflicting fix to use of 'private' in keyctl.h
- Move kernel internal coda bits to coda internal headers
- Move coda_psdev.h header to fs/coda/.
The patches can also be found here:
http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=uapi-check
Thanks,
David
---
David Howells (11):
UAPI: drm: Fix use of C++ keywords as structural members
UAPI: keys: Fix use of C++ keywords as structural members
UAPI: virtio_net: Fix use of C++ keywords as structural members
UAPI: bcache: Fix use of embedded flexible array
UAPI: coda: Move kernel internals out of public view
coda: Move internal defs out of include/linux/
UAPI: netfilter: Fix symbol collision issues
UAPI: nilfs2: Fix use of undefined byteswapping functions
UAPI: ndctl: Fix g++-unsupported initialisation in headers
UAPI: ndctl: Remove use of PAGE_SIZE
UAPI: Check headers build for C++
Makefile | 1
fs/coda/cache.c | 2
fs/coda/cnode.c | 2
fs/coda/coda_linux.c | 2
fs/coda/coda_psdev.h | 88 +++++++++++++++
fs/coda/dir.c | 2
fs/coda/file.c | 3 -
fs/coda/inode.c | 2
fs/coda/pioctl.c | 3 -
fs/coda/psdev.c | 3 -
fs/coda/symlink.c | 3 -
fs/coda/upcall.c | 2
include/linux/coda_psdev.h | 72 ------------
include/linux/ndctl.h | 22 ++++
include/uapi/drm/i810_drm.h | 7 +
include/uapi/drm/msm_drm.h | 7 +
include/uapi/linux/bcache.h | 2
include/uapi/linux/coda_psdev.h | 18 ---
include/uapi/linux/keyctl.h | 7 +
include/uapi/linux/ndctl.h | 52 ++++-----
include/uapi/linux/netfilter/nfnetlink_cthelper.h | 2
include/uapi/linux/netfilter_ipv4/ipt_ECN.h | 9 --
include/uapi/linux/nilfs2_ondisk.h | 28 ++---
include/uapi/linux/virtio_net.h | 7 +
scripts/headers-c++.sh | 124 +++++++++++++++++++++
25 files changed, 304 insertions(+), 166 deletions(-)
create mode 100644 fs/coda/coda_psdev.h
delete mode 100644 include/linux/coda_psdev.h
create mode 100644 include/linux/ndctl.h
create mode 100755 scripts/headers-c++.sh
David Howells
2018-Sep-06 09:18 UTC
[PATCH 03/11] UAPI: virtio_net: Fix use of C++ keywords as structural members [ver #2]
The virtio_net_ctrl_hdr struct uses a C++ keyword as structural members. Fix
this by inserting an anonymous union that provides an alternative name and
then hide the reserved name in C++.
Signed-off-by: David Howells <dhowells at redhat.com>
cc: "Michael S. Tsirkin" <mst at redhat.com>
cc: Jason Wang <jasowang at redhat.com>
cc: virtualization at lists.linux-foundation.org
---
include/uapi/linux/virtio_net.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index a3715a3224c1..967142bc0e05 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -150,7 +150,12 @@ struct virtio_net_hdr_mrg_rxbuf {
* command goes in between.
*/
struct virtio_net_ctrl_hdr {
- __u8 class;
+ union {
+#ifndef __cplusplus
+ __u8 class;
+#endif
+ __u8 _class;
+ };
__u8 cmd;
} __attribute__((packed));
Michael S. Tsirkin
2018-Sep-06 15:02 UTC
[PATCH 03/11] UAPI: virtio_net: Fix use of C++ keywords as structural members [ver #2]
On Thu, Sep 06, 2018 at 10:18:42AM +0100, David Howells wrote:> The virtio_net_ctrl_hdr struct uses a C++ keyword as structural members. Fix > this by inserting an anonymous union that provides an alternative name and > then hide the reserved name in C++. > > Signed-off-by: David Howells <dhowells at redhat.com> > cc: "Michael S. Tsirkin" <mst at redhat.com> > cc: Jason Wang <jasowang at redhat.com> > cc: virtualization at lists.linux-foundation.org > --- > > include/uapi/linux/virtio_net.h | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h > index a3715a3224c1..967142bc0e05 100644 > --- a/include/uapi/linux/virtio_net.h > +++ b/include/uapi/linux/virtio_net.h > @@ -150,7 +150,12 @@ struct virtio_net_hdr_mrg_rxbuf { > * command goes in between. > */ > struct virtio_net_ctrl_hdr { > - __u8 class; > + union { > +#ifndef __cplusplus > + __u8 class; > +#endif > + __u8 _class; > + }; > __u8 cmd; > } __attribute__((packed)); >So if we are going to do this, I think I'd prefer something like: struct virtio_net_ctrl_hdr_v2 { __u8 cmd_class; __u8 cmd; }; And then hide the whole old structure. This also gets rid of the packed keyword which we don't really need here. Only issue is virtio_net_ctrl_hdr_v2 is ugly. But oh well. And then rework at least QEMU to use the v2 of the header. Quite a bit of churn, so I don't think it makes sense to apply just this one in isolation - only if rest of the changes go in. -- MST