| Message ID | 20231201112041.5260-1-jgross@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] xen/public: fix flexible array definitions | expand |
Hi Juergen, > On Dec 1, 2023, at 19:20, Juergen Gross <jgross@suse.com> wrote: > > Flexible arrays in public headers can be problematic with some > compilers. > > With XEN_FLEX_ARRAY_DIM there is a mechanism available to deal with > this issue, but care must be taken to not change the affected structs > in an incompatible way. > > So bump __XEN_LATEST_INTERFACE_VERSION__ and introduce a new macro > XENPV_FLEX_ARRAY_DIM which will be XENPV_FLEX_ARRAY_DIM with the > interface version being new enough and "1" (the value used today in > the affected headers) when the interface version is an old one. > > Replace the arr[1] instances (this includes the ones seen to be > problematic in recent Linux kernels [1]) with arr[XENPV_FLEX_ARRAY_DIM] > in order to avoid compilation errors. > > [1]: https://bugzilla.kernel.org/show_bug.cgi?id=217693 > > Signed-off-by: Juergen Gross <jgross@suse.com> Acked-by: Henry Wang <Henry.Wang@arm.com> # CHANGELOG Kind regards, Henry
On 01.12.2023 12:20, Juergen Gross wrote: > Flexible arrays in public headers can be problematic with some > compilers. > > With XEN_FLEX_ARRAY_DIM there is a mechanism available to deal with > this issue, but care must be taken to not change the affected structs > in an incompatible way. > > So bump __XEN_LATEST_INTERFACE_VERSION__ and introduce a new macro > XENPV_FLEX_ARRAY_DIM which will be XENPV_FLEX_ARRAY_DIM with the > interface version being new enough and "1" (the value used today in > the affected headers) when the interface version is an old one. > > Replace the arr[1] instances (this includes the ones seen to be > problematic in recent Linux kernels [1]) with arr[XENPV_FLEX_ARRAY_DIM] > in order to avoid compilation errors. > > [1]: https://bugzilla.kernel.org/show_bug.cgi?id=217693 > > Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> > --- a/xen/include/public/io/ring.h > +++ b/xen/include/public/io/ring.h > @@ -25,8 +25,16 @@ > * and grant_table.h from the Xen public headers. > */ > > +#include "../xen.h" > #include "../xen-compat.h" Just to mention it: While perhaps good practice, I'm not convinced this extra #include is actually needed here. > +/* Some PV I/O interfaces need a compatibility variant. */ > +#if __XEN_INTERFACE_VERSION__ < 0x00041300 > +#define XENPV_FLEX_ARRAY_DIM 1 /* variable size */ > +#else > +#define XENPV_FLEX_ARRAY_DIM XEN_FLEX_ARRAY_DIM > +#endif > + > #if __XEN_INTERFACE_VERSION__ < 0x00030208 > #define xen_mb() mb() > #define xen_rmb() rmb() > @@ -110,7 +118,7 @@ struct __name##_sring { \ > uint8_t pvt_pad[4]; \ > } pvt; \ > uint8_t __pad[44]; \ > - union __name##_sring_entry ring[1]; /* variable-length */ \ > + union __name##_sring_entry ring[XENPV_FLEX_ARRAY_DIM]; \ > }; \ > \ > /* "Front" end's private variables */ \ > @@ -479,7 +487,7 @@ struct name##_data_intf { \ > uint8_t pad2[56]; \ > \ > RING_IDX ring_order; \ > - grant_ref_t ref[]; \ > + grant_ref_t ref[XEN_FLEX_ARRAY_DIM]; \ > }; \ > DEFINE_XEN_FLEX_RING(name) >
On 01/12/2023 11:20, Juergen Gross wrote: > Flexible arrays in public headers can be problematic with some > compilers. > > With XEN_FLEX_ARRAY_DIM there is a mechanism available to deal with > this issue, but care must be taken to not change the affected structs > in an incompatible way. > > So bump __XEN_LATEST_INTERFACE_VERSION__ and introduce a new macro > XENPV_FLEX_ARRAY_DIM which will be XENPV_FLEX_ARRAY_DIM with the > interface version being new enough and "1" (the value used today in > the affected headers) when the interface version is an old one. > > Replace the arr[1] instances (this includes the ones seen to be > problematic in recent Linux kernels [1]) with arr[XENPV_FLEX_ARRAY_DIM] > in order to avoid compilation errors. > > [1]: https://bugzilla.kernel.org/show_bug.cgi?id=217693 > > Signed-off-by: Juergen Gross <jgross@suse.com> Acked-by: Julien Grall <jgrall@amazon.com> Cheers,
diff --git a/CHANGELOG.md b/CHANGELOG.md index 4ecebb9f68..5ee5d41fc9 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -7,6 +7,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) ## [4.19.0 UNRELEASED](https://xenbits.xenproject.org/gitweb/?p=xen.git;a=shortlog;h=staging) - TBD ### Changed + - Changed flexible array definitions in public I/O interface headers to not + use "1" as the number of array elements. ### Added - On x86: diff --git a/xen/include/public/io/cameraif.h b/xen/include/public/io/cameraif.h index 13763abef9..a389443769 100644 --- a/xen/include/public/io/cameraif.h +++ b/xen/include/public/io/cameraif.h @@ -763,7 +763,7 @@ struct xencamera_buf_create_req { */ struct xencamera_page_directory { grant_ref_t gref_dir_next_page; - grant_ref_t gref[1]; /* Variable length */ + grant_ref_t gref[XENPV_FLEX_ARRAY_DIM]; }; /* diff --git a/xen/include/public/io/displif.h b/xen/include/public/io/displif.h index 73d0cbdf15..132c96fa5c 100644 --- a/xen/include/public/io/displif.h +++ b/xen/include/public/io/displif.h @@ -537,7 +537,7 @@ struct xendispl_dbuf_create_req { struct xendispl_page_directory { grant_ref_t gref_dir_next_page; - grant_ref_t gref[1]; /* Variable length */ + grant_ref_t gref[XENPV_FLEX_ARRAY_DIM]; }; /* diff --git a/xen/include/public/io/fsif.h b/xen/include/public/io/fsif.h index ec57850233..dcade1c698 100644 --- a/xen/include/public/io/fsif.h +++ b/xen/include/public/io/fsif.h @@ -40,7 +40,7 @@ struct fsif_read_request { int32_t pad; uint64_t len; uint64_t offset; - grant_ref_t grefs[1]; /* Variable length */ + grant_ref_t grefs[XENPV_FLEX_ARRAY_DIM]; }; struct fsif_write_request { @@ -48,7 +48,7 @@ struct fsif_write_request { int32_t pad; uint64_t len; uint64_t offset; - grant_ref_t grefs[1]; /* Variable length */ + grant_ref_t grefs[XENPV_FLEX_ARRAY_DIM]; }; struct fsif_stat_request { diff --git a/xen/include/public/io/pvcalls.h b/xen/include/public/io/pvcalls.h index 230b0719e3..c8c7602470 100644 --- a/xen/include/public/io/pvcalls.h +++ b/xen/include/public/io/pvcalls.h @@ -30,7 +30,7 @@ struct pvcalls_data_intf { uint8_t pad2[52]; RING_IDX ring_order; - grant_ref_t ref[]; + grant_ref_t ref[XEN_FLEX_ARRAY_DIM]; }; DEFINE_XEN_FLEX_RING(pvcalls); diff --git a/xen/include/public/io/ring.h b/xen/include/public/io/ring.h index 0cae4367be..a79d913142 100644 --- a/xen/include/public/io/ring.h +++ b/xen/include/public/io/ring.h @@ -25,8 +25,16 @@ * and grant_table.h from the Xen public headers. */ +#include "../xen.h" #include "../xen-compat.h" +/* Some PV I/O interfaces need a compatibility variant. */ +#if __XEN_INTERFACE_VERSION__ < 0x00041300 +#define XENPV_FLEX_ARRAY_DIM 1 /* variable size */ +#else +#define XENPV_FLEX_ARRAY_DIM XEN_FLEX_ARRAY_DIM +#endif + #if __XEN_INTERFACE_VERSION__ < 0x00030208 #define xen_mb() mb() #define xen_rmb() rmb() @@ -110,7 +118,7 @@ struct __name##_sring { \ uint8_t pvt_pad[4]; \ } pvt; \ uint8_t __pad[44]; \ - union __name##_sring_entry ring[1]; /* variable-length */ \ + union __name##_sring_entry ring[XENPV_FLEX_ARRAY_DIM]; \ }; \ \ /* "Front" end's private variables */ \ @@ -479,7 +487,7 @@ struct name##_data_intf { \ uint8_t pad2[56]; \ \ RING_IDX ring_order; \ - grant_ref_t ref[]; \ + grant_ref_t ref[XEN_FLEX_ARRAY_DIM]; \ }; \ DEFINE_XEN_FLEX_RING(name) diff --git a/xen/include/public/io/sndif.h b/xen/include/public/io/sndif.h index 4234a47c87..cce1459b7b 100644 --- a/xen/include/public/io/sndif.h +++ b/xen/include/public/io/sndif.h @@ -659,7 +659,7 @@ struct xensnd_open_req { struct xensnd_page_directory { grant_ref_t gref_dir_next_page; - grant_ref_t gref[1]; /* Variable length */ + grant_ref_t gref[XENPV_FLEX_ARRAY_DIM]; }; /* diff --git a/xen/include/public/xen-compat.h b/xen/include/public/xen-compat.h index 97fe698498..078b796664 100644 --- a/xen/include/public/xen-compat.h +++ b/xen/include/public/xen-compat.h @@ -10,7 +10,7 @@ #ifndef __XEN_PUBLIC_XEN_COMPAT_H__ #define __XEN_PUBLIC_XEN_COMPAT_H__ -#define __XEN_LATEST_INTERFACE_VERSION__ 0x00040e00 +#define __XEN_LATEST_INTERFACE_VERSION__ 0x00041300 #if defined(__XEN__) || defined(__XEN_TOOLS__) /* Xen is built with matching headers and implements the latest interface. */
Flexible arrays in public headers can be problematic with some compilers. With XEN_FLEX_ARRAY_DIM there is a mechanism available to deal with this issue, but care must be taken to not change the affected structs in an incompatible way. So bump __XEN_LATEST_INTERFACE_VERSION__ and introduce a new macro XENPV_FLEX_ARRAY_DIM which will be XENPV_FLEX_ARRAY_DIM with the interface version being new enough and "1" (the value used today in the affected headers) when the interface version is an old one. Replace the arr[1] instances (this includes the ones seen to be problematic in recent Linux kernels [1]) with arr[XENPV_FLEX_ARRAY_DIM] in order to avoid compilation errors. [1]: https://bugzilla.kernel.org/show_bug.cgi?id=217693 Signed-off-by: Juergen Gross <jgross@suse.com> --- V2: - bump interface version and make change only for new version (Jan Beulich) V3: - move XENPV_FLEX_ARRAY_DIM definition to ring.h (Jan Beulich) - fix 2 wrong XENPV_FLEX_ARRAY_DIM use cases (Julien Grall) - add CHANGELOG.md entry (Andrew Cooper) --- CHANGELOG.md | 2 ++ xen/include/public/io/cameraif.h | 2 +- xen/include/public/io/displif.h | 2 +- xen/include/public/io/fsif.h | 4 ++-- xen/include/public/io/pvcalls.h | 2 +- xen/include/public/io/ring.h | 12 ++++++++++-- xen/include/public/io/sndif.h | 2 +- xen/include/public/xen-compat.h | 2 +- 8 files changed, 19 insertions(+), 9 deletions(-)