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(-)
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(-)
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. */
--
2.35.3On 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, -- Julien Grall
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)
>
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
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