With fast xnsynch/mutex support in place, the importance of getting the
user space library configuration right increases significantly. If the
user fails to provide --enable-smp, (s)he risks to break the mutex fast
path in a very subtle way.
This patch catches the case that the kernel support SMP while userland
does not.
Signed-off-by: Jan Kiszka <[EMAIL PROTECTED]>
---
include/asm-generic/features.h | 40 ++++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)
Index: b/include/asm-generic/features.h
===================================================================
--- a/include/asm-generic/features.h
+++ b/include/asm-generic/features.h
@@ -26,13 +26,14 @@
#endif /* __KERNEL__ */
#define __xn_feat_smp 0x80000000
-#define __xn_feat_fastsynch 0x40000000
-#define __xn_feat_nofastsynch 0x20000000
+#define __xn_feat_nosmp 0x40000000
+#define __xn_feat_fastsynch 0x20000000
+#define __xn_feat_nofastsynch 0x10000000
#ifdef CONFIG_SMP
#define __xn_feat_smp_mask __xn_feat_smp
#else
-#define __xn_feat_smp_mask 0
+#define __xn_feat_smp_mask __xn_feat_nosmp
#endif
#ifdef CONFIG_XENO_FASTSYNCH
@@ -41,22 +42,29 @@
#define __xn_feat_fastsynch_mask __xn_feat_nofastsynch
#endif
-#define __xn_feat_generic_mask (__xn_feat_smp_mask |
__xn_feat_fastsynch_mask)
-
-#define __xn_feat_generic_man_mask (__xn_feat_fastsynch |
__xn_feat_nofastsynch)
+/* List of generic features kernel or userland may support */
+#define __xn_feat_generic_mask \
+ (__xn_feat_smp_mask | __xn_feat_fastsynch_mask)
+
+/* List of features both sides have to agree on:
+ If userland supports it, the kernel has to provide it, too. */
+#define __xn_feat_generic_man_mask \
+ (__xn_feat_fastsynch | __xn_feat_nofastsynch | __xn_feat_nosmp)
static inline const char *get_generic_feature_label (unsigned feature)
{
- switch (feature) {
- case __xn_feat_smp:
- return "smp";
- case __xn_feat_fastsynch:
- return "fastsynch";
- case __xn_feat_nofastsynch:
- return "nofastsynch";
- default:
- return 0;
- }
+ switch (feature) {
+ case __xn_feat_smp:
+ return "smp";
+ case __xn_feat_nosmp:
+ return "nosmp";
+ case __xn_feat_fastsynch:
+ return "fastsynch";
+ case __xn_feat_nofastsynch:
+ return "nofastsynch";
+ default:
+ return 0;
+ }
}
#endif /* !_XENO_ASM_GENERIC_FEATURES_H */
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