Author: hselasky Date: Sun Feb 18 17:37:23 2018 New Revision: 329523 URL: https://svnweb.freebsd.org/changeset/base/329523
Log:
Fix implementation of xchg() function macro in the LinuxKPI.
The exchange operation must be atomic.
MFC after: 1 week
Sponsored by: Mellanox Technologies
Modified:
head/sys/compat/linuxkpi/common/include/asm/atomic.h
Modified: head/sys/compat/linuxkpi/common/include/asm/atomic.h
==============================================================================
--- head/sys/compat/linuxkpi/common/include/asm/atomic.h Sun Feb 18
16:41:34 2018 (r329522)
+++ head/sys/compat/linuxkpi/common/include/asm/atomic.h Sun Feb 18
17:37:23 2018 (r329523)
@@ -198,12 +198,41 @@ atomic_cmpxchg(atomic_t *v, int old, int new)
#define cmpxchg_relaxed(...) cmpxchg(__VA_ARGS__)
-#define xchg(ptr, v) ({ \
- __typeof(*(ptr)) __ret; \
- \
- __ret = *(ptr); \
- *(ptr) = v; \
- __ret; \
+#define xchg(ptr, new) ({
\
+ union { \
+ __typeof(*(ptr)) val; \
+ u8 u8[0]; \
+ u16 u16[0]; \
+ u32 u32[0]; \
+ u64 u64[0]; \
+ } __ret = { .val = READ_ONCE(*ptr) }, __new = { .val = (new) }; \
+ \
+ CTASSERT(sizeof(__ret.val) == 1 || sizeof(__ret.val) == 2 || \
+ sizeof(__ret.val) == 4 || sizeof(__ret.val) == 8); \
+ \
+ switch (sizeof(__ret.val)) { \
+ case 1: \
+ while (!atomic_fcmpset_8((volatile u8 *)(ptr), \
+ __ret.u8, __new.u8[0])) \
+ ; \
+ break; \
+ case 2: \
+ while (!atomic_fcmpset_16((volatile u16 *)(ptr), \
+ __ret.u16, __new.u16[0])) \
+ ; \
+ break; \
+ case 4: \
+ while (!atomic_fcmpset_32((volatile u32 *)(ptr), \
+ __ret.u32, __new.u32[0])) \
+ ; \
+ break; \
+ case 8: \
+ while (!atomic_fcmpset_64((volatile u64 *)(ptr), \
+ __ret.u64, __new.u64[0])) \
+ ; \
+ break; \
+ } \
+ __ret.val; \
})
#define LINUX_ATOMIC_OP(op, c_op) \
_______________________________________________
svn-src-head@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
