Date: Sun, 18 Feb 2018 17:37:23 +0000 (UTC) From: Hans Petter Selasky <hselasky@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r329523 - head/sys/compat/linuxkpi/common/include/asm Message-ID: <201802181737.w1IHbNW6081247@repo.freebsd.org>
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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) \
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