Date: Sun, 25 Feb 2018 10:38:42 +0000 (UTC) From: Hans Petter Selasky <hselasky@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r329974 - stable/11/sys/compat/linuxkpi/common/include/asm Message-ID: <201802251038.w1PAcgGY018618@repo.freebsd.org>
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Author: hselasky Date: Sun Feb 25 10:38:42 2018 New Revision: 329974 URL: https://svnweb.freebsd.org/changeset/base/329974 Log: MFC r329523 and r329524: Fix implementation of xchg() function macro in the LinuxKPI. The exchange operation must be atomic. Sponsored by: Mellanox Technologies Modified: stable/11/sys/compat/linuxkpi/common/include/asm/atomic.h Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/compat/linuxkpi/common/include/asm/atomic.h ============================================================================== --- stable/11/sys/compat/linuxkpi/common/include/asm/atomic.h Sun Feb 25 10:37:07 2018 (r329973) +++ stable/11/sys/compat/linuxkpi/common/include/asm/atomic.h Sun Feb 25 10:38:42 2018 (r329974) @@ -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, __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: \ + __ret.val = READ_ONCE(*ptr); \ + while (!atomic_fcmpset_8((volatile u8 *)(ptr), \ + __ret.u8, __new.u8[0])) \ + ; \ + break; \ + case 2: \ + __ret.val = READ_ONCE(*ptr); \ + while (!atomic_fcmpset_16((volatile u16 *)(ptr), \ + __ret.u16, __new.u16[0])) \ + ; \ + break; \ + case 4: \ + __ret.u32[0] = atomic_swap_32((volatile u32 *)(ptr), \ + __new.u32[0]); \ + break; \ + case 8: \ + __ret.u64[0] = atomic_swap_64((volatile u64 *)(ptr), \ + __new.u64[0]); \ + break; \ + } \ + __ret.val; \ }) #define LINUX_ATOMIC_OP(op, c_op) \
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