percpu: Add {raw,this}_cpu_try_cmpxchg()

Add the try_cmpxchg() form to the per-cpu ops.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230531132323.587480729@infradead.org

diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index 6432a7f..96af32c 100644 (file)
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -89,16 +89,37 @@ do {                                                                        \
        __ret;                                                          \
 })
 
-#define raw_cpu_generic_cmpxchg(pcp, oval, nval)                       \
+#define __cpu_fallback_try_cmpxchg(pcp, ovalp, nval, _cmpxchg)         \
+({                                                                     \
+       typeof(pcp) __val, __old = *(ovalp);                            \
+       __val = _cmpxchg(pcp, __old, nval);                             \
+       if (__val != __old)                                             \
+               *(ovalp) = __val;                                       \
+       __val == __old;                                                 \
+})
+
+#define raw_cpu_generic_try_cmpxchg(pcp, ovalp, nval)                  \
 ({                                                                     \
        typeof(pcp) *__p = raw_cpu_ptr(&(pcp));                         \
-       typeof(pcp) __ret;                                              \
-       __ret = *__p;                                                   \
-       if (__ret == (oval))                                            \
+       typeof(pcp) __val = *__p, __old = *(ovalp);                     \
+       bool __ret;                                                     \
+       if (__val == __old) {                                           \
                *__p = nval;                                            \
+               __ret = true;                                           \
+       } else {                                                        \
+               *(ovalp) = __val;                                       \
+               __ret = false;                                          \
+       }                                                               \
        __ret;                                                          \
 })
 
+#define raw_cpu_generic_cmpxchg(pcp, oval, nval)                       \
+({                                                                     \
+       typeof(pcp) __old = (oval);                                     \
+       raw_cpu_generic_try_cmpxchg(pcp, &__old, nval);                 \
+       __old;                                                          \
+})
+
 #define raw_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
 ({                                                                     \
        typeof(pcp1) *__p1 = raw_cpu_ptr(&(pcp1));                      \
@@ -170,6 +191,16 @@ do {                                                                       \
        __ret;                                                          \
 })
 
+#define this_cpu_generic_try_cmpxchg(pcp, ovalp, nval)                 \
+({                                                                     \
+       bool __ret;                                                     \
+       unsigned long __flags;                                          \
+       raw_local_irq_save(__flags);                                    \
+       __ret = raw_cpu_generic_try_cmpxchg(pcp, ovalp, nval);          \
+       raw_local_irq_restore(__flags);                                 \
+       __ret;                                                          \
+})
+
 #define this_cpu_generic_cmpxchg(pcp, oval, nval)                      \
 ({                                                                     \
        typeof(pcp) __ret;                                              \
@@ -282,6 +313,43 @@ do {                                                                       \
 #define raw_cpu_xchg_8(pcp, nval)      raw_cpu_generic_xchg(pcp, nval)
 #endif
 
+#ifndef raw_cpu_try_cmpxchg_1
+#ifdef raw_cpu_cmpxchg_1
+#define raw_cpu_try_cmpxchg_1(pcp, ovalp, nval) \
+       __cpu_fallback_try_cmpxchg(pcp, ovalp, nval, raw_cpu_cmpxchg_1)
+#else
+#define raw_cpu_try_cmpxchg_1(pcp, ovalp, nval) \
+       raw_cpu_generic_try_cmpxchg(pcp, ovalp, nval)
+#endif
+#endif
+#ifndef raw_cpu_try_cmpxchg_2
+#ifdef raw_cpu_cmpxchg_2
+#define raw_cpu_try_cmpxchg_2(pcp, ovalp, nval) \
+       __cpu_fallback_try_cmpxchg(pcp, ovalp, nval, raw_cpu_cmpxchg_2)
+#else
+#define raw_cpu_try_cmpxchg_2(pcp, ovalp, nval) \
+       raw_cpu_generic_try_cmpxchg(pcp, ovalp, nval)
+#endif
+#endif
+#ifndef raw_cpu_try_cmpxchg_4
+#ifdef raw_cpu_cmpxchg_4
+#define raw_cpu_try_cmpxchg_4(pcp, ovalp, nval) \
+       __cpu_fallback_try_cmpxchg(pcp, ovalp, nval, raw_cpu_cmpxchg_4)
+#else
+#define raw_cpu_try_cmpxchg_4(pcp, ovalp, nval) \
+       raw_cpu_generic_try_cmpxchg(pcp, ovalp, nval)
+#endif
+#endif
+#ifndef raw_cpu_try_cmpxchg_8
+#ifdef raw_cpu_cmpxchg_8
+#define raw_cpu_try_cmpxchg_8(pcp, ovalp, nval) \
+       __cpu_fallback_try_cmpxchg(pcp, ovalp, nval, raw_cpu_cmpxchg_8)
+#else
+#define raw_cpu_try_cmpxchg_8(pcp, ovalp, nval) \
+       raw_cpu_generic_try_cmpxchg(pcp, ovalp, nval)
+#endif
+#endif
+
 #ifndef raw_cpu_cmpxchg_1
 #define raw_cpu_cmpxchg_1(pcp, oval, nval) \
        raw_cpu_generic_cmpxchg(pcp, oval, nval)
@@ -407,6 +475,43 @@ do {                                                                       \
 #define this_cpu_xchg_8(pcp, nval)     this_cpu_generic_xchg(pcp, nval)
 #endif
 
+#ifndef this_cpu_try_cmpxchg_1
+#ifdef this_cpu_cmpxchg_1
+#define this_cpu_try_cmpxchg_1(pcp, ovalp, nval) \
+       __cpu_fallback_try_cmpxchg(pcp, ovalp, nval, this_cpu_cmpxchg_1)
+#else
+#define this_cpu_try_cmpxchg_1(pcp, ovalp, nval) \
+       this_cpu_generic_try_cmpxchg(pcp, ovalp, nval)
+#endif
+#endif
+#ifndef this_cpu_try_cmpxchg_2
+#ifdef this_cpu_cmpxchg_2
+#define this_cpu_try_cmpxchg_2(pcp, ovalp, nval) \
+       __cpu_fallback_try_cmpxchg(pcp, ovalp, nval, this_cpu_cmpxchg_2)
+#else
+#define this_cpu_try_cmpxchg_2(pcp, ovalp, nval) \
+       this_cpu_generic_try_cmpxchg(pcp, ovalp, nval)
+#endif
+#endif
+#ifndef this_cpu_try_cmpxchg_4
+#ifdef this_cpu_cmpxchg_4
+#define this_cpu_try_cmpxchg_4(pcp, ovalp, nval) \
+       __cpu_fallback_try_cmpxchg(pcp, ovalp, nval, this_cpu_cmpxchg_4)
+#else
+#define this_cpu_try_cmpxchg_4(pcp, ovalp, nval) \
+       this_cpu_generic_try_cmpxchg(pcp, ovalp, nval)
+#endif
+#endif
+#ifndef this_cpu_try_cmpxchg_8
+#ifdef this_cpu_cmpxchg_8
+#define this_cpu_try_cmpxchg_8(pcp, ovalp, nval) \
+       __cpu_fallback_try_cmpxchg(pcp, ovalp, nval, this_cpu_cmpxchg_8)
+#else
+#define this_cpu_try_cmpxchg_8(pcp, ovalp, nval) \
+       this_cpu_generic_try_cmpxchg(pcp, ovalp, nval)
+#endif
+#endif
+
 #ifndef this_cpu_cmpxchg_1
 #define this_cpu_cmpxchg_1(pcp, oval, nval) \
        this_cpu_generic_cmpxchg(pcp, oval, nval)

diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index e60727b..cbbf6d1 100644 (file)
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -343,6 +343,21 @@ static __always_inline void __this_cpu_preempt_check(const char *op) { }
        pscr2_ret__;                                                    \
 })
 
+#define __pcpu_size_call_return2bool(stem, variable, ...)              \
+({                                                                     \
+       bool pscr2_ret__;                                               \
+       __verify_pcpu_ptr(&(variable));                                 \
+       switch(sizeof(variable)) {                                      \
+       case 1: pscr2_ret__ = stem##1(variable, __VA_ARGS__); break;    \
+       case 2: pscr2_ret__ = stem##2(variable, __VA_ARGS__); break;    \
+       case 4: pscr2_ret__ = stem##4(variable, __VA_ARGS__); break;    \
+       case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break;    \
+       default:                                                        \
+               __bad_size_call_parameter(); break;                     \
+       }                                                               \
+       pscr2_ret__;                                                    \
+})
+
 /*
  * Special handling for cmpxchg_double.  cmpxchg_double is passed two
  * percpu variables.  The first has to be aligned to a double word
@@ -426,6 +441,8 @@ do {                                                                        \
 #define raw_cpu_xchg(pcp, nval)                __pcpu_size_call_return2(raw_cpu_xchg_, pcp, nval)
 #define raw_cpu_cmpxchg(pcp, oval, nval) \
        __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
+#define raw_cpu_try_cmpxchg(pcp, ovalp, nval) \
+       __pcpu_size_call_return2bool(raw_cpu_try_cmpxchg_, pcp, ovalp, nval)
 #define raw_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
        __pcpu_double_call_return_bool(raw_cpu_cmpxchg_double_, pcp1, pcp2, oval1, oval2, nval1, nval2)
 
@@ -513,6 +530,8 @@ do {                                                                        \
 #define this_cpu_xchg(pcp, nval)       __pcpu_size_call_return2(this_cpu_xchg_, pcp, nval)
 #define this_cpu_cmpxchg(pcp, oval, nval) \
        __pcpu_size_call_return2(this_cpu_cmpxchg_, pcp, oval, nval)
+#define this_cpu_try_cmpxchg(pcp, ovalp, nval) \
+       __pcpu_size_call_return2bool(this_cpu_try_cmpxchg_, pcp, ovalp, nval)
 #define this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
        __pcpu_double_call_return_bool(this_cpu_cmpxchg_double_, pcp1, pcp2, oval1, oval2, nval1, nval2)