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Date: Mon, 2 Sep 2013 15:33:13 +0100
From: Javi Merino <javi.merino@....com>
To: linux-kernel@...r.kernel.org
Cc: Javi Merino <javi.merino@....com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] smp: harmonize prototypes of smp functions
Avoid unnecessary casts from int to bool in smp functions. Some
functions in kernel/smp.c have a wait parameter that can be set to one
if you want to wait for the command to complete. It's defined as bool
in a few of them and int in the rest. If a function with wait
declared as int calls a function whose prototype has wait defined as
bool, the compiler needs to test if the int is != 0 and change it to 1
if so. This useless check can be avoided if we are consistent and
make all the functions use the same type for this parameter.
For example in arm, before this patch:
800464e4 <smp_call_function>:
800464e4: b538 push {r3, r4, r5, lr}
800464e6: 460d mov r5, r1
800464e8: 4613 mov r3, r2 ; move wait to r3
800464ea: f64f 448c movw r4, #64652
800464ee: 3300 adds r3, #0 ; test if wait is 0
800464f0: f2c8 0425 movt r4, #32805
800464f4: 4601 mov r1, r0
800464f6: bf18 it ne
800464f8: 2301 movne r3, #1 ; if it is not, wait = 1
800464fa: 462a mov r2, r5
800464fc: 6820 ldr r0, [r4, #0]
800464fe: f7ff fea9 bl 80046254 <smp_call_function_many>
80046502: 2000 movs r0, #0
80046504: bd38 pop {r3, r4, r5, pc}
80046506: bf00 nop
After the patch:
800464e4 <smp_call_function>:
800464e4: b538 push {r3, r4, r5, lr}
800464e6: 460d mov r5, r1
800464e8: 4613 mov r3, r2 ; just move it to r3
800464ea: f64f 448c movw r4, #64652
800464ee: 4601 mov r1, r0
800464f0: f2c8 0425 movt r4, #32805
800464f4: 462a mov r2, r5
800464f6: 6820 ldr r0, [r4, #0]
800464f8: f7ff feac bl 80046254 <smp_call_function_many>
800464fc: 2000 movs r0, #0
800464fe: bd38 pop {r3, r4, r5, pc}
Same for x86. Before:
ffffffff8109bf10 <smp_call_function>:
ffffffff8109bf10: 55 push %rbp
ffffffff8109bf11: 48 89 e5 mov %rsp,%rbp
ffffffff8109bf14: 31 c9 xor %ecx,%ecx ; ecx = 0
ffffffff8109bf16: 85 d2 test %edx,%edx ; test if wait is 0
ffffffff8109bf18: 48 89 f2 mov %rsi,%rdx
ffffffff8109bf1b: 48 89 fe mov %rdi,%rsi
ffffffff8109bf1e: 48 8b 3d 4b d3 76 00 mov 0x76d34b(%rip),%rdi # ffffffff81809270 <cpu_online_mask>
ffffffff8109bf25: 0f 95 c1 setne %cl ; if it is not, ecx = 1
ffffffff8109bf28: e8 43 fc ff ff callq ffffffff8109bb70 <smp_call_function_many>
ffffffff8109bf2d: 31 c0 xor %eax,%eax
ffffffff8109bf2f: 5d pop %rbp
ffffffff8109bf30: c3 retq
After:
ffffffff8109bf20 <smp_call_function>:
ffffffff8109bf20: 55 push %rbp
ffffffff8109bf21: 48 89 e5 mov %rsp,%rbp
ffffffff8109bf24: 89 d1 mov %edx,%ecx ; just move wait to ecx
ffffffff8109bf26: 48 89 f2 mov %rsi,%rdx
ffffffff8109bf29: 48 89 fe mov %rdi,%rsi
ffffffff8109bf2c: 48 8b 3d 3d d3 76 00 mov 0x76d33d(%rip),%rdi # ffffffff81809270 <cpu_online_mask>
ffffffff8109bf33: e8 48 fc ff ff callq ffffffff8109bb80 <smp_call_function_many>
ffffffff8109bf38: 31 c0 xor %eax,%eax
ffffffff8109bf3a: 5d pop %rbp
ffffffff8109bf3b: c3 retq
ffffffff8109bf3c: 0f 1f 40 00 nopl 0x0(%rax)
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Javi Merino <javi.merino@....com>
---
include/linux/smp.h | 6 +++---
kernel/smp.c | 6 +++---
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/include/linux/smp.h b/include/linux/smp.h
index c181399..a894405 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -72,7 +72,7 @@ extern void smp_cpus_done(unsigned int max_cpus);
*/
int smp_call_function(smp_call_func_t func, void *info, int wait);
void smp_call_function_many(const struct cpumask *mask,
- smp_call_func_t func, void *info, bool wait);
+ smp_call_func_t func, void *info, int wait);
void __smp_call_function_single(int cpuid, struct call_single_data *data,
int wait);
@@ -104,7 +104,7 @@ int on_each_cpu(smp_call_func_t func, void *info, int wait);
* the local one.
*/
void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
- void *info, bool wait);
+ void *info, int wait);
/*
* Call a function on each processor for which the supplied function
@@ -112,7 +112,7 @@ void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
* processor.
*/
void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
- smp_call_func_t func, void *info, bool wait,
+ smp_call_func_t func, void *info, int wait,
gfp_t gfp_flags);
/*
diff --git a/kernel/smp.c b/kernel/smp.c
index fe9f773..f614250 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -367,7 +367,7 @@ void __smp_call_function_single(int cpu, struct call_single_data *csd,
* must be disabled when calling this function.
*/
void smp_call_function_many(const struct cpumask *mask,
- smp_call_func_t func, void *info, bool wait)
+ smp_call_func_t func, void *info, int wait)
{
struct call_function_data *cfd;
int cpu, next_cpu, this_cpu = smp_processor_id();
@@ -590,7 +590,7 @@ EXPORT_SYMBOL(on_each_cpu);
* from a hardware interrupt handler or from a bottom half handler.
*/
void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func,
- void *info, bool wait)
+ void *info, int wait)
{
int cpu = get_cpu();
@@ -632,7 +632,7 @@ EXPORT_SYMBOL(on_each_cpu_mask);
* from a hardware interrupt handler or from a bottom half handler.
*/
void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
- smp_call_func_t func, void *info, bool wait,
+ smp_call_func_t func, void *info, int wait,
gfp_t gfp_flags)
{
cpumask_var_t cpus;
--
1.7.9.5
--
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