Re: [PATCH] [14/58] x86_64: Add on_cpu_single
> But probably you should just drop this ... with smp_call_function_single's > new semantics, I don't see this function growing any users. The new sched-clock uses it, but i'll update it to use smp_call_function_single Thanks -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] [14/58] x86_64: Add on_cpu_single
Hi Andi,
On 7/19/07, Andi Kleen <[EMAIL PROTECTED]> wrote:
Call a function on a target CPU but do the right thing when
we're already on that CPU. That's the main difference from
smp_call_function_single
which does the wrong thing in this case (erroring out)
I think this is no longer the case, is it? With KVM updates already
merged in latest mainline -git, that modified smp_call_function_single()
behaviour ...
+#ifdef CONFIG_SMP
+/* Similar to smp_call_function_single, but DTRT when we're already
+ on the right CPU. */
+static inline void on_cpu_single(int cpu, void (*func)(void *), void *info)
+{
+ int me = get_cpu();
+ if (cpu == me) {
+ func(info);
+ put_cpu();
+ } else {
+ put_cpu();
+ /* wait is forced on because the me==cpu case above will always
wait */
+ smp_call_function_single(cpu, func, info, 0, 1);
In any case, this is unsafe. smp_call_function_single() -- with the old
semantics, which is what this patch assumes, obviously -- is quite
pointless without its _caller_ disabling preemption around it. So the
put_cpu() must come after the smp_call_function_single, otherwise
you won't even detect the error that might happen, seeing you're
ignoring its return and this wrapper being void-returning.
+ }
+}
+#else
+static inline void on_cpu_single(int cpu, void (*func)(void *), void *info)
+{
WARN_ON(irqs_disabled());
local_irq_disable();
+ func(info);
local_irq_restore();
+}
+#endif
... for the sake of API / behaviour consistency.
But probably you should just drop this ... with smp_call_function_single's
new semantics, I don't see this function growing any users.
Satyam
-
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[PATCH] [14/58] x86_64: Add on_cpu_single
Call a function on a target CPU but do the right thing when
we're already on that CPU. That's the main difference from
smp_call_function_single
which does the wrong thing in this case (erroring out)
Another advantage is that it is also defined for the UP case, avoiding
some ifdefs.
I also dropped retry (which never did anything) and wait (because the on
current cpu case will always wait)
Signed-off-by: Andi Kleen <[EMAIL PROTECTED]>
---
include/linux/smp.h | 22 ++
1 file changed, 22 insertions(+)
Index: linux/include/linux/smp.h
===
--- linux.orig/include/linux/smp.h
+++ linux/include/linux/smp.h
@@ -138,4 +138,26 @@ static inline void smp_send_reschedule(i
void smp_setup_processor_id(void);
+#ifdef CONFIG_SMP
+/* Similar to smp_call_function_single, but DTRT when we're already
+ on the right CPU. */
+static inline void on_cpu_single(int cpu, void (*func)(void *), void *info)
+{
+ int me = get_cpu();
+ if (cpu == me) {
+ func(info);
+ put_cpu();
+ } else {
+ put_cpu();
+ /* wait is forced on because the me==cpu case above will always
wait */
+ smp_call_function_single(cpu, func, info, 0, 1);
+ }
+}
+#else
+static inline void on_cpu_single(int cpu, void (*func)(void *), void *info)
+{
+ func(info);
+}
+#endif
+
#endif /* __LINUX_SMP_H */
-
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Please read the FAQ at http://www.tux.org/lkml/
[PATCH] [14/58] x86_64: Add on_cpu_single
Call a function on a target CPU but do the right thing when
we're already on that CPU. That's the main difference from
smp_call_function_single
which does the wrong thing in this case (erroring out)
Another advantage is that it is also defined for the UP case, avoiding
some ifdefs.
I also dropped retry (which never did anything) and wait (because the on
current cpu case will always wait)
Signed-off-by: Andi Kleen [EMAIL PROTECTED]
---
include/linux/smp.h | 22 ++
1 file changed, 22 insertions(+)
Index: linux/include/linux/smp.h
===
--- linux.orig/include/linux/smp.h
+++ linux/include/linux/smp.h
@@ -138,4 +138,26 @@ static inline void smp_send_reschedule(i
void smp_setup_processor_id(void);
+#ifdef CONFIG_SMP
+/* Similar to smp_call_function_single, but DTRT when we're already
+ on the right CPU. */
+static inline void on_cpu_single(int cpu, void (*func)(void *), void *info)
+{
+ int me = get_cpu();
+ if (cpu == me) {
+ func(info);
+ put_cpu();
+ } else {
+ put_cpu();
+ /* wait is forced on because the me==cpu case above will always
wait */
+ smp_call_function_single(cpu, func, info, 0, 1);
+ }
+}
+#else
+static inline void on_cpu_single(int cpu, void (*func)(void *), void *info)
+{
+ func(info);
+}
+#endif
+
#endif /* __LINUX_SMP_H */
-
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the body of a message to [EMAIL PROTECTED]
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Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] [14/58] x86_64: Add on_cpu_single
Hi Andi,
On 7/19/07, Andi Kleen [EMAIL PROTECTED] wrote:
Call a function on a target CPU but do the right thing when
we're already on that CPU. That's the main difference from
smp_call_function_single
which does the wrong thing in this case (erroring out)
I think this is no longer the case, is it? With KVM updates already
merged in latest mainline -git, that modified smp_call_function_single()
behaviour ...
+#ifdef CONFIG_SMP
+/* Similar to smp_call_function_single, but DTRT when we're already
+ on the right CPU. */
+static inline void on_cpu_single(int cpu, void (*func)(void *), void *info)
+{
+ int me = get_cpu();
+ if (cpu == me) {
+ func(info);
+ put_cpu();
+ } else {
+ put_cpu();
+ /* wait is forced on because the me==cpu case above will always
wait */
+ smp_call_function_single(cpu, func, info, 0, 1);
In any case, this is unsafe. smp_call_function_single() -- with the old
semantics, which is what this patch assumes, obviously -- is quite
pointless without its _caller_ disabling preemption around it. So the
put_cpu() must come after the smp_call_function_single, otherwise
you won't even detect the error that might happen, seeing you're
ignoring its return and this wrapper being void-returning.
+ }
+}
+#else
+static inline void on_cpu_single(int cpu, void (*func)(void *), void *info)
+{
WARN_ON(irqs_disabled());
local_irq_disable();
+ func(info);
local_irq_restore();
+}
+#endif
... for the sake of API / behaviour consistency.
But probably you should just drop this ... with smp_call_function_single's
new semantics, I don't see this function growing any users.
Satyam
-
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] [14/58] x86_64: Add on_cpu_single
But probably you should just drop this ... with smp_call_function_single's new semantics, I don't see this function growing any users. The new sched-clock uses it, but i'll update it to use smp_call_function_single Thanks -Andi - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
