On Thu, 9 Feb 2012 10:36:21 +0200
Gilad Ben-Yossef <gilad@xxxxxxxxxxxxx> wrote:
> @@ -153,6 +162,22 @@ static inline int up_smp_call_function(smp_call_func_t func, void *info)
> local_irq_enable(); \
> } \
> } while (0)
> +/*
> + * Preemption is disabled here to make sure the
> + * cond_func is called under the same condtions in UP
> + * and SMP.
> + */
> +#define on_each_cpu_cond(cond_func, func, info, wait, gfp_flags) \
> + do {
> + void *__info = (info); \
> + preempt_disable(); \
> + if ((cond_func)(0, __info)) { \
> + local_irq_disable(); \
> + (func)(__info); \
> + local_irq_enable(); \
> + } \
> + preempt_enable(); \
> + } while (0)
That wasn't compile-tested!
This is one of the many reasons why I convert replacement patches into
incremental patches - so I can see what was done.
Here's what I queued after converting this patch into a delta:
--- a/kernel/smp.c~smp-add-func-to-ipi-cpus-based-on-parameter-func-v9
+++ a/kernel/smp.c
@@ -771,7 +771,9 @@ EXPORT_SYMBOL(on_each_cpu_mask);
* The function might sleep if the GFP flags indicates a non
* atomic allocation is allowed.
*
- * Preemption is disabled to protect against a hotplug event.
+ * Preemption is disabled to protect against CPU going offline but not
+ * online. CPUs going online during the call will not be seen or sent
+ * an IPI.
*
* You must not call this function with disabled interrupts or
* from a hardware interrupt handler or from a bottom half handler.
_
And I queued a small fix to that:
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: smp-add-func-to-ipi-cpus-based-on-parameter-func-v9-fix
s/CPU/CPUs, use all 80 cols in comment
Cc: Gilad Ben-Yossef <gilad@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/smp.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/kernel/smp.c~smp-add-func-to-ipi-cpus-based-on-parameter-func-v9-fix
+++ a/kernel/smp.c
@@ -771,9 +771,8 @@ EXPORT_SYMBOL(on_each_cpu_mask);
* The function might sleep if the GFP flags indicates a non
* atomic allocation is allowed.
*
- * Preemption is disabled to protect against CPU going offline but not
- * online. CPUs going online during the call will not be seen or sent
- * an IPI.
+ * Preemption is disabled to protect against CPUs going offline but not online.
+ * CPUs going online during the call will not be seen or sent an IPI.
*
* You must not call this function with disabled interrupts or
* from a hardware interrupt handler or from a bottom half handler.
_
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