Re: [PATCH v5 1/8] smp: Introduce a generic on_each_cpu_mask function
From: Gilad Ben-Yossef <gilad@benyossef.com>
Date: 2012-01-08 16:04:19
Also in:
linux-fsdevel, lkml
On Wed, Jan 4, 2012 at 12:26 AM, Andrew Morton [off-list ref] wrote:
On Mon, 2 Jan 2012 12:24:12 +0200 Gilad Ben-Yossef [off-list ref] wrote:quoted
on_each_cpu_mask calls a function on processors specified my cpumask, which may include the local processor. All the limitation specified in smp_call_function_many apply. ...--- a/include/linux/smp.h +++ b/include/linux/smp.h@@ -102,6 +102,13 @@ static inline void call_function_init(void) { }int on_each_cpu(smp_call_func_t func, void *info, int wait); /* + * Call a function on processors specified by mask, which might include + * the local one. + */ +void on_each_cpu_mask(const struct cpumask *mask, void (*func)(void *), + void *info, bool wait); + +/* * Mark the boot cpu "online" so that it can call console drivers in * printk() and can access its per-cpu storage. */@@ -132,6 +139,15 @@ static inline int up_smp_call_function(smp_call_func_t func, void *info)local_irq_enable(); \ 0; \ }) +#define on_each_cpu_mask(mask, func, info, wait) \ + do { \ + if (cpumask_test_cpu(0, (mask))) { \ + local_irq_disable(); \ + (func)(info); \ + local_irq_enable(); \ + } \ + } while (0)Why is the cpumask_test_cpu() call there? It's hard to think of a reason why "mask" would specify any CPU other than "0" in a uniprocessor kernel.
As Michal already answered, because the current CPU might be not specified in the mask, even on UP.
If this code remains as-is, please add a comment here explaining this, so others don't wonder the same thing.
Comment added and will be included in V6. Thanks for the review. Gilad -- Gilad Ben-Yossef Chief Coffee Drinker gilad@benyossef.com Israel Cell: +972-52-8260388 US Cell: +1-973-8260388 http://benyossef.com "Unfortunately, cache misses are an equal opportunity pain provider." -- Mike Galbraith, LKML -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>