Re: [PATCH] workqueue: Add the allocation flags to function schedule_on_each_cpu_gfp

[yalin wang]

> On Aug 3, 2015, at 16:27, Minfei Huang <mnfhuang@xxxxxxxxx> wrote:
> 
> Rename the function schedule_on_each_cpu to schedule_on_each_cpu_gfp to
> add the allocation flags as parameter.
> 
> In several situation in ftrace, we are nervous and never come back, once
> schedule_on_each_cpu fails to alloc the percpu work. Add the allocation
> flags __GFP_NOFAIL to guarantee it.
> 
> Signed-off-by: Minfei Huang <mnfhuang@xxxxxxxxx>
> ---
> arch/x86/platform/uv/uv_time.c |  2 +-
> include/linux/ftrace.h         |  2 +-
> include/linux/workqueue.h      |  2 +-
> kernel/trace/ftrace.c          |  5 +++--
> kernel/trace/trace_events.c    |  2 +-
> kernel/workqueue.c             | 11 ++++++-----
> 6 files changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/platform/uv/uv_time.c b/arch/x86/platform/uv/uv_time.c
> index a244237..a87a16a 100644
> --- a/arch/x86/platform/uv/uv_time.c
> +++ b/arch/x86/platform/uv/uv_time.c
> @@ -405,7 +405,7 @@ static __init int uv_rtc_setup_clock(void)
> 	clock_event_device_uv.max_delta_ns = clocksource_uv.mask *
> 				(NSEC_PER_SEC / sn_rtc_cycles_per_second);
> 
> -	rc = schedule_on_each_cpu(uv_rtc_register_clockevents);
> +	rc = schedule_on_each_cpu_gfp(uv_rtc_register_clockevents, GFP_KERNEL);
> 	if (rc) {
> 		x86_platform_ipi_callback = NULL;
> 		uv_rtc_deallocate_timers();
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index 6cd8c0e..d6d3cf5 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -154,7 +154,7 @@ struct ftrace_ops_hash {
>  *
>  * Any private data added must also take care not to be freed and if private
>  * data is added to a ftrace_ops that is in core code, the user of the
> - * ftrace_ops must perform a schedule_on_each_cpu() before freeing it.
> + * ftrace_ops must perform a schedule_on_each_cpu_gfp() before freeing it.
>  */
> struct ftrace_ops {
> 	ftrace_func_t			func;
> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
> index 738b30b..2de50fe 100644
> --- a/include/linux/workqueue.h
> +++ b/include/linux/workqueue.h
> @@ -436,7 +436,7 @@ extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
> extern void flush_workqueue(struct workqueue_struct *wq);
> extern void drain_workqueue(struct workqueue_struct *wq);
> 
> -extern int schedule_on_each_cpu(work_func_t func);
> +extern int schedule_on_each_cpu_gfp(work_func_t func, gfp_t gfp);
> 
> int execute_in_process_context(work_func_t fn, struct execute_work *);
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index eb11011..f8d3111 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -324,7 +324,7 @@ static void update_ftrace_function(void)
> 	 * Make sure all CPUs see this. Yes this is slow, but static
> 	 * tracing is slow and nasty to have enabled.
> 	 */
> -	schedule_on_each_cpu(ftrace_sync);
> +	schedule_on_each_cpu_gfp(ftrace_sync, GFP_KERNEL | __GFP_NOFAIL);
> 	/* Now all cpus are using the list ops. */
> 	function_trace_op = set_function_trace_op;
> 	/* Make sure the function_trace_op is visible on all CPUs */
> @@ -2716,7 +2716,8 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
> 	 * ourselves.
> 	 */
> 	if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_CONTROL)) {
> -		schedule_on_each_cpu(ftrace_sync);
> +		schedule_on_each_cpu_gfp(ftrace_sync,
> +				GFP_KERNEL | __GFP_NOFAIL);
> 
> 		arch_ftrace_trampoline_free(ops);
> 
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 404a372..6cf0dba 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -2722,7 +2722,7 @@ static __init int event_test_thread(void *unused)
> 	if (!test_malloc)
> 		pr_info("failed to kmalloc\n");
> 
> -	schedule_on_each_cpu(test_work);
> +	schedule_on_each_cpu_gfp(test_work, GFP_KERNEL);
> 
> 	kfree(test_malloc);
> 
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 4c4f061..f7ef6bb 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -2917,22 +2917,23 @@ bool cancel_delayed_work_sync(struct delayed_work *dwork)
> EXPORT_SYMBOL(cancel_delayed_work_sync);
> 
> /**
> - * schedule_on_each_cpu - execute a function synchronously on each online CPU
> + * schedule_on_each_cpu_gfp - execute function synchronously on each online CPU
>  * @func: the function to call
> + * @gfp: allocation flags
>  *
> - * schedule_on_each_cpu() executes @func on each online CPU using the
> + * schedule_on_each_cpu_gfp() executes @func on each online CPU using the
>  * system workqueue and blocks until all CPUs have completed.
> - * schedule_on_each_cpu() is very slow.
> + * schedule_on_each_cpu_gfp() is very slow.
>  *
>  * Return:
>  * 0 on success, -errno on failure.
>  */
> -int schedule_on_each_cpu(work_func_t func)
> +int schedule_on_each_cpu_gfp(work_func_t func, gfp_t gfp)
> {
> 	int cpu;
> 	struct work_struct __percpu *works;
> 
> -	works = alloc_percpu(struct work_struct);
> +	works = alloc_percpu_gfp(struct work_struct, gfp);
> 	if (!works)
> 		return -ENOMEM;
> 
> -- 
> 2.4.0
> 
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better to also provide a wrapper function with name schedule_on_each_cpu(), 
as this function is used frequently .

#define schedule_on_each_cpu(f)  schedule_on_each_cpu_gfp(f, GFP_KERNEL) 

Thanks







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