[PATCH] dma-mapping: make map_benchmark compile into module

[PATCH] dma-mapping: make map_benchmark compile into module

[Tian Tao]

under some scenarios, it is necessary to compile map_benchmark
into module to test iommu, so this patch changed Kconfig and
export_symbol to implement map_benchmark compiled into module.

On the other hand, map_benchmark is a driver, which is supposed
to be able to run as a module.

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
---
 kernel/dma/Kconfig | 2 +-
 kernel/kthread.c   | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index 77b4055..0468293 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -223,7 +223,7 @@ config DMA_API_DEBUG_SG
 	  If unsure, say N.
 
 config DMA_MAP_BENCHMARK
-	bool "Enable benchmarking of streaming DMA mapping"
+	tristate "Enable benchmarking of streaming DMA mapping"
 	depends on DEBUG_FS
 	help
 	  Provides /sys/kernel/debug/dma_map_benchmark that helps with testing
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 1578973..fa4736f 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -455,6 +455,7 @@ void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask)
 {
 	__kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE);
 }
+EXPORT_SYMBOL(kthread_bind_mask);
 
 /**
  * kthread_bind - bind a just-created kthread to a cpu.
-- 
2.7.4

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RE: [PATCH] dma-mapping: make map_benchmark compile into module

[Song Bao Hua (Barry Song)]

> -----Original Message-----
> From: tiantao (H)
> Sent: Wednesday, March 24, 2021 3:18 PM
> To: akpm@linux-foundation.org; peterz@infradead.org; paulmck@kernel.org;
> ast@kernel.org; tglx@linutronix.de; rostedt@goodmis.org; hch@lst.de;
> m.szyprowski@samsung.com; Song Bao Hua (Barry Song)
> <song.bao.hua@hisilicon.com>
> Cc: iommu@lists.linux-foundation.org; linux-kernel@vger.kernel.org; tiantao
> (H) <tiantao6@hisilicon.com>
> Subject: [PATCH] dma-mapping: make map_benchmark compile into module
> 
> under some scenarios, it is necessary to compile map_benchmark
> into module to test iommu, so this patch changed Kconfig and
> export_symbol to implement map_benchmark compiled into module.
> 
> On the other hand, map_benchmark is a driver, which is supposed
> to be able to run as a module.
> 
> Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
> ---

Acked-by: Barry Song <song.bao.hua@hisilicon.com>

Look sensible to me. I like the idea that map_benchmark is
a driver. It seems unreasonable to always require built-in.


>  kernel/dma/Kconfig | 2 +-
>  kernel/kthread.c   | 1 +
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
> index 77b4055..0468293 100644
> --- a/kernel/dma/Kconfig
> +++ b/kernel/dma/Kconfig
> @@ -223,7 +223,7 @@ config DMA_API_DEBUG_SG
>  	  If unsure, say N.
> 
>  config DMA_MAP_BENCHMARK
> -	bool "Enable benchmarking of streaming DMA mapping"
> +	tristate "Enable benchmarking of streaming DMA mapping"
>  	depends on DEBUG_FS
>  	help
>  	  Provides /sys/kernel/debug/dma_map_benchmark that helps with testing
> diff --git a/kernel/kthread.c b/kernel/kthread.c
> index 1578973..fa4736f 100644
> --- a/kernel/kthread.c
> +++ b/kernel/kthread.c
> @@ -455,6 +455,7 @@ void kthread_bind_mask(struct task_struct *p, const struct
> cpumask *mask)
>  {
>  	__kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE);
>  }
> +EXPORT_SYMBOL(kthread_bind_mask);
> 
>  /**
>   * kthread_bind - bind a just-created kthread to a cpu.
> --
> 2.7.4

Thanks
Barry

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Re: [PATCH] dma-mapping: make map_benchmark compile into module

[Christoph Hellwig]

On Wed, Mar 24, 2021 at 10:17:38AM +0800, Tian Tao wrote:
> under some scenarios, it is necessary to compile map_benchmark
> into module to test iommu, so this patch changed Kconfig and
> export_symbol to implement map_benchmark compiled into module.
> 
> On the other hand, map_benchmark is a driver, which is supposed
> to be able to run as a module.
> 
> Signed-off-by: Tian Tao <tiantao6@hisilicon.com>

Nope, we're not going to export more kthread internals for a test
module.
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RE: [PATCH] dma-mapping: make map_benchmark compile into module

[Song Bao Hua (Barry Song)]

> -----Original Message-----
> From: Christoph Hellwig [mailto:hch@lst.de]
> Sent: Wednesday, March 24, 2021 8:13 PM
> To: tiantao (H) <tiantao6@hisilicon.com>
> Cc: akpm@linux-foundation.org; peterz@infradead.org; paulmck@kernel.org;
> ast@kernel.org; tglx@linutronix.de; rostedt@goodmis.org; hch@lst.de;
> m.szyprowski@samsung.com; Song Bao Hua (Barry Song)
> <song.bao.hua@hisilicon.com>; iommu@lists.linux-foundation.org;
> linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] dma-mapping: make map_benchmark compile into module
> 
> On Wed, Mar 24, 2021 at 10:17:38AM +0800, Tian Tao wrote:
> > under some scenarios, it is necessary to compile map_benchmark
> > into module to test iommu, so this patch changed Kconfig and
> > export_symbol to implement map_benchmark compiled into module.
> >
> > On the other hand, map_benchmark is a driver, which is supposed
> > to be able to run as a module.
> >
> > Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
> 
> Nope, we're not going to export more kthread internals for a test
> module.

The requirement comes from an colleague who is frequently changing
the map-bench code for some customized test purpose. and he doesn't
want to build kernel image and reboot every time. So I moved the
requirement to Tao Tian.

Right now, kthread_bind() is exported, kthread_bind_mask() seems
to be a little bit "internal" as you said, maybe a wrapper like
kthread_bind_node() won't be that "internal", comparing to exposing
the cpumask?
Anyway, we don't find other driver users for this, hardly I can
convince you it is worth.

Thanks
Barry
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Re: [PATCH] dma-mapping: make map_benchmark compile into module

[Christoph Hellwig]

On Wed, Mar 24, 2021 at 07:33:23AM +0000, Song Bao Hua (Barry Song) wrote:
> The requirement comes from an colleague who is frequently changing
> the map-bench code for some customized test purpose. and he doesn't
> want to build kernel image and reboot every time. So I moved the
> requirement to Tao Tian.
> 
> Right now, kthread_bind() is exported, kthread_bind_mask() seems
> to be a little bit "internal" as you said, maybe a wrapper like
> kthread_bind_node() won't be that "internal", comparing to exposing
> the cpumask?

I really don't think we should be exporting more low-level kthread
APIs.  Especially as we've been trying to get most users off the
kthread API and to workqueues instead.
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