linux-kernel - Re: [RFC PATCH 06/13] driver core: firmware loader: always let firmware

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Date:	Wed, 25 Jul 2012 18:13:01 +0200
From:	Borislav Petkov <bp@...64.org>
To:	Ming Lei <ming.lei@...onical.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 06/13] driver core: firmware loader: always let
 firmware_buf own the pages buffer

On Wed, Jul 25, 2012 at 01:00:06AM +0800, Ming Lei wrote:
> This patch always let firmware_buf own the pages buffer allocated
> inside firmware_data_write, also add all instances of firmware_buf
> into the firmware cache global list. Also introduce one private field
> in 'struct firmware', so release_firmware will see the instance of
> firmware_buf associated with one firmware instance, then just 'free'
> the instance of firmware_buf.
> 
> The firmware_buf instance represents one pages buffer for one
> firmware image, so lots of firmware loading requests can share
> the same firmware_buf instance if they request the same firmware
> image file.
> 
> This patch will make introducing cache_firmware/uncache_firmware
> easily.
> 
> In fact, the patch improves request_formware/release_firmware:
> 
>         - only request userspace to write firmware image once if
> 	several devices share one same firmware image and its drivers
> 	call request_firmware concurrently.
> 
> Signed-off-by: Ming Lei <ming.lei@...onical.com>
> ---
>  drivers/base/firmware_class.c |  222 ++++++++++++++++++++++++++++-------------
>  include/linux/firmware.h      |    3 +
>  2 files changed, 157 insertions(+), 68 deletions(-)
> 
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index 986d9df..225898e 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -21,6 +21,7 @@
>  #include <linux/firmware.h>
>  #include <linux/slab.h>
>  #include <linux/sched.h>
> +#include <linux/list.h>
>  
>  MODULE_AUTHOR("Manuel Estrada Sainz");
>  MODULE_DESCRIPTION("Multi purpose firmware loading support");
> @@ -85,13 +86,18 @@ static inline long firmware_loading_timeout(void)
>  	return loading_timeout > 0 ? loading_timeout * HZ : MAX_SCHEDULE_TIMEOUT;
>  }
>  
> -/* fw_lock could be moved to 'struct firmware_priv' but since it is just
> - * guarding for corner cases a global lock should be OK */
> -static DEFINE_MUTEX(fw_lock);
> +struct firmware_cache {
> +

Stray newline. Sorry I missed it the first time.

> +	/* firmware_buf instance will be added into the below list */
> +	spinlock_t lock;
> +	struct list_head head;
> +};

[ … ]

-- 
Regards/Gruss,
Boris.

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