[PATCH 1/1] staging: usbip: remove an unnecessary lock in usbip_event_happened. The variable "happened" is local. So I think there is no need to lock here.

[PATCH 1/1] staging: usbip: remove an unnecessary lock in usbip_event_happened. The variable "happened" is local. So I think there is no need to lock here.

[Harvey Yang]

From: harvey.yang <harvey.huawei.yang@gmail.com>


Signed-off-by: harvey.yang <harvey.huawei.yang@gmail.com>
---
 drivers/staging/usbip/usbip_event.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/usbip/usbip_event.c b/drivers/staging/usbip/usbip_event.c
index d332a34..668f8e0 100644
--- a/drivers/staging/usbip/usbip_event.c
+++ b/drivers/staging/usbip/usbip_event.c
@@ -116,10 +116,8 @@ int usbip_event_happened(struct usbip_device *ud)
 {
 	int happened = 0;
 
-	spin_lock(&ud->lock);
 	if (ud->event != 0)
 		happened = 1;
-	spin_unlock(&ud->lock);
 
 	return happened;
 }
-- 
1.7.1

Re: [PATCH 1/1] staging: usbip: remove an unnecessary lock in usbip_event_happened. The variable "happened" is local. So I think there is no need to lock here.

[Greg Kroah-Hartman]

On Mon, Nov 05, 2012 at 12:50:26PM +0800, Harvey Yang wrote:
> From: harvey.yang <harvey.huawei.yang@gmail.com>
> 
> 
> Signed-off-by: harvey.yang <harvey.huawei.yang@gmail.com>
> ---
>  drivers/staging/usbip/usbip_event.c |    2 --
>  1 files changed, 0 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/usbip/usbip_event.c b/drivers/staging/usbip/usbip_event.c
> index d332a34..668f8e0 100644
> --- a/drivers/staging/usbip/usbip_event.c
> +++ b/drivers/staging/usbip/usbip_event.c
> @@ -116,10 +116,8 @@ int usbip_event_happened(struct usbip_device *ud)
>  {
>  	int happened = 0;
>  
> -	spin_lock(&ud->lock);
>  	if (ud->event != 0)
>  		happened = 1;
> -	spin_unlock(&ud->lock);
>  
>  	return happened;

Are you sure that the real fix for this isn't just making 'happened' a
static variable?  That would make more sense here.  Well maybe, the code
seems pretty dumb, it's hard to tell what this is supposed to be doing,
any ideas?

thanks,

greg k-h

Re: [PATCH 1/1] staging: usbip: remove an unnecessary lock in usbip_event_happened. The variable "happened" is local. So I think there is no need to lock here.

[Prashant Shah]

Hi,

>         int happened = 0;
>
> -       spin_lock(&ud->lock);
>         if (ud->event != 0)
>                 happened = 1;
> -       spin_unlock(&ud->lock);
>
>         return happened;

I am guessing locking was intended to protect ud->event along with
happened so that (checking the value of ud->event and setting value of
happened) was atomic.

return ud->event != 0 ? 1 : 0;

Regards.

Re: [PATCH 1/1] staging: usbip: remove an unnecessary lock in usbip_event_happened. The variable "happened" is local. So I think there is no need to lock here.

[harvey yang]

I think no need to make 'happened' static as we just check 'ud->event'
feild. Maybe making this function inline would make more sense.

inline int usbip_event_happened(struct usbip_device *ud)
{
        return ud->event ? 1 : 0;
}

Thanks
Harvey


On Mon, Nov 5, 2012 at 1:34 PM, Prashant Shah <kerneldev100@gmail.com> wrote:
> Hi,
>
>>         int happened = 0;
>>
>> -       spin_lock(&ud->lock);
>>         if (ud->event != 0)
>>                 happened = 1;
>> -       spin_unlock(&ud->lock);
>>
>>         return happened;
>
> I am guessing locking was intended to protect ud->event along with
> happened so that (checking the value of ud->event and setting value of
> happened) was atomic.
>
> return ud->event != 0 ? 1 : 0;
>
> Regards.