linux-kernel - Re: [PATCH 1/2] drivers: staging: wilc1000: Move spin lock to the start of critical section

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Message-ID: <20151004100713.GA27051@gcs-HP-Notebook>
Date:	Sun, 4 Oct 2015 15:37:13 +0530
From:	Chandra Gorentla <csgorentla@...il.com>
To:	Greg KH <gregkh@...uxfoundation.org>
Cc:	rachel.kim@...el.com, devel@...verdev.osuosl.org,
	chris.park@...el.com, linux-wireless@...r.kernel.org,
	johnny.kim@...el.com, linux-kernel@...r.kernel.org,
	dan.carpenter@...cle.com
Subject: Re: [PATCH 1/2] drivers: staging: wilc1000: Move spin lock to the
 start of critical section

On Sun, Oct 04, 2015 at 09:43:35AM +0100, Greg KH wrote:
> On Sat, Oct 03, 2015 at 02:57:29PM +0530, Chandra S Gorentla wrote:
> > The spin_lock_irqsave is moved to just beginning of critical section.
> > This change moves a couple of return statements out of the lock.
> > 
> > Signed-off-by: Chandra S Gorentla <csgorentla@...il.com>
> > ---
> >  drivers/staging/wilc1000/wilc_msgqueue.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/staging/wilc1000/wilc_msgqueue.c b/drivers/staging/wilc1000/wilc_msgqueue.c
> > index d5ebd6d..284a3f5 100644
> > --- a/drivers/staging/wilc1000/wilc_msgqueue.c
> > +++ b/drivers/staging/wilc1000/wilc_msgqueue.c
> > @@ -72,8 +72,6 @@ int wilc_mq_send(WILC_MsgQueueHandle *pHandle,
> >  		goto ERRORHANDLER;
> >  	}
> >  
> > -	spin_lock_irqsave(&pHandle->strCriticalSection, flags);
> > -
> >  	/* construct a new message */
> >  	pstrMessage = kmalloc(sizeof(Message), GFP_ATOMIC);
> 
> As you have moved the lock, can you also change this to GFP_KERNEL as
> well because we do not have a lock held?
Can 'the change to GFP_KERNEL' be done in a separate patch?
The lock is to protect linked list manipulations; in this function items
are added to the list.
> 
> And how have you tested that this is ok?  What is this lock trying to
> protect?
I load this module on a notebook computer.   I added some code to
wilc_debugfs.c to invoke the functions in the file wilc_msgqueue.c
> 
> thanks,
> 
> greg k-h
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