linux-kernel - Re: [PATCH] staging: unisys: uislib: uisqueue.c: fixed sparse warning of context imbalance

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Date:	Tue, 2 Sep 2014 20:44:27 +0530
From:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	Benjamin Romer <benjamin.romer@...sys.com>,
	David Kershner <david.kershner@...sys.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	devel@...verdev.osuosl.org, sparmaintainer@...sys.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: unisys: uislib: uisqueue.c: fixed sparse
 warning of context imbalance

On Tue, Sep 02, 2014 at 05:05:32PM +0300, Dan Carpenter wrote:
> On Tue, Sep 02, 2014 at 04:39:47PM +0530, Sudip Mukherjee wrote:
> > fixed sparse warning : context imbalance in 'do_locked_client_insert'
> > 			 different lock contexts for basic block
> > 
> > spin_unlock_irqrestore is called at a later stage before returning 
> > from the function if locked is 1.
> > 
> > Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
> 
> This doesn't match the email address you are using.
> 

for all my patch the Signed-off email address is different from the From email address.
I am not sure if I should do that, but since no one pointed it out so I guessed it is ok.

> Really, your patch isn't bad but I would prefer if you re-wrote this
> entire function because currently it is garbage.
> 
> static u8
> do_locked_client_insert(struct uisqueue_info *queueinfo,
>                         unsigned int whichqueue,
>                         void *pSignal,
>                         spinlock_t *lock,
>                         unsigned char issueInterruptIfEmpty,
>                         u64 interruptHandle, u8 *channelId)
> {
>         unsigned long flags;
>         unsigned char queueWasEmpty;
> 
>         spin_lock_irqsave(lock, flags);
> 
>         if (!ULTRA_CHANNEL_CLIENT_ACQUIRE_OS(queueinfo->chan, channelId, NULL))
>                 goto unlock;
> 
>         queueWasEmpty = visor_signalqueue_empty(queueinfo->chan, whichqueue);
>         if (!visor_signal_insert(queueinfo->chan, whichqueue, pSignal))
>                 goto release;
>         ULTRA_CHANNEL_CLIENT_RELEASE_OS(queueinfo->chan, channelId, NULL);
>         spin_unlock_irqrestore(lock, flags);
> 
>         queueinfo->packets_sent++;
> 
>         return 1;
> 
> release:
>         ULTRA_CHANNEL_CLIENT_RELEASE_OS(queueinfo->chan, channelId, NULL);
> unlock:
>         spin_unlock_irqrestore(lock, flags);
> 
>         return 0;
> }
> 
> The queueWasEmpty variable is kind of silly.  It should just be an int
> or maybe a bool if you are being pedantic but instead we very
> specifically set it to be an unsigned variable of the incorrect type.
> Also we don't use queueWasEmpty at all.  I think we could delete it...
> 
> The problem with the original code was that the error paths and the
> success paths were mixed together like spaghetti.  If you separate them
> out and unwind in the proper order with normal label names then the
> code is easy to understand.
> 
> regards,
> dan carpenter
> 
I will send a modified patch with the required changes.

thanks
sudip

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