linux-kernel - Re: [PATCH 05/14] stallion: prune lock

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Message-Id: <201004292329.27799.arnd@arndb.de>
Date:	Thu, 29 Apr 2010 23:29:27 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Alan Cox <alan@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/14] stallion: prune lock_kernel calls

On Thursday 01 April 2010 18:05:19 Alan Cox wrote:
> @@ -4009,6 +4010,8 @@ static int stli_getbrdstats(combrd_t __user *bp)
>                 return -ENODEV;
>  
>         memset(&stli_brdstats, 0, sizeof(combrd_t));
> +
> +       mutex_lock(&portp->port.mutex);
>         stli_brdstats.brd = brdp->brdnr;
>         stli_brdstats.type = brdp->brdtype;
>         stli_brdstats.hwid = 0;
> @@ -4022,6 +4025,7 @@ static int stli_getbrdstats(combrd_t __user *bp)
>                 stli_brdstats.panels[i].hwid = brdp->panelids[i];
>                 stli_brdstats.panels[i].nrports = brdp->panels[i];
>         }
> +       mutex_unlock(&portp->port.mutex);
>  
>         if (copy_to_user(bp, &stli_brdstats, sizeof(combrd_t)))
>                 return -EFAULT;

I just tried porting my patches on top of yours (yes, it's been
some time). This one doesn't work, because there is no portp variable
in stli_getbrdstats.

On a related topic, in patch 06/14 "istallion: use bit ops for the board flags",
you have

> @@ -817,7 +817,7 @@ static int stli_open(struct tty_struct *tty, struct file *filp)
>         brdp = stli_brds[brdnr];
>         if (brdp == NULL)
>                 return -ENODEV;
> -       if ((brdp->state & BST_STARTED) == 0)
> +       if (!(test_bit(BST_STARTED, &brdp->state))
>                 return -ENODEV;
>         portnr = MINOR2PORT(minordev);
>        if (portnr > brdp->nrports)

This won't work because brdp->state is an 'unsigned int' variable, while
bitops only work on 'unsigned long'.

Maybe you sent out a wrong version of this file?

	Arnd
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