Messages in this thread | | | From | David Brownell <> | Subject | Re: [PATCH 3/5] watchdog: cleanup a bit omap_wdt.c | Date | Sat, 20 Sep 2008 08:32:14 -0700 |
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On Saturday 20 September 2008, Russell King - ARM Linux wrote: > On Fri, Sep 19, 2008 at 05:41:44PM -0700, David Brownell wrote: > > On Friday 19 September 2008, Felipe Balbi wrote: > > > static int omap_wdt_open(struct inode *inode, struct file *file) > > > { > > > - struct omap_wdt_dev *wdev; > > > - void __iomem *base; > > > - wdev = platform_get_drvdata(omap_wdt_dev); > > > - base = wdev->base; > > > + struct omap_wdt_dev *wdev = platform_get_drvdata(omap_wdt_dev); > > > + void __iomem *base = wdev->base; > > > + > > > > Oh, I see where "omap_wdt_dev" (global) gets used. The normal > > way to do stuff like that is using void* pointers placed in the > > inode and file structures for exactly that purpose. > > You don't have an inode or a file structure until open() is called - > at which point it _is_ placed in file->private_data. So this driver > is doing the right thing.
Well, the conventional thing for misc drivers, at any rate. In various other drivers, inode->i_private is set up earlier, just to avoid such a need for globals (or equivalent).
One could argue that this idiom is ugly ... and fix it by having misc_open() in drivers/char/misc.c initialize i_private before delegating to the miscdevice->fops->open(). Even just setting it to the miscdevice pointer would suffice with this driver; container_of(i_private, struct omap_wdt_dev, omap_wdt_miscdev) would then return what get_drvdata() returns, sans global.
But that wouldn't be just cleaning up this watchdog.
= Dave
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