linux-kernel - Re: [PATCH v2 04/13] PCI: acpiphp: remove 'name' parameter

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Message-ID: <20080923011648.GC1814@ldl.fc.hp.com>
Date:	Mon, 22 Sep 2008 19:16:48 -0600
From:	Alex Chiang <achiang@...com>
To:	Matthew Wilcox <matthew@....cx>
Cc:	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	jbarnes@...tuousgeek.org, kristen.c.accardi@...el.com,
	kaneshige.kenji@...fujitsu.com
Subject: Re: [PATCH v2 04/13] PCI: acpiphp: remove 'name' parameter

* Matthew Wilcox <matthew@....cx>:
> On Tue, Sep 09, 2008 at 04:00:22AM -0600, Alex Chiang wrote:
> > We do not need to manage our own name parameter, especially since
> > the PCI core can change it on our behalf, in the case of duplicate
> > slot names.
> 
> Looks good, just a question ...
> 
> >  	acpiphp_slot->slot = slot;
> > -	snprintf(slot->name, sizeof(slot->name), "%u", slot->acpi_slot->sun);
> > +	scnprintf(name, SLOT_NAME_SIZE, "%u", slot->acpi_slot->sun);
> >  
> 
> What's the difference between snprintf and scnprintf?

I think this may have already been answered somewhere else, but
scnprintf tells you number of characters that actually fits into
the buffer whereas snprintf tells you the number of characters
that _would_ have fit into the buffer it were big enough.

> And why were we bothering to use snprintf anyway?  For when we fall into a
> parallel universe where a u32 can have more than twenty digits?

Well, I think there are some in-flight patches that want to
change sun to a 64 bit value, which makes me think we want to
change SLOT_NAME_SIZE to 21...

/ac

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