From owner-freebsd-hackers  Sat Jan 15 19:32:50 2000
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Date: Sat, 15 Jan 2000 11:32:37 +0800 (WST)
From: Michael Kennett <mike@laurasia.com.au>
Message-Id: <200001150332.LAA24167@laurasia.com.au>
To: hackers@freebsd.org
Subject: Use of newbus in sys/pci/pci.c
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

Hello All,

I have a question on the sys/pci/pci.c code, and its use of the
newbus architecture. An example of the code in question is:

static struct resource *
pci_alloc_resource(device_t dev, device_t child, int type, int *rid,
		   u_long start, u_long end, u_long count, u_int flags)
{
	struct pci_devinfo *dinfo = device_get_ivars(child);
                                                ^^^^^   Looks wrong
	struct resource_list *rl = &dinfo->resources;

	return resource_list_alloc(rl, dev, child, type, rid,
				   start, end, count, flags);
}

I don't understand the line that extracts the ivars from the child
device.  Isn't it the case that the ivars are a property of the bus
device (dev)?  In any case, the child device might not be directly
descended from the pci bus (e.g. it could be attached thru' the
bridge isab0: <VIA 82C586 PCI-ISA bridge>).

It strikes me that the assignment is unsafe. I would have thought
that the code should be:

static struct resource *
pci_alloc_resource(device_t dev, device_t child, int type, int *rid,
		   u_long start, u_long end, u_long count, u_int flags)
{
	struct pci_devinfo *dinfo = device_get_ivars(dev);
                                                ^^^   CHANGED
	struct resource_list *rl = &dinfo->resources;

	return resource_list_alloc(rl, dev, child, type, rid,
				   start, end, count, flags);
}

Why are the ivars extracted from the child, and not the bus device?

Kind Regards,

Mike Kennett
(mike@laurasia.com.au)



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