Zhao, Yu wrote:
Matthew Wilcox wrote:
On Mon, Oct 27, 2008 at 03:13:51PM +0800, Zhao, Yu wrote:
Matthew Wilcox wrote:
On Mon, Oct 27, 2008 at 11:18:43AM +0800, Zhao, Yu wrote:
Matthew Wilcox wrote:
Yes, that's why pci_find_device() is deprecated. But it doesn't also
need to be buggy ;-)
How about pci_get_bus_and_slot()? People would meet the problem with it
anyway.
What problem with it? It's documented to return the device with an
increased refcount, and the implementation appears to do exactly that:
The 'dev' returned by pci_get_device() may be destroyed by PCI hotplug.
I suppose that passing this 'dev' to pci_get_device() in the next loop
would crash the system, right?
Erm, no, the 'dev' cannot be destroyed because the caller has a refcount
on it. The physical device backing it might have gone away. The dev
Why does the caller have a reference count? I don't see we increase the
reference count after the 'dev' is returned by following in
pci_get_dev_by_id():
dev = bus_find_device(&pci_bus_type, dev_start, (void *)id,
match_pci_dev_by_id);
And this 'dev' becomes the 'from' in the next loop, but it may be
destroyed before the 'pci_dev_get(from)', isn't it?
I checked the source code, there is no 'pci_dev_get(from)', the
reference count is increased in bus_find_device().
while ((dev = next_device(&i)))
if (match(dev, data) && get_device(dev))
But the essential problem is same: the reference count of 'dev' above
may be decreased before the 'get_device(dev)', I guess.
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