Re: [PATCH 3/5] staging: vme: add functions for bridge modulerefcounting

From: Emilio G. Cota
Date: Mon Aug 15 2011 - 14:49:28 EST

On Mon, Aug 15, 2011 at 12:05:03 +0200, Manohar Vanga wrote:
> > If the driver doesn't provide a .probe, we would still increment
> > the refcount of the bridge module. Is that reasonable? I dunno.
> I picked this default behaviour from the PCI driver code (drivers/pci/pci-driver.c):
> static int pci_device_probe(struct device * dev)
> {
> ...
> pci_dev_get(pci_dev);
> error = __pci_device_probe(drv, pci_dev);
> if (error)
> pci_dev_put(pci_dev);
> return error;
> }
> The __pci_device_probe() function checks if probe is present or not.

There is a subtle difference here; pci_dev is the _struct pci_device
of the device_ being probed, and pci_dev_get increments its refcount.

In our case vme_bridge_get increments the refcount of the _bridge's
module_; my concern was that if there was no .probe (which would
only happen with a few special drivers), we'd increment the refcount
of the bridge for perhaps no reason.

Anyway we don't have such esoteric drivers yet, so I wouldn't worry
about this too much.

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