On Fri, 25 Dec 2015, Steinar H. Gunderson wrote:
> On Fri, Dec 25, 2015 at 09:50:50AM +0100, Oliver Neukum wrote:
> > > + ret = usbfs_increase_memory_usage(size + sizeof(struct
> > > usb_memory));
> > > + if (ret) {
> > > + module_put(THIS_MODULE);
> > > + return ret;
> > > + }
> >
> > Could you do the error handling in a unified manner with "goto"?
>
> Yes and no. I couldn't do it fully unified; note the error path below that
> uses usbfs_decrease_memory_usage() instead. I could do it sort-of-unified,
> but it ended up being one of those label cascades, of course:
>
> return 0;
>
> error_free_usbm:
> kfree(usbm);
> error_decrease_mem:
> usbfs_decrease_memory_usage(size + sizeof(struct usb_memory));
> error_module_put:
> module_put(THIS_MODULE);
> return ret;
That's okay; lots of drivers do this and people expect it. It also
reduces the total amount of code.
> > > + mem = usb_alloc_coherent(ps->dev, size, GFP_KERNEL, &dma_handle);
> > Shouldn't this be GFP_USER to let limits apply?
>
> This I don't really know anything about. Alan?
There doesn't appear to be very much difference between them. As far
as I can tell from the documentation in include/linux/gfp.h, GPF_USER
would indeed be more appropriate.
Alan Stern
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