Hi,
On 10/04/2013 08:43 PM, Alan Stern wrote:
On Fri, 4 Oct 2013, Hans de Goede wrote:
+ struct usb_host_endpoint *ep, *eps[USB_MAXENDPOINTS];
That's a big array to put on the stack: 30 entries each containing 8
bytes (on a 64-bit arch).
I was wondering about this myself when I wrote this. What do you suggest
as an alternative, kmalloc an array with intf->cur_altsetting->desc.bNumEndpoints
pointers ?
Or simply do 30 pointers every time. 240 bytes isn't all that much for
kmalloc.
Right, the allocating intf->cur_altsetting->desc.bNumEndpoints versus 30
pointers is just an optimization. I was wondering more if it would be
ok here to do a kmalloc(..., GPF_KERNEL), or if this code path is
ever called under interrupt, or some such ?
Also do we allow C-99 style variable length arrays in the kernel ?
Then we could just put what ever we need on the stack (which almost always
will be way less then 240 bytes).
Regards,
Hans
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