2018-04-23 22:26 GMT+02:00 Michael S. Tsirkin <m...@redhat.com>:
> On Mon, Apr 23, 2018 at 10:15:18PM +0200, Björn Töpel wrote:
>> 2018-04-23 22:11 GMT+02:00 Michael S. Tsirkin <m...@redhat.com>:
>> > On Mon, Apr 23, 2018 at 10:00:15PM +0200, Björn Töpel wrote:
>> >> 2018-04-23 18:18 GMT+02:00 Michael S. Tsirkin <m...@redhat.com>:
>> >>
>> >> [...]
>> >>
>> >> >> +static void xdp_umem_unpin_pages(struct xdp_umem *umem)
>> >> >> +{
>> >> >> + unsigned int i;
>> >> >> +
>> >> >> + if (umem->pgs) {
>> >> >> + for (i = 0; i < umem->npgs; i++)
>> >> >
>> >> > Since you pin them with FOLL_WRITE, I assume these pages
>> >> > are written to.
>> >> > Don't you need set_page_dirty_lock here?
>> >> >
>> >>
>> >> Hmm, I actually *removed* it from the RFC V2, but after doing some
>> >> homework, I think you're right. Thanks for pointing this out!
>> >>
>> >> Thinking more about this; This function is called from sk_destruct,
>> >> and in the Tx case the sk_destruct can be called from interrupt
>> >> context, where set_page_dirty_lock cannot be called.
>> >>
>> >> Are there any preferred ways of solving this? Scheduling the whole
>> >> xsk_destruct call to a workqueue is one way (I think). Any
>> >> cleaner/better way?
>> >>
>> >> [...]
>> >
>> > Defer unpinning pages until the next tx call?
>> >
>>
>> If the sock is released, there wont be another tx call.
>
> unpin them on socket release too?
>
AF_XDP pins all memory up front, and unpins it when the socket is
released (final sock_put), which in this case is in the skb
destructor. So there's no later point from a sock lifetime
perspective.
I'll make a stab at doing umem clean up in a worker queue.
>> Or am I
>> missing something obvious?
>>
>> >
>> >> >> +static int __xdp_umem_reg(struct xdp_umem *umem, struct xdp_umem_reg
>> >> >> *mr)
>> >> >> +{
>> >> >> + u32 frame_size = mr->frame_size, frame_headroom =
>> >> >> mr->frame_headroom;
>> >> >> + u64 addr = mr->addr, size = mr->len;
>> >> >> + unsigned int nframes;
>> >> >> + int size_chk, err;
>> >> >> +
>> >> >> + if (frame_size < XDP_UMEM_MIN_FRAME_SIZE || frame_size >
>> >> >> PAGE_SIZE) {
>> >> >> + /* Strictly speaking we could support this, if:
>> >> >> + * - huge pages, or*
>> >> >
>> >> > what does "or*" here mean?
>> >> >
>> >>
>> >> Oops, I'll change to just 'or' in the next revision.
>> >>
>> >>
>> >> Thanks!
>> >> Björn
