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. 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
