On Tue, Nov 27, 2018 at 7:30 PM Xin Long <lucien.xin@xxxxxxxxx> wrote: > > On Mon, Nov 26, 2018 at 10:59 PM Neil Horman <nhorman@xxxxxxxxxxxxx> wrote: > > > > On Mon, Nov 26, 2018 at 10:46:33PM +0900, Xin Long wrote: > > > On Mon, Nov 26, 2018 at 9:54 PM Neil Horman <nhorman@xxxxxxxxxxxxx> wrote: > > > > > > > > On Mon, Nov 26, 2018 at 07:22:05PM +0800, Xin Long wrote: > > > > > Now when using stream reconfig to add out streams, stream->out > > > > > will get re-allocated, and all old streams' information will > > > > > be copied to the new ones and the old ones will be freed. > > > > > > > > > > So without stream->out_curr updated, next time when trying to > > > > > send from stream->out_curr stream, a panic would be caused. > > > > > > > > > > This patch is to define sctp_stream_out_copy used to update the > > > > > stream->out_curr pointer to the new stream when copying the old > > > > > streams' information. > > > > > > > > > > While at it, rename fa_copy to sctp_stream_in_copy. > > > > > > > > > > Fixes: 5bbbbe32a431 ("sctp: introduce stream scheduler foundations") > > > > > Reported-by: Ying Xu <yinxu@xxxxxxxxxx> > > > > > Reported-by: syzbot+e33a3a138267ca119c7d@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > > Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx> > > > > > --- > > > > > net/sctp/stream.c | 46 ++++++++++++++++++++++++++++++++-------------- > > > > > 1 file changed, 32 insertions(+), 14 deletions(-) > > > > > > > > > > diff --git a/net/sctp/stream.c b/net/sctp/stream.c > > > > > index 3892e76..0687eeb 100644 > > > > > --- a/net/sctp/stream.c > > > > > +++ b/net/sctp/stream.c > > > > > @@ -61,18 +61,6 @@ static void fa_free(struct flex_array *fa) > > > > > flex_array_free(fa); > > > > > } > > > > > > > > > > -static void fa_copy(struct flex_array *fa, struct flex_array *from, > > > > > - size_t index, size_t count) > > > > > -{ > > > > > - void *elem; > > > > > - > > > > > - while (count--) { > > > > > - elem = flex_array_get(from, index); > > > > > - flex_array_put(fa, index, elem, 0); > > > > > - index++; > > > > > - } > > > > > -} > > > > > - > > > > > static void fa_zero(struct flex_array *fa, size_t index, size_t count) > > > > > { > > > > > void *elem; > > > > > @@ -135,6 +123,36 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > > kfree(SCTP_SO(stream, i)->ext); > > > > > } > > > > > > > > > > +static void sctp_stream_in_copy(struct flex_array *fa, > > > > > + struct sctp_stream *stream, __u16 count) > > > > > +{ > > > > > + size_t index = 0; > > > > > + void *elem; > > > > > + > > > > > + count = min(count, stream->incnt); > > > > > + while (count--) { > > > > > + elem = flex_array_get(stream->in, index); > > > > > + flex_array_put(fa, index, elem, 0); > > > > > + index++; > > > > > + } > > > > > +} > > > > > + > > > > > +static void sctp_stream_out_copy(struct flex_array *fa, > > > > > + struct sctp_stream *stream, __u16 count) > > > > > +{ > > > > > + size_t index = 0; > > > > > + void *elem; > > > > > + > > > > > + count = min(count, stream->outcnt); > > > > > + while (count--) { > > > > > + elem = flex_array_get(stream->out, index); > > > > > + flex_array_put(fa, index, elem, 0); > > > > > + if (stream->out_curr == elem) > > > > > + stream->out_curr = flex_array_get(fa, index); > > > > > + index++; > > > > > + } > > > > > +} > > > > > + > > > > Seems like you are duplicating code here. I think you would be better off > > > > moving the fa_copy routine to the flex_array api (perhaps renaming it > > > > flex_array_copy), and then codig sctp_stream_*_copy as static inlines that just > > > > call the flex_array api to do the copy. As for setting the out_curr pointer, > > > > perhaps you should convert that to an index, so it can be looked up on demand, > > > changing to use index only for this may not worth it. > > > there is no API from flex_array to convert element to index either > > > the index is also the stream_id, but we didn't save it into stream_out > > > either, too. > > > > > Right, I'm saying it would be valuable to augment the flex_array api to include > > a copy function, as well as a pointer to index lookup element, that could have > > use beyond just sctp. > What do you think of this? > > It's not called in tx/rx path, so no performance problem caused. > Since only SCTP is using fa_xxx(), I will not move any to > lib/flex_array.c for now. > > +static size_t fa_index(struct flex_array *fa, void *elem, size_t count) > +{ > + size_t index = 0; > + > + while (count--) > + if (elem == flex_array_get(fa, index++)) > + break; sorry, I meant: while (count--) { if (elem == flex_array_get(fa, index)) break; index++; } > + > + return index; > +} > + > /* Migrates chunks from stream queues to new stream queues if needed, > * but not across associations. Also, removes those chunks to streams > * higher than the new max. > @@ -147,6 +158,13 @@ static int sctp_stream_alloc_out(struct > sctp_stream *stream, __u16 outcnt, > > if (stream->out) { > fa_copy(out, stream->out, 0, min(outcnt, stream->outcnt)); > + if (stream->out_curr) { > + size_t index = fa_index(stream->out, stream->out_curr, > + stream->outcnt); > + > + BUG_ON(index == stream->outcnt); > + stream->out_curr = flex_array_get(out, index); > + } > fa_free(stream->out); > } > > > > > > > so that it doesn't have to be updated here at all, or alternatively, just set it > > > > back to NULL here so that the selected scheduler will be forced to do the next > > > > lookup. > > > We can't set it back to NULL. Otherwise, the scheduler may go to > > > send other msg if the last msg (with multiple chunks) is not yet sent > > > out completely, which is not allowed when it's not I-Data chunk. > > > > > If setting it back to NULL isn't valid, then the above is your solution. > > > > > This is not much duplicating, and this can reduce few params. > > > I'm actually ok with this. > > > > > I know your ok with it, you wrote the patch :). I however, am not really ok > > with the duplication. I would like to see it collapsed, if its not going to > > create a significant performance impact. > > > > Neil > >