On Thu, Mar 9, 2023 at 5:31 AM Paolo Abeni <pabeni@xxxxxxxxxx> wrote: > > On Tue, 2023-03-07 at 16:23 -0500, Xin Long wrote: > > diff --git a/net/sctp/stream_sched_fc.c b/net/sctp/stream_sched_fc.c > > new file mode 100644 > > index 000000000000..b336c2f5486b > > --- /dev/null > > +++ b/net/sctp/stream_sched_fc.c > > @@ -0,0 +1,183 @@ > > +// SPDX-License-Identifier: GPL-2.0-or-later > > +/* SCTP kernel implementation > > + * (C) Copyright Red Hat Inc. 2022 > > + * > > + * This file is part of the SCTP kernel implementation > > + * > > + * These functions manipulate sctp stream queue/scheduling. > > + * > > + * Please send any bug reports or fixes you make to the > > + * email addresched(es): > > + * lksctp developers <linux-sctp@xxxxxxxxxxxxxxx> > > + * > > + * Written or modified by: > > + * Xin Long <lucien.xin@xxxxxxxxx> > > + */ > > + > > +#include <linux/list.h> > > +#include <net/sctp/sctp.h> > > Note that the above introduces a new compile warning: > > ../net/sctp/stream_sched_fc.c: note: in included file (through ../include/net/sctp/sctp.h): > ../include/net/sctp/structs.h:335:41: warning: array of flexible structures > > that is not really a fault of the new code, it's due to: > > struct sctp_init_chunk peer_init[]; > > struct sctp_init_chunk { > struct sctp_chunkhdr chunk_hdr; > struct sctp_inithdr init_hdr; > }; > > struct sctp_inithdr { > __be32 init_tag; > __be32 a_rwnd; > __be16 num_outbound_streams; > __be16 num_inbound_streams; > __be32 initial_tsn; > __u8 params[]; // <- this! > }; > > Any chance a future patch could remove the 'params' field from the > struct included by sctp_init_chunk? > > e.g. > > struct sctp_inithdr_base { > __be32 init_tag; > __be32 a_rwnd; > __be16 num_outbound_streams; > __be16 num_inbound_streams; > __be32 initial_tsn; > }; > > struct sctp_init_chunk { > struct sctp_chunkhdr chunk_hdr; > struct sctp_inithdr_base init_hdr; > }; > > and then cast 'init_hdr' to 'struct sctp_inithdr' if/where needed. > > In any case, the above is not blocking this series. > Hi, Paolo, There are actually quite some warnings like this in SCTP: # make C=1 CF="-Wflexible-array-nested" M=./net/sctp/ 2> /tmp/warnings # grep "nested flexible array" /tmp/warnings |grep sctp |sort |uniq ./include/linux/sctp.h:230:29: warning: nested flexible array ./include/linux/sctp.h:278:29: warning: nested flexible array ./include/linux/sctp.h:348:29: warning: nested flexible array ./include/linux/sctp.h:393:29: warning: nested flexible array ./include/linux/sctp.h:451:28: warning: nested flexible array ./include/linux/sctp.h:611:32: warning: nested flexible array ./include/linux/sctp.h:628:33: warning: nested flexible array ./include/linux/sctp.h:675:30: warning: nested flexible array ./include/linux/sctp.h:735:29: warning: nested flexible array ./include/net/sctp/structs.h:1145:41: warning: nested flexible array ./include/net/sctp/structs.h:1588:28: warning: nested flexible array ./include/net/sctp/structs.h:343:28: warning: nested flexible array ./include/uapi/linux/sctp.h:641:34: warning: nested flexible array ./include/uapi/linux/sctp.h:643:34: warning: nested flexible array ./include/uapi/linux/sctp.h:644:33: warning: nested flexible array ./include/uapi/linux/sctp.h:650:40: warning: nested flexible array ./include/uapi/linux/sctp.h:653:39: warning: nested flexible array Other than the uapis, I can try to give others a cleanup by deleting these flexible array members and casting it by (struct xxx *) (hdr + 1) when accessing it. This warning is reported if a structure having a flexible array member is included by other structures, and I also noticed there is the same problem on some core structures like: struct ip_options struct nft_set_ext which are included in many other structures, and can also cause such warnings. I guess we'll just leave it as it is, right? Thanks.