sctp_assoc_update_frag_point() should be called whenever asoc->pathmtu changes, but we missed one place in sctp_association_init(). It would cause frag_point is zero when sending data. As says in Jakub's reproducer, if sp->pathmtu is set by socketopt, the new asoc->pathmtu inherits it in sctp_association_init(). Later when transports are added and their pmtu >= asoc->pathmtu, it will never call sctp_assoc_update_frag_point() to set frag_point. This patch is to fix it by updating frag_point after asoc->pathmtu is set as sp->pathmtu in sctp_association_init(). Note that it moved them after sctp_stream_init(), as stream->si needs to be set first. Frag_point's calculation is also related with datachunk's type, so it needs to update frag_point when stream->si may be changed in sctp_process_init(). v1->v2: - call sctp_assoc_update_frag_point() separately in sctp_process_init and sctp_association_init, per Marcelo's suggestion. Fixes: 2f5e3c9df693 ("sctp: introduce sctp_assoc_update_frag_point") Reported-by: Jakub Audykowicz <jakub.audykowicz@gmail.com> Signed-off-by: Xin Long <lucien.xin@gmail.com> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ There are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. Please read Documentation/admin-guide/README.rst first. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. The formatted documentation can also be read online at: https://www.kernel.org/doc/html/latest/ There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.
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