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In the existing dn_route.c code, dn_route_output_slow() takes dst->__refcnt before calling dn_insert_route() while dn_route_input_slow() does not take dst->__refcnt before calling dn_insert_route(). This makes the whole routing code very buggy. In dn_dst_check_expire(), dnrt_free() is called when rt expires. This makes the routes inserted by dn_route_output_slow() not able to be freed as the refcnt is not released. In dn_dst_gc(), dnrt_drop() is called to release rt which could potentially cause the dst->__refcnt to be dropped to -1. In dn_run_flush(), dst_free() is called to release all the dst. Again, it makes the dst inserted by dn_route_output_slow() not able to be released and also, it does not wait on the rcu and could potentially cause crash in the path where other users still refer to this dst. This patch makes sure both input and output path do not take dst->__refcnt before calling dn_insert_route() and also makes sure dnrt_free()/dst_free() is called when removing dst from the hash table. The only difference between those 2 calls is that dnrt_free() waits on the rcu while dst_free() does not. Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.