On 08/25/2018 02:37 AM, John Fastabend wrote: > Currently, when a redirect occurs in sockmap and an error occurs in > the redirect call we unwind the scatterlist once in the error path > of bpf_tcp_sendmsg_do_redirect() and then again in sendmsg(). Then > in the error path of sendmsg we decrement the copied count by the > send size. > > However, its possible we partially sent data before the error was > generated. This can happen if do_tcp_sendpages() partially sends the > scatterlist before encountering a memory pressure error. If this > happens we need to decrement the copied value (the value tracking > how many bytes were actually sent to TCP stack) by the number of > remaining bytes _not_ the entire send size. Otherwise we risk > confusing userspace. > > Also we don't need two calls to free the scatterlist one is > good enough. So remove the one in bpf_tcp_sendmsg_do_redirect() and > then properly reduce copied by the number of remaining bytes which > may in fact be the entire send size if no bytes were sent. > > To do this use bool to indicate if free_start_sg() should do mem > accounting or not. > > Signed-off-by: John Fastabend <john.fastab...@gmail.com>
Applied to bpf, thanks John!
