Messages in this thread | | | Date | Fri, 18 Jul 2008 21:53:41 +0400 | From | Evgeniy Polyakov <> | Subject | Re: [PATCH] tcp: do not promote SPLICE_F_NONBLOCK to socket O_NONBLOCK |
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Hi.
On Fri, Jul 18, 2008 at 08:04:44PM +0300, Octavian Purdila (opurdila@ixiacom.com) wrote: > Suppose we have 20 packets in the socket queue and the pipe is empty and the > application calls splice(sock, pipe, 17, flags=0). > > Then, tcp_splice_read will be called, which in turn calls tcp_read_sock. > > tcp_read_sock will loop until all the 17 bytes will be read from the socket. > tcp_read_sock calls skb_splice_bits which calls splice_to_pipe.
How come? spd_fill_page() should fail when it will be called for the 17'th skb and all reading from the socket will return, and thus can be sent to the file.
> Now while skb_splice_bits is carefull to only put a maximum of PIPE_BUFFERS > during its iteration, due to the looping in tcp_read_sock, we will end up > with 17 calls to splice_to_pipe. Thus on the 17th call, splice_to_pipe will > block.
Where exactly? Why tcp_splice_data_recv()->skb_splice_bits()->__skb_splice_bits()->spd_fill_page() callchain does not return error and that pipe is full?
-- Evgeniy Polyakov
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