Jeff Garzik wrote:
Mark Lord wrote:
Mark Lord wrote:
Today I've been using 2.6.25-rc8 with an old embedded build system here
for my empegs. One shell script calls out to /usr/bin/ftp to transfer
an image to a remote system, and then read it back again and compare.
The compare is failing, most (but not all) of the time,
but only on 2.6.25-rc8, not on 2.6.24. Verified by switching
back and forth between kernel versions for a short spell.
The ftp client is netkit-ftp 0.17-16 on Kubuntu feisty.
Switching to ncftpput/ncftpget avoids it on 2.6.25,
but I wonder where the problem is.
..
Now verified that the data loss occurs in the outbound direction.
The readback data is the same, regardless of which client s/w is used.
So something in 2.6.25 is incompatible with the ftp client binary, or
libs, that are installed here. Or some other problem.
Or maybe it uses sendfile, and that is broken?
..
No, it uses read()/write() calls (from the strace).
Here's the most recent update:
Recap, with more info:
The host system is running 2.6.25-rc8-git. It uses netkit-ftp to
send a file to the remote system. Using strace shows that the
entire file was read, and passed to write() for the outbound socket.
The remote system is running linux-2.2.xx, and is reporting -EPIPE
from net/socket.c::sock_recvmsg() before all of the data has been received,
and thus ends up with a short file, missing data at the end.
This exact sequence, with the exact same software,
works fine when the host system is NOT running 2.6.25-*,
(eg. 2.6.11 through 2.6.24 are fine).
Something may be broken here.
..
The failing FTP client software issues a close() on the socket after
the final data write(). This close seems to be propagated to the other
end before the data is fully received.
I suppose a wireshark capture is next, once I dig out my ancient hub
so we can sniff it from an independent box.
-ml
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