David Miller wrote:
From: Chuck Lever <[email protected]>
Date: Tue, 23 Oct 2007 11:44:28 -0400
The get_seconds() function returns an unsigned long. To prevent incorrect
comparison results between values saved in ts_recent_stamp and later
invocations of get_seconds(), change the type of ts_recent_stamp to match
the return type of get_seconds().
Signed-off-by: Chuck Lever <[email protected]>
Cc: <[email protected]>
I see two potential problems with this patch:
1) If you update struct tcp_options_received you should also
update struct tcp_timewait_sock similarly.
The fact that you missed this suggests that you didn't
grep the tree to see how else this variable is used and
this makes me extra concerned about this patch's correctness.
Perhaps the result of wishful thinking on my part. I was hoping for a
small and self-contained change.
2) There are computations in the TCP stack using this member that
probably care about the signedness, such as:
net/ipv4/tcp_ipv4.c: get_seconds() - tcptw->tw_ts_recent_stamp > 1))) {
include/net/tcp.h: if (get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)
include/net/tcp.h: if (get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)
We should make sure we understand what is expected here, and
why it would still be correct after making both ts_recent_stamp
members unsigned.
Agreed.
I wonder how one could construct a series of mixed case time stamp
comparisons *on purpose* (and without documentation of this assumption)
that produces consistently correct results.
From the invocations of get_seconds() that I sampled, the design of
these comparisons seems to assume that both sides of the comparison are
non-negative. However, they do not seem to account for time crossing zero.
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