Hello,
It seems like linux replaces sock with tcp_tw_bucket structure in the
sock list in order to "work around the memory consumption problems for
the heavilly loaded server".
The header file tcp.h has some comments before declaring
"tcp_tw_bucket" structure. It is done in tcp_input.c.
But anyway, tcp_tw_bucket is never identical to sock structure. This
is a serious hack and I'm suprised no linux kernel documentation talks
about it.
I just wanted to let others know so that no one else faces this
problem.
-- Sourav> > im a kernel newbie here so pardon "the blind leading the blind" ... > > doing a quick search for all calls to sk_alloc in the entire kernel > sources > yields only one call that sets the "zero out the allocated struct" > boolean > to false and that is: > net/ipv4/tcp_minisocks.c:tcp_create_openreq_child(). > this funtion in turn is only ever called from: > net/ipv[46]/tcp_ipv[46].c:tcp_v[46]_syn_recv_sock() > > the comment above the ipv4 version is (verbatim): > > /* > * The three way handshake has completed - we got a valid synack - > * now create the new socket. > */ > > so if you need those experimental values of yours zeroed out on socket > creation i suggest replacing this snippet from > net/core/sock.c:sk_alloc() > > if(sk && zero_it) { > memset(sk, 0, sizeof(struct sock)); > sk->family = family; > sock_lock_init(sk); > } > > with > > if( sk ) { > /* set your NULL init values here */ > if( zero_it ) { > memset(sk, 0, sizeof(struct sock)); > sk->family = family; > sock_lock_init(sk); > } > } > > doh! i just re-read your mail and realized youre using the 2.2.15 > kernel. > my examples are from the 2.4.2 sources... > > looking at the 2.2.16 source (i have only 2.2.1[46] and not 2.2.15 for > the > 2.2 series) the (roughly) congruent if block of code is: > > if(sk) { > if (zero_it) > memset(sk, 0, sizeof(struct sock)); > sk->family = family; > } > > and so if you're setting your init values to NULL under the "zero_it" > condition you would get the behavior that you reported. > > hope that helps.
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This archive was generated by hypermail 2b29 : Wed Feb 28 2001 - 21:00:08 EST