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time: jiffies_delta_to_clock_t() helper to the rescue

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Various /proc/net files sometimes report crazy timer values, expressed
in clock_t units.

This happens when an expired timer delta (expires - jiffies) is passed
to jiffies_to_clock_t().

This function has an overflow in :

return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);

commit cbbc719fcc (time: Change jiffies_to_clock_t() argument type
to unsigned long) only got around the problem.

As we cant output negative values in /proc/net/tcp without breaking
various tools, I suggest adding a jiffies_delta_to_clock_t() wrapper
that caps the negative delta to a 0 value.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Maciej Żenczykowski <maze@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: hank <pyu@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2012-08-08 21:13:53 +00:00 • committed by David S. Miller
parent 79cda75a10
commit a399a80531
7 changed files with 22 additions and 19 deletions
Download patch file Download diff file Expand all files Collapse all files

9
net/ipv6/tcp_ipv6.c
View file

@ -1875,7 +1875,7 @@ static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
tp->write_seq-tp->snd_una,
(sp->sk_state == TCP_LISTEN) ? sp->sk_ack_backlog : (tp->rcv_nxt - tp->copied_seq),
timer_active,
jiffies_to_clock_t(timer_expires - jiffies),
jiffies_delta_to_clock_t(timer_expires - jiffies),
icsk->icsk_retransmits,
sock_i_uid(sp),
icsk->icsk_probes_out,
@ -1895,10 +1895,7 @@ static void get_timewait6_sock(struct seq_file *seq,
const struct in6_addr *dest, *src;
__u16 destp, srcp;
const struct inet6_timewait_sock *tw6 = inet6_twsk((struct sock *)tw);
int ttd = tw->tw_ttd - jiffies;
if (ttd < 0)
ttd = 0;
long delta = tw->tw_ttd - jiffies;
dest = &tw6->tw_v6_daddr;
src = &tw6->tw_v6_rcv_saddr;
@ -1914,7 +1911,7 @@ static void get_timewait6_sock(struct seq_file *seq,
dest->s6_addr32[0], dest->s6_addr32[1],
dest->s6_addr32[2], dest->s6_addr32[3], destp,
tw->tw_substate, 0, 0,
3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
atomic_read(&tw->tw_refcnt), tw);
}