time: jiffies_delta_to_clock_t() helper to the rescue
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 cbbc719fccdb8cb (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>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 2c5a0a0..db037c9 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -618,7 +618,7 @@
long expires, u32 error)
{
struct rta_cacheinfo ci = {
- .rta_lastuse = jiffies_to_clock_t(jiffies - dst->lastuse),
+ .rta_lastuse = jiffies_delta_to_clock_t(jiffies - dst->lastuse),
.rta_used = dst->__use,
.rta_clntref = atomic_read(&(dst->__refcnt)),
.rta_error = error,
