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/include/linux/jiffies.h b/include/linux/jiffies.h
index 265e2c3..aded9b1 100644 (file)
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -303,7 +303,13 @@ extern void jiffies_to_timespec(const unsigned long jiffies,
 extern unsigned long timeval_to_jiffies(const struct timeval *value);
 extern void jiffies_to_timeval(const unsigned long jiffies,
                               struct timeval *value);
+
 extern clock_t jiffies_to_clock_t(unsigned long x);
+static inline clock_t jiffies_delta_to_clock_t(long delta)
+{
+       return jiffies_to_clock_t(max(0L, delta));
+}
+
 extern unsigned long clock_t_to_jiffies(unsigned long x);
 extern u64 jiffies_64_to_clock_t(u64 x);
 extern u64 nsec_to_clock_t(u64 x);

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index d21f323..9ce430b 100644 (file)
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -312,7 +312,7 @@ int br_fdb_fillbuf(struct net_bridge *br, void *buf,
 
                        fe->is_local = f->is_local;
                        if (!f->is_static)
-                               fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->updated);
+                               fe->ageing_timer_value = jiffies_delta_to_clock_t(jiffies - f->updated);
                        ++fe;
                        ++num;
                }

diff --git a/net/bridge/br_stp_timer.c b/net/bridge/br_stp_timer.c
index a6747e6..c3530a8 100644 (file)
--- a/net/bridge/br_stp_timer.c
+++ b/net/bridge/br_stp_timer.c
@@ -170,5 +170,5 @@ void br_stp_port_timer_init(struct net_bridge_port *p)
 unsigned long br_timer_value(const struct timer_list *timer)
 {
        return timer_pending(timer)
-               ? jiffies_to_clock_t(timer->expires - jiffies) : 0;
+               ? jiffies_delta_to_clock_t(timer->expires - jiffies) : 0;
 }

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 2c5a0a0..db037c9 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -618,7 +618,7 @@ int rtnl_put_cacheinfo(struct sk_buff *skb, struct dst_entry *dst, u32 id,
                       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,

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 6699f23..0b5580c 100644 (file)
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -2435,6 +2435,8 @@ static int igmp_mc_seq_show(struct seq_file *seq, void *v)
                struct ip_mc_list *im = (struct ip_mc_list *)v;
                struct igmp_mc_iter_state *state = igmp_mc_seq_private(seq);
                char   *querier;
+               long delta;
+
 #ifdef CONFIG_IP_MULTICAST
                querier = IGMP_V1_SEEN(state->in_dev) ? "V1" :
                          IGMP_V2_SEEN(state->in_dev) ? "V2" :
@@ -2448,11 +2450,12 @@ static int igmp_mc_seq_show(struct seq_file *seq, void *v)
                                   state->dev->ifindex, state->dev->name, state->in_dev->mc_count, querier);
                }
 
+               delta = im->timer.expires - jiffies;
                seq_printf(seq,
                           "\t\t\t\t%08X %5d %d:%08lX\t\t%d\n",
                           im->multiaddr, im->users,
-                          im->tm_running, im->tm_running ?
-                          jiffies_to_clock_t(im->timer.expires-jiffies) : 0,
+                          im->tm_running,
+                          im->tm_running ? jiffies_delta_to_clock_t(delta) : 0,
                           im->reporter);
        }
        return 0;

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 42b2a6a..c660d2c 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2385,7 +2385,7 @@ static void get_openreq4(const struct sock *sk, const struct request_sock *req,
                         struct seq_file *f, int i, int uid, int *len)
 {
        const struct inet_request_sock *ireq = inet_rsk(req);
-       int ttd = req->expires - jiffies;
+       long delta = req->expires - jiffies;
 
        seq_printf(f, "%4d: %08X:%04X %08X:%04X"
                " %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %pK%n",
@@ -2397,7 +2397,7 @@ static void get_openreq4(const struct sock *sk, const struct request_sock *req,
                TCP_SYN_RECV,
                0, 0, /* could print option size, but that is af dependent. */
                1,    /* timers active (only the expire timer) */
-               jiffies_to_clock_t(ttd),
+               jiffies_delta_to_clock_t(delta),
                req->retrans,
                uid,
                0,  /* non standard timer */
@@ -2448,7 +2448,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
                tp->write_seq - tp->snd_una,
                rx_queue,
                timer_active,
-               jiffies_to_clock_t(timer_expires - jiffies),
+               jiffies_delta_to_clock_t(timer_expires - jiffies),
                icsk->icsk_retransmits,
                sock_i_uid(sk),
                icsk->icsk_probes_out,
@@ -2467,10 +2467,7 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
 {
        __be32 dest, src;
        __u16 destp, srcp;
-       int ttd = tw->tw_ttd - jiffies;
-
-       if (ttd < 0)
-               ttd = 0;
+       long delta = tw->tw_ttd - jiffies;
 
        dest  = tw->tw_daddr;
        src   = tw->tw_rcv_saddr;
@@ -2480,7 +2477,7 @@ static void get_timewait4_sock(const struct inet_timewait_sock *tw,
        seq_printf(f, "%4d: %08X:%04X %08X:%04X"
                " %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK%n",
                i, src, srcp, dest, 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, len);
 }
 

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index c66b90f..aa41b0e 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -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);
 }