1 files changed, 37 insertions, 28 deletions

diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c
index 63318b6e9d51..1020eb48d8d1 100644
--- a/net/ipv4/tcp_htcp.c
+++ b/net/ipv4/tcp_htcp.c
@@ -10,22 +10,23 @@
 #include <linux/module.h>
 #include <net/tcp.h>
 
-#define ALPHA_BASE      (1<<7)  /* 1.0 with shift << 7 */
-#define BETA_MIN        (1<<6)  /* 0.5 with shift << 7 */
+#define ALPHA_BASE      (1<<7)  /* 1.0 with shift << 7 */
+#define BETA_MIN        (1<<6)  /* 0.5 with shift << 7 */
 #define BETA_MAX        102     /* 0.8 with shift << 7 */
 
-static int use_rtt_scaling = 1;
+static int use_rtt_scaling __read_mostly = 1;
 module_param(use_rtt_scaling, int, 0644);
 MODULE_PARM_DESC(use_rtt_scaling, "turn on/off RTT scaling");
 
-static int use_bandwidth_switch = 1;
+static int use_bandwidth_switch __read_mostly = 1;
 module_param(use_bandwidth_switch, int, 0644);
 MODULE_PARM_DESC(use_bandwidth_switch, "turn on/off bandwidth switcher");
 
 struct htcp {
         u32     alpha;          /* Fixed point arith, << 7 */
         u8      beta;           /* Fixed point arith, << 7 */
-        u8      modeswitch;     /* Delay modeswitch until we had at least one congestion event */
+        u8      modeswitch;     /* Delay modeswitch
+                                   until we had at least one congestion event */
         u16     pkts_acked;
         u32     packetcount;
         u32     minRTT;
@@ -44,14 +45,14 @@ struct htcp {
         u32     lasttime;
 };
 
-static inline u32 htcp_cong_time(struct htcp *ca)
+static inline u32 htcp_cong_time(const struct htcp *ca)
 {
         return jiffies - ca->last_cong;
 }
 
-static inline u32 htcp_ccount(struct htcp *ca)
+static inline u32 htcp_ccount(const struct htcp *ca)
 {
-        return htcp_cong_time(ca)/ca->minRTT;
+        return htcp_cong_time(ca) / ca->minRTT;
 }
 
 static inline void htcp_reset(struct htcp *ca)
@@ -67,10 +68,12 @@ static u32 htcp_cwnd_undo(struct sock *sk)
 {
         const struct tcp_sock *tp = tcp_sk(sk);
         struct htcp *ca = inet_csk_ca(sk);
+
         ca->last_cong = ca->undo_last_cong;
         ca->maxRTT = ca->undo_maxRTT;
         ca->old_maxB = ca->undo_old_maxB;
-        return max(tp->snd_cwnd, (tp->snd_ssthresh<<7)/ca->beta);
+
+        return max(tp->snd_cwnd, (tp->snd_ssthresh << 7) / ca->beta);
 }
 
 static inline void measure_rtt(struct sock *sk)
@@ -78,17 +81,19 @@ static inline void measure_rtt(struct sock *sk)
         const struct inet_connection_sock *icsk = inet_csk(sk);
         const struct tcp_sock *tp = tcp_sk(sk);
         struct htcp *ca = inet_csk_ca(sk);
-        u32 srtt = tp->srtt>>3;
+        u32 srtt = tp->srtt >> 3;
 
         /* keep track of minimum RTT seen so far, minRTT is zero at first */
         if (ca->minRTT > srtt || !ca->minRTT)
                 ca->minRTT = srtt;
 
         /* max RTT */
-        if (icsk->icsk_ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && htcp_ccount(ca) > 3) {
+        if (icsk->icsk_ca_state == TCP_CA_Open
+            && tp->snd_ssthresh < 0xFFFF && htcp_ccount(ca) > 3) {
                 if (ca->maxRTT < ca->minRTT)
                         ca->maxRTT = ca->minRTT;
-                if (ca->maxRTT < srtt && srtt <= ca->maxRTT+msecs_to_jiffies(20))
+                if (ca->maxRTT < srtt
+                    && srtt <= ca->maxRTT + msecs_to_jiffies(20))
                         ca->maxRTT = srtt;
         }
 }
@@ -116,15 +121,16 @@ static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked)
 
         ca->packetcount += pkts_acked;
 
-        if (ca->packetcount >= tp->snd_cwnd - (ca->alpha>>7? : 1)
-                        && now - ca->lasttime >= ca->minRTT
-                        && ca->minRTT > 0) {
-                __u32 cur_Bi = ca->packetcount*HZ/(now - ca->lasttime);
+        if (ca->packetcount >= tp->snd_cwnd - (ca->alpha >> 7 ? : 1)
+            && now - ca->lasttime >= ca->minRTT
+            && ca->minRTT > 0) {
+                __u32 cur_Bi = ca->packetcount * HZ / (now - ca->lasttime);
+
                 if (htcp_ccount(ca) <= 3) {
                         /* just after backoff */
                         ca->minB = ca->maxB = ca->Bi = cur_Bi;
                 } else {
-                        ca->Bi = (3*ca->Bi + cur_Bi)/4;
+                        ca->Bi = (3 * ca->Bi + cur_Bi) / 4;
                         if (ca->Bi > ca->maxB)
                                 ca->maxB = ca->Bi;
                         if (ca->minB > ca->maxB)
@@ -142,7 +148,7 @@ static inline void htcp_beta_update(struct htcp *ca, u32 minRTT, u32 maxRTT)
                 u32 old_maxB = ca->old_maxB;
                 ca->old_maxB = ca->maxB;
 
-                if (!between(5*maxB, 4*old_maxB, 6*old_maxB)) {
+                if (!between(5 * maxB, 4 * old_maxB, 6 * old_maxB)) {
                         ca->beta = BETA_MIN;
                         ca->modeswitch = 0;
                         return;
@@ -150,7 +156,7 @@ static inline void htcp_beta_update(struct htcp *ca, u32 minRTT, u32 maxRTT)
         }
 
         if (ca->modeswitch && minRTT > msecs_to_jiffies(10) && maxRTT) {
-                ca->beta = (minRTT<<7)/maxRTT;
+                ca->beta = (minRTT << 7) / maxRTT;
                 if (ca->beta < BETA_MIN)
                         ca->beta = BETA_MIN;
                 else if (ca->beta > BETA_MAX)
@@ -169,23 +175,26 @@ static inline void htcp_alpha_update(struct htcp *ca)
 
         if (diff > HZ) {
                 diff -= HZ;
-                factor = 1+ ( 10*diff + ((diff/2)*(diff/2)/HZ) )/HZ;
+                factor = 1 + (10 * diff + ((diff / 2) * (diff / 2) / HZ)) / HZ;
         }
 
         if (use_rtt_scaling && minRTT) {
-                u32 scale = (HZ<<3)/(10*minRTT);
-                scale = min(max(scale, 1U<<2), 10U<<3); /* clamping ratio to interval [0.5,10]<<3 */
-                factor = (factor<<3)/scale;
+                u32 scale = (HZ << 3) / (10 * minRTT);
+
+                /* clamping ratio to interval [0.5,10]<<3 */
+                scale = min(max(scale, 1U << 2), 10U << 3);
+                factor = (factor << 3) / scale;
                 if (!factor)
                         factor = 1;
         }
 
-        ca->alpha = 2*factor*((1<<7)-ca->beta);
+        ca->alpha = 2 * factor * ((1 << 7) - ca->beta);
         if (!ca->alpha)
                 ca->alpha = ALPHA_BASE;
 }
 
-/* After we have the rtt data to calculate beta, we'd still prefer to wait one
+/*
+ * After we have the rtt data to calculate beta, we'd still prefer to wait one
  * rtt before we adjust our beta to ensure we are working from a consistent
  * data.
  *
@@ -202,15 +211,16 @@ static void htcp_param_update(struct sock *sk)
         htcp_beta_update(ca, minRTT, maxRTT);
         htcp_alpha_update(ca);
 
-        /* add slowly fading memory for maxRTT to accommodate routing changes etc */
+        /* add slowly fading memory for maxRTT to accommodate routing changes */
         if (minRTT > 0 && maxRTT > minRTT)
-                ca->maxRTT = minRTT + ((maxRTT-minRTT)*95)/100;
+                ca->maxRTT = minRTT + ((maxRTT - minRTT) * 95) / 100;
 }
 
 static u32 htcp_recalc_ssthresh(struct sock *sk)
 {
         const struct tcp_sock *tp = tcp_sk(sk);
         const struct htcp *ca = inet_csk_ca(sk);
+
         htcp_param_update(sk);
         return max((tp->snd_cwnd * ca->beta) >> 7, 2U);
 }
@@ -227,7 +237,6 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt,
         if (tp->snd_cwnd <= tp->snd_ssthresh)
                 tcp_slow_start(tp);
         else {
-
                 measure_rtt(sk);
 
                 /* In dangerous area, increase slowly.