[NETFILTER]: x_tables: remove unused argument to target functions

[safe/jmp/linux-2.6] / net / ipv4 / tcp_cubic.c

diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
index 44fd408..2be2798 100644 (file)
--- a/net/ipv4/tcp_cubic.c
+++ b/net/ipv4/tcp_cubic.c
@@ -12,7 +12,6 @@
  * this behaves the same as the original Reno.
  */
 
-#include <linux/config.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <net/tcp.h>
@@ -52,6 +51,7 @@ MODULE_PARM_DESC(bic_scale, "scale (scaled by 1024) value for bic function (bic_
 module_param(tcp_friendliness, int, 0644);
 MODULE_PARM_DESC(tcp_friendliness, "turn on/off tcp friendliness");
 
+#include <asm/div64.h>
 
 /* BIC TCP Parameters */
 struct bictcp {
@@ -93,67 +93,51 @@ static void bictcp_init(struct sock *sk)
                tcp_sk(sk)->snd_ssthresh = initial_ssthresh;
 }
 
-/* 65536 times the cubic root */
-static const u64 cubic_table[8]
-       = {0, 65536, 82570, 94519, 104030, 112063, 119087, 125367};
+/* 64bit divisor, dividend and result. dynamic precision */
+static inline u_int64_t div64_64(u_int64_t dividend, u_int64_t divisor)
+{
+       u_int32_t d = divisor;
+
+       if (divisor > 0xffffffffULL) {
+               unsigned int shift = fls(divisor >> 32);
+
+               d = divisor >> shift;
+               dividend >>= shift;
+       }
+
+       /* avoid 64 bit division if possible */
+       if (dividend >> 32)
+               do_div(dividend, d);
+       else
+               dividend = (uint32_t) dividend / d;
+
+       return dividend;
+}
 
 /*
- * calculate the cubic root of x
- * the basic idea is that x can be expressed as i*8^j
- * so cubic_root(x) = cubic_root(i)*2^j
- *  in the following code, x is i, and y is 2^j
- *  because of integer calculation, there are errors in calculation
- *  so finally use binary search to find out the exact solution
+ * calculate the cubic root of x using Newton-Raphson
  */
-static u32 cubic_root(u64 x)
+static u32 cubic_root(u64 a)
 {
-        u64 y, app, target, start, end, mid, start_diff, end_diff;
-
-        if (x == 0)
-                return 0;
-
-        target = x;
+       u32 x, x1;
 
-        /* first estimate lower and upper bound */
-        y = 1;
-        while (x >= 8){
-                x = (x >> 3);
-                y = (y << 1);
-        }
-        start = (y*cubic_table[x])>>16;
-        if (x==7)
-                end = (y<<1);
-        else
-                end = (y*cubic_table[x+1]+65535)>>16;
-
-        /* binary search for more accurate one */
-        while (start < end-1) {
-                mid = (start+end) >> 1;
-                app = mid*mid*mid;
-                if (app < target)
-                        start = mid;
-                else if (app > target)
-                        end = mid;
-                else
-                        return mid;
-        }
+       /* Initial estimate is based on:
+        * cbrt(x) = exp(log(x) / 3)
+        */
+       x = 1u << (fls64(a)/3);
 
-        /* find the most accurate one from start and end */
-        app = start*start*start;
-        if (app < target)
-                start_diff = target - app;
-        else
-                start_diff = app - target;
-        app = end*end*end;
-        if (app < target)
-                end_diff = target - app;
-        else
-                end_diff = app - target;
+       /*
+        * Iteration based on:
+        *                         2
+        * x    = ( 2 * x  +  a / x  ) / 3
+        *  k+1          k         k
+        */
+       do {
+               x1 = x;
+               x = (2 * x + (uint32_t) div64_64(a, x*x)) / 3;
+       } while (abs(x1 - x) > 1);
 
-        if (start_diff < end_diff)
-                return (u32)start;
-        else
-                return (u32)end;
+       return x;
 }
 
 /*
@@ -340,11 +324,6 @@ static u32 bictcp_undo_cwnd(struct sock *sk)
        return max(tcp_sk(sk)->snd_cwnd, ca->last_max_cwnd);
 }
 
-static u32 bictcp_min_cwnd(struct sock *sk)
-{
-       return tcp_sk(sk)->snd_ssthresh;
-}
-
 static void bictcp_state(struct sock *sk, u8 new_state)
 {
        if (new_state == TCP_CA_Loss)
@@ -372,7 +351,6 @@ static struct tcp_congestion_ops cubictcp = {
        .cong_avoid     = bictcp_cong_avoid,
        .set_state      = bictcp_state,
        .undo_cwnd      = bictcp_undo_cwnd,
-       .min_cwnd       = bictcp_min_cwnd,
        .pkts_acked     = bictcp_acked,
        .owner          = THIS_MODULE,
        .name           = "cubic",