diff options
| -rw-r--r-- | net/dccp/ccids/lib/tfrc_equation.c | 33 |
1 files changed, 19 insertions, 14 deletions
diff --git a/net/dccp/ccids/lib/tfrc_equation.c b/net/dccp/ccids/lib/tfrc_equation.c index 78bdf3489162..ef3233d45a61 100644 --- a/net/dccp/ccids/lib/tfrc_equation.c +++ b/net/dccp/ccids/lib/tfrc_equation.c @@ -608,22 +608,19 @@ u32 tfrc_calc_x(u16 s, u32 R, u32 p) u32 f; u64 tmp1, tmp2; + /* check against invalid parameters and divide-by-zero */ + BUG_ON(p > 1000000); /* p must not exceed 100% */ + BUG_ON(p == 0); /* f(0) = 0, divide by zero */ + if (R == 0) { /* possible divide by zero */ + DCCP_CRIT("WARNING: RTT is 0, returning maximum X_calc."); + return ~0U; + } + if (p < TFRC_CALC_X_SPLIT) /* 0 <= p < 0.05 */ index = (p / (TFRC_CALC_X_SPLIT / TFRC_CALC_X_ARRSIZE)) - 1; else /* 0.05 <= p <= 1.00 */ index = (p / (1000000 / TFRC_CALC_X_ARRSIZE)) - 1; - if (index < 0) - /* p should be 0 unless there is a bug in my code */ - index = 0; - - if (R == 0) { - DCCP_WARN("RTT==0, setting to 1\n"); - R = 1; /* RTT can't be zero or else divide by zero */ - } - - BUG_ON(index >= TFRC_CALC_X_ARRSIZE); - if (p >= TFRC_CALC_X_SPLIT) f = tfrc_calc_x_lookup[index][0]; else @@ -653,13 +650,21 @@ u32 tfrc_calc_x_reverse_lookup(u32 fvalue) int ctr = 0; int small; - if (fvalue < tfrc_calc_x_lookup[0][1]) + if (fvalue == 0) /* f(p) = 0 whenever p = 0 */ return 0; + /* Error cases. */ + if (fvalue < tfrc_calc_x_lookup[0][1]) { + DCCP_WARN("fvalue %d smaller than resolution\n", fvalue); + return tfrc_calc_x_lookup[0][1]; + } + if (fvalue > tfrc_calc_x_lookup[TFRC_CALC_X_ARRSIZE - 1][0]) { + DCCP_WARN("fvalue %d exceeds bounds!\n", fvalue); + return 1000000; + } + if (fvalue <= tfrc_calc_x_lookup[TFRC_CALC_X_ARRSIZE - 1][1]) small = 1; - else if (fvalue > tfrc_calc_x_lookup[TFRC_CALC_X_ARRSIZE - 1][0]) - return 1000000; else small = 0; |