[tor-bugs] #24633 [Core Tor/Tor]: to->pending->tqh_last is 0xFFFFFFFFFFFFFFFF。

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#24633: to->pending->tqh_last is 0xFFFFFFFFFFFFFFFF。
-------------------------------------------------+-------------------------
 Reporter:  sx5486510                            |          Owner:  nickm
     Type:  defect                               |         Status:
                                                 |  accepted
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.2.x-final
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  0.3.2.1-alpha
 Severity:  Normal                               |     Resolution:
 Keywords:  msvc 029-backport 030-backport       |  Actual Points:
  031-backport                                   |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by sx5486510):

 I modify the function like this:
 src/ext/timeouts/timeout-bitops.c

 ...

 #define LT(n) n, n, n, n, n, n, n, n, n, n, n, n, n, n, n, n
 static const char logTable[256] = {
         0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
         LT(5), LT(6), LT(6), LT(7), LT(7), LT(7), LT(7),
         LT(8), LT(8), LT(8), LT(8), LT(8), LT(8), LT(8), LT(8)
 };
 #undef LT

 ...

 static __inline int clz32(unsigned long val)
 {
         unsigned int t;

         if ((t = val >> 24)) {
                 return 8 - logTable[t];
         }
         else if ((t = val >> 16)) {
                 return 16 - logTable[t];
         }
         else if ((t = val >> 8)) {
                 return 24 - logTable[t];
         }
         else {
                 return 32 - logTable[val];
         }
         DWORD zeros = 0;
         _BitScanReverse(&zeros, val);
         return zeros;
 }
 ...

 static __inline int clz64(uint64_t val)
 {
         unsigned __int64 t;

         if ((t = val >> 56)) {
                 return 8 - logTable[t];
         }
         else if ((t = val >> 48)) {
                 return 16 - logTable[t];
         }
         else if ((t = val >> 40)) {
                 return 24 - logTable[t];
         }
         else if ((t = val >> 32)) {
                 return 32 - logTable[t];
         }
         else if ((t = val >> 24)) {
                 return 40 - logTable[t];
         }
         else if ((t = val >> 16)) {
                 return 48 - logTable[t];
         }
         else if ((t = val >> 8)) {
                 return 56 - logTable[t];
         }
         else {
                 return 64 - logTable[val];
         }

         DWORD zeros = 0;
         _BitScanReverse64(&zeros, val);
         return zeros;
 }
 ...

 The code is copy from here: https://fossies.org/linux/Pike/src/bitvector.h

 The test is pass, but i'm not sure the code will return correct result in
 any case.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24633#comment:6>
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