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      1 /*
      2   This file is part of drd, a thread error detector.
      3 
      4   Copyright (C) 2006-2015 Bart Van Assche <bvanassche (at) acm.org>.
      5 
      6   This program is free software; you can redistribute it and/or
      7   modify it under the terms of the GNU General Public License as
      8   published by the Free Software Foundation; either version 2 of the
      9   License, or (at your option) any later version.
     10 
     11   This program is distributed in the hope that it will be useful, but
     12   WITHOUT ANY WARRANTY; without even the implied warranty of
     13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     14   General Public License for more details.
     15 
     16   You should have received a copy of the GNU General Public License
     17   along with this program; if not, write to the Free Software
     18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
     19   02111-1307, USA.
     20 
     21   The GNU General Public License is contained in the file COPYING.
     22 */
     23 
     24 
     25 #include "drd_error.h"
     26 #include "drd_segment.h"
     27 #include "drd_thread.h"
     28 #include "pub_tool_basics.h"      // Addr, SizeT
     29 #include "pub_tool_libcassert.h"  // tl_assert()
     30 #include "pub_tool_libcbase.h"    // VG_(strlen)()
     31 #include "pub_tool_libcprint.h"   // VG_(printf)()
     32 #include "pub_tool_machine.h"     // VG_(get_SP)()
     33 #include "pub_tool_mallocfree.h"  // VG_(malloc)(), VG_(free)()
     34 #include "pub_tool_threadstate.h" // VG_INVALID_THREADID
     35 
     36 
     37 /* Global variables. */
     38 
     39 Segment* DRD_(g_sg_list);
     40 
     41 
     42 /* Local variables. */
     43 
     44 static ULong s_segment_merge_count;
     45 static ULong s_segments_created_count;
     46 static ULong s_segments_alive_count;
     47 static ULong s_max_segments_alive_count;
     48 static Bool s_trace_segment;
     49 
     50 
     51 /* Function definitions. */
     52 
     53 /**
     54  * Initialize the memory 'sg' points at.
     55  *
     56  * @note The creator and created thread ID's may be equal.
     57  * @note This function copies the vector clock of thread 'creator', a technique
     58  *   also known as clock snooping. This will only work reliably if the thread
     59  *   that called pthread_create() waits until the created thread has copied
     60  *   the vector clock.
     61  */
     62 static void sg_init(Segment* const sg,
     63                     const DrdThreadId creator,
     64                     const DrdThreadId created)
     65 {
     66    Segment* creator_sg;
     67    ThreadId vg_created = DRD_(DrdThreadIdToVgThreadId)(created);
     68 
     69    tl_assert(sg);
     70    tl_assert(creator == DRD_INVALID_THREADID
     71              || DRD_(IsValidDrdThreadId)(creator));
     72 
     73    creator_sg = (creator != DRD_INVALID_THREADID
     74                  ? DRD_(thread_get_segment)(creator) : 0);
     75 
     76    sg->g_next = NULL;
     77    sg->g_prev = NULL;
     78    sg->thr_next = NULL;
     79    sg->thr_prev = NULL;
     80    sg->tid = created;
     81    sg->refcnt = 1;
     82 
     83    if (vg_created != VG_INVALID_THREADID && VG_(get_SP)(vg_created) != 0)
     84       sg->stacktrace = VG_(record_ExeContext)(vg_created, 0);
     85    else
     86       sg->stacktrace = 0;
     87 
     88    if (creator_sg)
     89       DRD_(vc_copy)(&sg->vc, &creator_sg->vc);
     90    else
     91       DRD_(vc_init)(&sg->vc, 0, 0);
     92    DRD_(vc_increment)(&sg->vc, created);
     93    DRD_(bm_init)(&sg->bm);
     94 
     95    if (s_trace_segment)
     96    {
     97       HChar* vc;
     98 
     99       vc = DRD_(vc_aprint)(&sg->vc);
    100       VG_(message)(Vg_DebugMsg, "New segment for thread %u with vc %s\n",
    101                    created, vc);
    102       VG_(free)(vc);
    103    }
    104 }
    105 
    106 /** Deallocate the memory that was allocated by sg_init(). */
    107 static void DRD_(sg_cleanup)(Segment* const sg)
    108 {
    109    tl_assert(sg);
    110    tl_assert(sg->refcnt == 0);
    111 
    112    DRD_(vc_cleanup)(&sg->vc);
    113    DRD_(bm_cleanup)(&sg->bm);
    114 }
    115 
    116 /** Allocate and initialize a new segment. */
    117 Segment* DRD_(sg_new)(const DrdThreadId creator, const DrdThreadId created)
    118 {
    119    Segment* sg;
    120 
    121    s_segments_created_count++;
    122    s_segments_alive_count++;
    123    if (s_max_segments_alive_count < s_segments_alive_count)
    124       s_max_segments_alive_count = s_segments_alive_count;
    125 
    126    sg = VG_(malloc)("drd.segment.sn.1", sizeof(*sg));
    127    sg_init(sg, creator, created);
    128    if (DRD_(g_sg_list)) {
    129       DRD_(g_sg_list)->g_prev = sg;
    130       sg->g_next = DRD_(g_sg_list);
    131    }
    132    DRD_(g_sg_list) = sg;
    133    return sg;
    134 }
    135 
    136 static void DRD_(sg_delete)(Segment* const sg)
    137 {
    138    if (DRD_(sg_get_trace)())
    139    {
    140       HChar* vc;
    141 
    142       vc = DRD_(vc_aprint)(&sg->vc);
    143       VG_(message)(Vg_DebugMsg, "Discarding the segment with vector clock %s\n",
    144                    vc);
    145       VG_(free)(vc);
    146    }
    147 
    148    s_segments_alive_count--;
    149 
    150    tl_assert(sg);
    151    if (sg->g_next)
    152       sg->g_next->g_prev = sg->g_prev;
    153    if (sg->g_prev)
    154       sg->g_prev->g_next = sg->g_next;
    155    else
    156       DRD_(g_sg_list) = sg->g_next;
    157    DRD_(sg_cleanup)(sg);
    158    VG_(free)(sg);
    159 }
    160 
    161 /** Increment the reference count of the specified segment. */
    162 Segment* DRD_(sg_get)(Segment* const sg)
    163 {
    164    tl_assert(sg);
    165 
    166    sg->refcnt++;
    167    return sg;
    168 }
    169 
    170 /**
    171  * Decrement the reference count of the specified segment and deallocate the
    172  * segment if the reference count became zero.
    173  */
    174 void DRD_(sg_put)(Segment* const sg)
    175 {
    176    if (sg == 0)
    177       return;
    178 
    179    if (s_trace_segment)
    180    {
    181       HChar* vc;
    182 
    183       vc = DRD_(vc_aprint)(&sg->vc);
    184       VG_(message)(Vg_DebugMsg,
    185                    "Decrementing segment reference count %d -> %d with vc %s\n",
    186                    sg->refcnt, sg->refcnt - 1, vc);
    187       VG_(free)(vc);
    188    }
    189 
    190    tl_assert(sg->refcnt >= 1);
    191 
    192    if (--sg->refcnt == 0)
    193    {
    194       DRD_(sg_delete)(sg);
    195    }
    196 }
    197 
    198 /** Merge sg1 and sg2 into sg1. */
    199 void DRD_(sg_merge)(Segment* const sg1, Segment* const sg2)
    200 {
    201    tl_assert(sg1);
    202    tl_assert(sg1->refcnt == 1);
    203    tl_assert(sg2);
    204    tl_assert(sg2->refcnt == 1);
    205 
    206    if (s_trace_segment)
    207    {
    208       HChar *vc1, *vc2;
    209 
    210       vc1 = DRD_(vc_aprint)(&sg1->vc);
    211       vc2 = DRD_(vc_aprint)(&sg2->vc);
    212 
    213       VG_(message)(Vg_DebugMsg,
    214 		   "Merging segments with vector clocks %s and %s\n", vc1, vc2);
    215       VG_(free)(vc1);
    216       VG_(free)(vc2);
    217    }
    218 
    219    s_segment_merge_count++;
    220 
    221    // Keep sg1->stacktrace.
    222    // Keep sg1->vc.
    223    // Merge sg2->bm into sg1->bm.
    224    DRD_(bm_merge2)(&sg1->bm, &sg2->bm);
    225 }
    226 
    227 /** Print the vector clock and the bitmap of the specified segment. */
    228 void DRD_(sg_print)(Segment* const sg)
    229 {
    230    tl_assert(sg);
    231    VG_(printf)("vc: ");
    232    DRD_(vc_print)(&sg->vc);
    233    VG_(printf)("\n");
    234    DRD_(bm_print)(&sg->bm);
    235 }
    236 
    237 /** Query whether segment tracing has been enabled. */
    238 Bool DRD_(sg_get_trace)(void)
    239 {
    240    return s_trace_segment;
    241 }
    242 
    243 /** Enable or disable segment tracing. */
    244 void DRD_(sg_set_trace)(Bool const trace_segment)
    245 {
    246    tl_assert(trace_segment == False || trace_segment == True);
    247    s_trace_segment = trace_segment;
    248 }
    249 
    250 ULong DRD_(sg_get_segments_created_count)(void)
    251 {
    252    return s_segments_created_count;
    253 }
    254 
    255 ULong DRD_(sg_get_segments_alive_count)(void)
    256 {
    257    return s_segments_alive_count;
    258 }
    259 
    260 ULong DRD_(sg_get_max_segments_alive_count)(void)
    261 {
    262    return s_max_segments_alive_count;
    263 }
    264 
    265 ULong DRD_(sg_get_segment_merge_count)(void)
    266 {
    267    return s_segment_merge_count;
    268 }
    269