drd/drd_mutex.c

/*
  This file is part of drd, a thread error detector.

  Copyright (C) 2006-2009 Bart Van Assche <bart.vanassche@gmail.com>.

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License as
  published by the Free Software Foundation; either version 2 of the
  License, or (at your option) any later version.

  This program is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  02111-1307, USA.

  The GNU General Public License is contained in the file COPYING.
*/


#include "drd_basics.h"
#include "drd_clientobj.h"
#include "drd_error.h"
#include "drd_mutex.h"
#include "pub_tool_vki.h"
#include "pub_tool_errormgr.h"    // VG_(maybe_record_error)()
#include "pub_tool_libcassert.h"  // tl_assert()
#include "pub_tool_libcbase.h"    // VG_(strlen)
#include "pub_tool_libcprint.h"   // VG_(message)()
#include "pub_tool_libcproc.h"    // VG_(read_millisecond_timer)()
#include "pub_tool_machine.h"     // VG_(get_IP)()
#include "pub_tool_threadstate.h" // VG_(get_running_tid)()


/* Local functions. */

static void DRD_(mutex_cleanup)(struct mutex_info* p);
static Bool DRD_(mutex_is_locked)(struct mutex_info* const p);


/* Local variables. */

static Bool DRD_(s_trace_mutex);
static ULong DRD_(s_mutex_lock_count);
static ULong DRD_(s_mutex_segment_creation_count);
static UInt DRD_(s_mutex_lock_threshold_ms) = 1000 * 1000;


/* Function definitions. */

void DRD_(mutex_set_trace)(const Bool trace_mutex)
{
  tl_assert(!! trace_mutex == trace_mutex);
  DRD_(s_trace_mutex) = trace_mutex;
}

void DRD_(mutex_set_lock_threshold)(const UInt lock_threshold_ms)
{
  DRD_(s_mutex_lock_threshold_ms) = lock_threshold_ms;
}

static
void DRD_(mutex_initialize)(struct mutex_info* const p,
                            const Addr mutex, const MutexT mutex_type)
{
  tl_assert(mutex);
  tl_assert(mutex_type != mutex_type_unknown);
  tl_assert(p->a1 == mutex);

  p->cleanup             = (void(*)(DrdClientobj*))&(DRD_(mutex_cleanup));
  p->mutex_type          = mutex_type;
  p->recursion_count     = 0;
  p->owner               = DRD_INVALID_THREADID;
  p->last_locked_segment = 0;
  p->acquiry_time_ms     = 0;
  p->acquired_at         = 0;
}

/** Deallocate the memory that was allocated by mutex_initialize(). */
static void DRD_(mutex_cleanup)(struct mutex_info* p)
{
  tl_assert(p);

  if (DRD_(s_trace_mutex))
  {
    VG_(message)(Vg_UserMsg,
                 "[%d/%d] mutex_destroy   %s 0x%lx rc %d owner %d",
                 VG_(get_running_tid)(),
                 DRD_(thread_get_running_tid)(),
                 DRD_(mutex_get_typename)(p),
                 p->a1,
                 p ? p->recursion_count : -1,
                 p ? p->owner : DRD_INVALID_THREADID);
  }

  if (DRD_(mutex_is_locked)(p))
  {
    MutexErrInfo MEI = { p->a1, p->recursion_count, p->owner };
    VG_(maybe_record_error)(VG_(get_running_tid)(),
                            MutexErr,
                            VG_(get_IP)(VG_(get_running_tid)()),
                            "Destroying locked mutex",
                            &MEI);
  }

  DRD_(sg_put)(p->last_locked_segment);
  p->last_locked_segment = 0;
}

/** Let Valgrind report that there is no mutex object at address 'mutex'. */
void DRD_(not_a_mutex)(const Addr mutex)
{
  MutexErrInfo MEI = { mutex, -1, DRD_INVALID_THREADID };
  VG_(maybe_record_error)(VG_(get_running_tid)(),
                          MutexErr,
                          VG_(get_IP)(VG_(get_running_tid)()),
                          "Not a mutex",
                          &MEI);
}

static
struct mutex_info*
DRD_(mutex_get_or_allocate)(const Addr mutex, const MutexT mutex_type)
{
  struct mutex_info* p;

  tl_assert(offsetof(DrdClientobj, mutex) == 0);
  p = &(DRD_(clientobj_get)(mutex, ClientMutex)->mutex);
  if (p)
  {
    return p;
  }

  if (DRD_(clientobj_present)(mutex, mutex + 1))
  {
    DRD_(not_a_mutex)(mutex);
    return 0;
  }

  tl_assert(mutex_type != mutex_type_unknown);

  p = &(DRD_(clientobj_add)(mutex, ClientMutex)->mutex);
  DRD_(mutex_initialize)(p, mutex, mutex_type);
  return p;
}

struct mutex_info* DRD_(mutex_get)(const Addr mutex)
{
  tl_assert(offsetof(DrdClientobj, mutex) == 0);
  return &(DRD_(clientobj_get)(mutex, ClientMutex)->mutex);
}

/** Called before pthread_mutex_init(). */
struct mutex_info*
DRD_(mutex_init)(const Addr mutex, const MutexT mutex_type)
{
  struct mutex_info* p;

  tl_assert(mutex_type != mutex_type_unknown);

  if (DRD_(s_trace_mutex))
  {
    VG_(message)(Vg_UserMsg,
                 "[%d/%d] mutex_init      %s 0x%lx",
                 VG_(get_running_tid)(),
                 DRD_(thread_get_running_tid)(),
                 DRD_(mutex_type_name)(mutex_type),
                 mutex);
  }

  if (mutex_type == mutex_type_invalid_mutex)
  {
    DRD_(not_a_mutex)(mutex);
    return 0;
  }

  p = DRD_(mutex_get)(mutex);
  if (p)
  {
    const ThreadId vg_tid = VG_(get_running_tid)();
    MutexErrInfo MEI
      = { p->a1, p->recursion_count, p->owner };
    VG_(maybe_record_error)(vg_tid,
                            MutexErr,
                            VG_(get_IP)(vg_tid),
                            "Mutex reinitialization",
                            &MEI);
    return p;
  }
  p = DRD_(mutex_get_or_allocate)(mutex, mutex_type);

  return p;
}

/** Called after pthread_mutex_destroy(). */
void DRD_(mutex_post_destroy)(const Addr mutex)
{
  struct mutex_info* p;

  p = DRD_(mutex_get)(mutex);
  if (p == 0)
  {
    DRD_(not_a_mutex)(mutex);
    return;
  }

  DRD_(clientobj_remove)(mutex, ClientMutex);
}

/** Called before pthread_mutex_lock() is invoked. If a data structure for
 *  the client-side object was not yet created, do this now. Also check whether
 *  an attempt is made to lock recursively a synchronization object that must
 *  not be locked recursively.
 */
void DRD_(mutex_pre_lock)(const Addr mutex, MutexT mutex_type,
                          const Bool trylock)
{
  struct mutex_info* p;

  p = DRD_(mutex_get_or_allocate)(mutex, mutex_type);
  if (mutex_type == mutex_type_unknown)
    mutex_type = p->mutex_type;

  if (DRD_(s_trace_mutex))
  {
    VG_(message)(Vg_UserMsg,
                 "[%d/%d] %s %s 0x%lx rc %d owner %d",
                 VG_(get_running_tid)(),
                 DRD_(thread_get_running_tid)(),
                 trylock ? "pre_mutex_lock " : "mutex_trylock  ",
                 p ? DRD_(mutex_get_typename)(p) : "(?)",
                 mutex,
                 p ? p->recursion_count : -1,
                 p ? p->owner : DRD_INVALID_THREADID);
  }

  if (p == 0)
  {
    DRD_(not_a_mutex)(mutex);
    return;
  }

  tl_assert(p);

  if (mutex_type == mutex_type_invalid_mutex)
  {
    DRD_(not_a_mutex)(mutex);
    return;
  }

  if (! trylock
      && p->owner == DRD_(thread_get_running_tid)()
      && p->recursion_count >= 1
      && mutex_type != mutex_type_recursive_mutex)
  {
    MutexErrInfo MEI = { p->a1, p->recursion_count, p->owner };
    VG_(maybe_record_error)(VG_(get_running_tid)(),
                            MutexErr,
                            VG_(get_IP)(VG_(get_running_tid)()),
                            "Recursive locking not allowed",
                            &MEI);
  }
}

/**
 * Update mutex_info state when locking the pthread_mutex_t mutex.
 * Note: this function must be called after pthread_mutex_lock() has been
 * called, or a race condition is triggered !
 */
void DRD_(mutex_post_lock)(const Addr mutex, const Bool took_lock,
                           const Bool post_cond_wait)
{
  const DrdThreadId drd_tid = DRD_(thread_get_running_tid)();
  struct mutex_info* p;

  p = DRD_(mutex_get)(mutex);

  if (DRD_(s_trace_mutex))
  {
    VG_(message)(Vg_UserMsg,
                 "[%d/%d] %s %s 0x%lx rc %d owner %d%s",
                 VG_(get_running_tid)(),
                 drd_tid,
                 post_cond_wait ? "cond_post_wait " : "post_mutex_lock",
                 p ? DRD_(mutex_get_typename)(p) : "(?)",
                 mutex,
                 p ? p->recursion_count : 0,
                 p ? p->owner : VG_INVALID_THREADID,
                 took_lock ? "" : " (locking failed)");
  }

  if (! p || ! took_lock)
    return;

  if (p->recursion_count == 0)
  {
    const DrdThreadId last_owner = p->owner;

    if (last_owner != drd_tid && last_owner != DRD_INVALID_THREADID)
    {
      tl_assert(p->last_locked_segment);
      DRD_(thread_combine_vc2)(drd_tid, &p->last_locked_segment->vc);
    }
    DRD_(thread_new_segment)(drd_tid);
    DRD_(s_mutex_segment_creation_count)++;

    p->owner           = drd_tid;
    p->acquiry_time_ms = VG_(read_millisecond_timer)();
    p->acquired_at     = VG_(record_ExeContext)(VG_(get_running_tid)(), 0);
    DRD_(s_mutex_lock_count)++;
  }
  else if (p->owner != drd_tid)
  {
    VG_(message)(Vg_UserMsg,
                 "The impossible happened: mutex 0x%lx is locked"
                 " simultaneously by two threads (recursion count %d,"
                 " owners %d and %d) !",
                 p->a1, p->recursion_count, p->owner, drd_tid);
    p->owner = drd_tid;
  }
  p->recursion_count++;
}

/**
 * Update mutex_info state when unlocking the pthread_mutex_t mutex.
 *
 * @param[in] mutex      Address of the client mutex.
 * @param[in] mutex_type Mutex type.
 *
 * @return New value of the mutex recursion count.
 *
 * @note This function must be called before pthread_mutex_unlock() is called,
 *       or a race condition is triggered !
 */
void DRD_(mutex_unlock)(const Addr mutex, MutexT mutex_type)
{
  const DrdThreadId drd_tid = DRD_(thread_get_running_tid)();
  const ThreadId vg_tid = VG_(get_running_tid)();
  struct mutex_info* p;

  p = DRD_(mutex_get)(mutex);
  if (mutex_type == mutex_type_unknown)
    mutex_type = p->mutex_type;

  if (DRD_(s_trace_mutex))
  {
    VG_(message)(Vg_UserMsg,
                 "[%d/%d] mutex_unlock    %s 0x%lx rc %d",
                 vg_tid,
                 drd_tid,
                 p ? DRD_(mutex_get_typename)(p) : "(?)",
                 mutex,
                 p ? p->recursion_count : 0);
  }

  if (p == 0 || mutex_type == mutex_type_invalid_mutex)
  {
    DRD_(not_a_mutex)(mutex);
    return;
  }

  if (p->owner == DRD_INVALID_THREADID)
  {
    MutexErrInfo MEI = { p->a1, p->recursion_count, p->owner };
    VG_(maybe_record_error)(vg_tid,
                            MutexErr,
                            VG_(get_IP)(vg_tid),
                            "Mutex not locked",
                            &MEI);
    return;
  }

  tl_assert(p);
  if (p->mutex_type != mutex_type)
  {
    VG_(message)(Vg_UserMsg, "??? mutex 0x%lx: type changed from %d into %d",
                 p->a1, p->mutex_type, mutex_type);
  }
  tl_assert(p->mutex_type == mutex_type);
  tl_assert(p->owner != DRD_INVALID_THREADID);

  if (p->owner != drd_tid || p->recursion_count <= 0)
  {
    MutexErrInfo MEI = { p->a1, p->recursion_count, p->owner };
    VG_(maybe_record_error)(vg_tid,
                            MutexErr,
                            VG_(get_IP)(vg_tid),
                            "Mutex not locked by calling thread",
                            &MEI);
    return;
  }
  tl_assert(p->recursion_count > 0);
  p->recursion_count--;
  tl_assert(p->recursion_count >= 0);

  if (p->recursion_count == 0)
  {
    if (DRD_(s_mutex_lock_threshold_ms) > 0)
    {
      ULong held = VG_(read_millisecond_timer)() - p->acquiry_time_ms;
      if (held > DRD_(s_mutex_lock_threshold_ms))
      {
        HoldtimeErrInfo HEI
          = { mutex, p->acquired_at, held, DRD_(s_mutex_lock_threshold_ms) };
        VG_(maybe_record_error)(vg_tid,
                                HoldtimeErr,
                                VG_(get_IP)(vg_tid),
                                "mutex",
                                &HEI);
      }
    }

    /* This pthread_mutex_unlock() call really unlocks the mutex. Save the */
    /* current vector clock of the thread such that it is available when  */
    /* this mutex is locked again.                                        */

    DRD_(thread_get_latest_segment)(&p->last_locked_segment, drd_tid);
    DRD_(thread_new_segment)(drd_tid);
    p->acquired_at = 0;
    DRD_(s_mutex_segment_creation_count)++;
  }
}

void DRD_(spinlock_init_or_unlock)(const Addr spinlock)
{
  struct mutex_info* mutex_p = DRD_(mutex_get)(spinlock);
  if (mutex_p)
  {
    DRD_(mutex_unlock)(spinlock, mutex_type_spinlock);
  }
  else
  {
    DRD_(mutex_init)(spinlock, mutex_type_spinlock);
  }
}

const char* DRD_(mutex_get_typename)(struct mutex_info* const p)
{
  tl_assert(p);

  return DRD_(mutex_type_name)(p->mutex_type);
}

const char* DRD_(mutex_type_name)(const MutexT mt)
{
  switch (mt)
  {
  case mutex_type_invalid_mutex:
    return "invalid mutex";
  case mutex_type_recursive_mutex:
    return "recursive mutex";
  case mutex_type_errorcheck_mutex:
    return "error checking mutex";
  case mutex_type_default_mutex:
    return "mutex";
  case mutex_type_spinlock:
    return "spinlock";
  default:
    tl_assert(0);
  }
  return "?";
}

/** Return true if the specified mutex is locked by any thread. */
static Bool DRD_(mutex_is_locked)(struct mutex_info* const p)
{
  tl_assert(p);
  return (p->recursion_count > 0);
}

Bool DRD_(mutex_is_locked_by)(const Addr mutex, const DrdThreadId tid)
{
  struct mutex_info* const p = DRD_(mutex_get)(mutex);
  if (p)
  {
    return (p->recursion_count > 0 && p->owner == tid);
  }
  return False;
}

int DRD_(mutex_get_recursion_count)(const Addr mutex)
{
  struct mutex_info* const p = DRD_(mutex_get)(mutex);
  tl_assert(p);
  return p->recursion_count;
}

/**
 * Call this function when thread tid stops to exist, such that the
 * "last owner" field can be cleared if it still refers to that thread.
 */
void DRD_(mutex_thread_delete)(const DrdThreadId tid)
{
  struct mutex_info* p;

  DRD_(clientobj_resetiter)();
  for ( ; (p = &(DRD_(clientobj_next)(ClientMutex)->mutex)) != 0; )
  {
    if (p->owner == tid && p->recursion_count > 0)
    {
      MutexErrInfo MEI
        = { p->a1, p->recursion_count, p->owner };
      VG_(maybe_record_error)(VG_(get_running_tid)(),
                              MutexErr,
                              VG_(get_IP)(VG_(get_running_tid)()),
                              "Mutex still locked at thread exit",
                              &MEI);
      p->owner = VG_INVALID_THREADID;
    }
  }
}

ULong DRD_(get_mutex_lock_count)(void)
{
  return DRD_(s_mutex_lock_count);
}

ULong DRD_(get_mutex_segment_creation_count)(void)
{
  return DRD_(s_mutex_segment_creation_count);
}