1
2/*--------------------------------------------------------------------*/
3/*--- Definitions for Locks and Threads.                           ---*/
4/*---                                           hg_lock_n_thread.h ---*/
5/*--------------------------------------------------------------------*/
6
7/*
8   This file is part of Helgrind, a Valgrind tool for detecting errors
9   in threaded programs.
10
11   Copyright (C) 2007-2011 OpenWorks Ltd
12      info@open-works.co.uk
13
14   This program is free software; you can redistribute it and/or
15   modify it under the terms of the GNU General Public License as
16   published by the Free Software Foundation; either version 2 of the
17   License, or (at your option) any later version.
18
19   This program is distributed in the hope that it will be useful, but
20   WITHOUT ANY WARRANTY; without even the implied warranty of
21   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
22   General Public License for more details.
23
24   You should have received a copy of the GNU General Public License
25   along with this program; if not, write to the Free Software
26   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
27   02111-1307, USA.
28
29   The GNU General Public License is contained in the file COPYING.
30*/
31
32#ifndef __HG_LOCK_N_THREAD_H
33#define __HG_LOCK_N_THREAD_H
34
35
36/*----------------------------------------------------------------*/
37/*--- Primary data definitions                                 ---*/
38/*----------------------------------------------------------------*/
39
40/* Magic numbers, for doing assertions that structures really are of
41   the right type.  Useful as some of the code can get a bit
42   complex. */
43#define Thread_MAGIC   0x504fc5e5
44#define LockN_MAGIC    0x6545b557 /* normal nonpersistent locks */
45#define LockP_MAGIC    0x755b5456 /* persistent (copied) locks */
46
47
48/* These are handles for Word sets.  CONSTRAINTS: must be small ints
49   numbered from zero, since 32-bit versions of them are used to
50   encode lock-sets in libhb's history records (Thr_n_RCEC). */
51typedef  WordSet  WordSetID;
52
53
54/* Synchronisation Objects, exported abstractly by libhb. */
55typedef  struct _SO  SO;
56
57/* Thr, libhb's private thread record, exported abstractly.  Thr's are
58   allocated and never deallocated (simply leaked).  Also ThrID, which
59   is a small integer which uniquely identifies a Thr and which is
60   used in ScalarTS because it is smaller than a Thr*.  There is a 1-1
61   mapping between Thr's and ThrIDs. */
62typedef  struct _Thr  Thr;
63typedef  UInt         ThrID;
64
65
66/* Stores information about a thread.  Addresses of these also serve
67   as unique thread identifiers and so are never freed, so they should
68   be as small as possible.  Freeing Thread structures makes the
69   storage management just too complex, and most programs don't create
70   many threads, so tolerating this leak seems like a not-bad
71   tradeoff.
72
73   Since these are never freed, the .coretid field only indicates the
74   core's ThreadId associated with this Thread whilst it is alive.
75   Once the thread finishes, the ThreadId is set to
76   VG_INVALID_THREADID.
77
78   The core may later re-use the same ThreadId for what is a logically
79   completely different thread, which of course must have a different
80   Thread structure. */
81typedef
82   struct _Thread {
83      /* ADMIN */
84      struct _Thread* admin;
85      UInt            magic;
86      Thr*            hbthr; /* which in turn points back here .. */
87      ThreadId        coretid;  /* .. via its hgthread field */
88      /* USEFUL */
89      WordSetID locksetA; /* WordSet of Lock* currently held by thread */
90      WordSetID locksetW; /* subset of locksetA held in w-mode */
91      /* EXPOSITION */
92      /* Place where parent was when this thread was created. */
93      ExeContext* created_at;
94      Bool        announced;
95      /* Index for generating references in error messages. */
96      Int         errmsg_index;
97   }
98   Thread;
99
100/* Get hg's admin_threads value, so libhb can visit all of them. */
101Thread* get_admin_threads ( void );
102
103/* Stores information about a lock's current state.  These are
104   allocated and later freed (when the containing memory becomes
105   NoAccess).  This gives a problem for the XError type, which
106   contains Lock*s.  Solution is to copy any Lock which is to be
107   incorporated into an XErrors, so as to make it independent from the
108   'normal' collection of Locks, which can come and go.  When the lock
109   is copied, its .magic is changed from LockN_Magic to
110   LockP_Magic. */
111
112/* Lock kinds. */
113typedef
114   enum {
115      LK_mbRec=1001, /* normal mutex, possibly recursive */
116      LK_nonRec,     /* normal mutex, definitely non recursive */
117      LK_rdwr        /* reader-writer lock */
118   }
119   LockKind;
120
121typedef
122   struct _Lock {
123      /* ADMIN */
124      struct _Lock* admin_next; /* fields for a double linked */
125      struct _Lock* admin_prev; /* list of these locks */
126      ULong         unique; /* used for persistence-hashing */
127      UInt          magic;  /* LockN_MAGIC or LockP_MAGIC */
128      /* EXPOSITION */
129      /* Place where lock first came to the attention of Helgrind. */
130      ExeContext*   appeared_at;
131      /* If the lock is held, place where the lock most recently made
132         an unlocked->locked transition.  Must be sync'd with .heldBy:
133         either both NULL or both non-NULL. */
134      ExeContext*   acquired_at;
135      /* USEFUL-STATIC */
136      SO*           hbso;      /* associated SO */
137      Addr          guestaddr; /* Guest address of lock */
138      LockKind      kind;      /* what kind of lock this is */
139      /* USEFUL-DYNAMIC */
140      Bool          heldW;
141      WordBag*      heldBy; /* bag of threads that hold this lock */
142      /* .heldBy is NULL: lock is unheld, and .heldW is meaningless
143                          but arbitrarily set to False
144         .heldBy is non-NULL:
145            .heldW is True:  lock is w-held by threads in heldBy
146            .heldW is False: lock is r-held by threads in heldBy
147            Either way, heldBy may not validly be an empty Bag.
148
149         for LK_nonRec, r-holdings are not allowed, and w-holdings may
150         only have sizeTotal(heldBy) == 1
151
152         for LK_mbRec, r-holdings are not allowed, and w-holdings may
153         only have sizeUnique(heldBy) == 1
154
155         for LK_rdwr, w-holdings may only have sizeTotal(heldBy) == 1 */
156   }
157   Lock;
158
159#define Lock_INVALID  ((Lock*)1UL)
160
161/*----------------------------------------------------------------*/
162/*--- Sanity checking                                          ---*/
163/*----------------------------------------------------------------*/
164
165Bool HG_(is_sane_Thread)   ( Thread* thr );
166Bool HG_(is_sane_LockP)    ( Lock* lock );
167Bool HG_(is_sane_LockN)    ( Lock* lock );
168Bool HG_(is_sane_LockNorP) ( Lock* lock );
169
170
171#endif /* ! __HG_LOCK_N_THREAD_H */
172
173/*--------------------------------------------------------------------*/
174/*--- end                                       hg_lock_n_thread.h ---*/
175/*--------------------------------------------------------------------*/
176