VirtualBox

source: vbox/trunk/src/VBox/Runtime/r3/linux/semevent-linux.cpp@ 81137

Last change on this file since 81137 was 76823, checked in by vboxsync, 6 years ago

Runtime/Linux: remove volatile qualifier from freestanding asm blocks.
bugref:9358: Runtime: asm volatile causing problem on Debian Sid.
gcc 8.2 in Debian Sid no longer accepts this construction, and the qualifier
does not make sense for a single freestanding assembly statement.
  • Property svn:eol-style set to native
  • Property svn:keywords set to Id Revision
File size: 12.6 KB
Line 
1/* $Id: semevent-linux.cpp 76823 2019-01-15 12:29:48Z vboxsync $ */
2/** @file
3 * IPRT - Event Semaphore, Linux (2.6.x+).
4 */
5
6/*
7 * Copyright (C) 2006-2019 Oracle Corporation
8 *
9 * This file is part of VirtualBox Open Source Edition (OSE), as
10 * available from http://www.virtualbox.org. This file is free software;
11 * you can redistribute it and/or modify it under the terms of the GNU
12 * General Public License (GPL) as published by the Free Software
13 * Foundation, in version 2 as it comes in the "COPYING" file of the
14 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16 *
17 * The contents of this file may alternatively be used under the terms
18 * of the Common Development and Distribution License Version 1.0
19 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20 * VirtualBox OSE distribution, in which case the provisions of the
21 * CDDL are applicable instead of those of the GPL.
22 *
23 * You may elect to license modified versions of this file under the
24 * terms and conditions of either the GPL or the CDDL or both.
25 */
26
27#include <features.h>
28#if __GLIBC_PREREQ(2,6) && !defined(IPRT_WITH_FUTEX_BASED_SEMS)
29
30/*
31 * glibc 2.6 fixed a serious bug in the mutex implementation. We wrote this
32 * linux specific event semaphores code in order to work around the bug. We
33 * will fall back on the pthread-based implementation if glibc is known to
34 * contain the bug fix.
35 *
36 * The external reference to epoll_pwait is a hack which prevents that we link
37 * against glibc < 2.6.
38 */
39#include "../posix/semevent-posix.cpp"
40__asm__ (".global epoll_pwait");
41
42#else /* glibc < 2.6 */
43
44
45/*********************************************************************************************************************************
46* Header Files *
47*********************************************************************************************************************************/
48#include <iprt/semaphore.h>
49#include "internal/iprt.h"
50
51#include <iprt/asm.h>
52#include <iprt/assert.h>
53#include <iprt/err.h>
54#include <iprt/lockvalidator.h>
55#include <iprt/mem.h>
56#include <iprt/time.h>
57#include "internal/magics.h"
58#include "internal/mem.h"
59#include "internal/strict.h"
60
61#include <errno.h>
62#include <limits.h>
63#include <pthread.h>
64#include <unistd.h>
65#include <sys/time.h>
66#include <sys/syscall.h>
67#if 0 /* With 2.6.17 futex.h has become C++ unfriendly. */
68# include <linux/futex.h>
69#else
70# define FUTEX_WAIT 0
71# define FUTEX_WAKE 1
72#endif
73
74
75/*********************************************************************************************************************************
76* Structures and Typedefs *
77*********************************************************************************************************************************/
78/**
79 * Linux (single wakup) event semaphore.
80 */
81struct RTSEMEVENTINTERNAL
82{
83 /** Magic value. */
84 intptr_t volatile iMagic;
85 /** The futex state variable.
86 * 0 means not signalled.
87 1 means signalled. */
88 uint32_t volatile fSignalled;
89 /** The number of waiting threads */
90 int32_t volatile cWaiters;
91#ifdef RTSEMEVENT_STRICT
92 /** Signallers. */
93 RTLOCKVALRECSHRD Signallers;
94 /** Indicates that lock validation should be performed. */
95 bool volatile fEverHadSignallers;
96#endif
97 /** The creation flags. */
98 uint32_t fFlags;
99};
100
101
102/**
103 * Wrapper for the futex syscall.
104 */
105static long sys_futex(uint32_t volatile *uaddr, int op, int val, struct timespec *utime, int32_t *uaddr2, int val3)
106{
107 errno = 0;
108 long rc = syscall(__NR_futex, uaddr, op, val, utime, uaddr2, val3);
109 if (rc < 0)
110 {
111 Assert(rc == -1);
112 rc = -errno;
113 }
114 return rc;
115}
116
117
118
119RTDECL(int) RTSemEventCreate(PRTSEMEVENT phEventSem)
120{
121 return RTSemEventCreateEx(phEventSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, NULL);
122}
123
124
125RTDECL(int) RTSemEventCreateEx(PRTSEMEVENT phEventSem, uint32_t fFlags, RTLOCKVALCLASS hClass, const char *pszNameFmt, ...)
126{
127 AssertReturn(!(fFlags & ~(RTSEMEVENT_FLAGS_NO_LOCK_VAL | RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)), VERR_INVALID_PARAMETER);
128 Assert(!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK) || (fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL));
129
130 /*
131 * Allocate semaphore handle.
132 */
133 struct RTSEMEVENTINTERNAL *pThis;
134 if (!(fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK))
135 pThis = (struct RTSEMEVENTINTERNAL *)RTMemAlloc(sizeof(struct RTSEMEVENTINTERNAL));
136 else
137 pThis = (struct RTSEMEVENTINTERNAL *)rtMemBaseAlloc(sizeof(struct RTSEMEVENTINTERNAL));
138 if (pThis)
139 {
140 pThis->iMagic = RTSEMEVENT_MAGIC;
141 pThis->cWaiters = 0;
142 pThis->fSignalled = 0;
143 pThis->fFlags = fFlags;
144#ifdef RTSEMEVENT_STRICT
145 if (!pszNameFmt)
146 {
147 static uint32_t volatile s_iSemEventAnon = 0;
148 RTLockValidatorRecSharedInit(&pThis->Signallers, hClass, RTLOCKVAL_SUB_CLASS_ANY, pThis,
149 true /*fSignaller*/, !(fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL),
150 "RTSemEvent-%u", ASMAtomicIncU32(&s_iSemEventAnon) - 1);
151 }
152 else
153 {
154 va_list va;
155 va_start(va, pszNameFmt);
156 RTLockValidatorRecSharedInitV(&pThis->Signallers, hClass, RTLOCKVAL_SUB_CLASS_ANY, pThis,
157 true /*fSignaller*/, !(fFlags & RTSEMEVENT_FLAGS_NO_LOCK_VAL),
158 pszNameFmt, va);
159 va_end(va);
160 }
161 pThis->fEverHadSignallers = false;
162#else
163 RT_NOREF(hClass, pszNameFmt);
164#endif
165
166 *phEventSem = pThis;
167 return VINF_SUCCESS;
168 }
169 return VERR_NO_MEMORY;
170}
171
172
173RTDECL(int) RTSemEventDestroy(RTSEMEVENT hEventSem)
174{
175 /*
176 * Validate input.
177 */
178 struct RTSEMEVENTINTERNAL *pThis = hEventSem;
179 if (pThis == NIL_RTSEMEVENT)
180 return VINF_SUCCESS;
181 AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
182 AssertReturn(pThis->iMagic == RTSEMEVENT_MAGIC, VERR_INVALID_HANDLE);
183
184 /*
185 * Invalidate the semaphore and wake up anyone waiting on it.
186 */
187 ASMAtomicXchgSize(&pThis->iMagic, RTSEMEVENT_MAGIC | UINT32_C(0x80000000));
188 if (ASMAtomicXchgS32(&pThis->cWaiters, INT32_MIN / 2) > 0)
189 {
190 sys_futex(&pThis->fSignalled, FUTEX_WAKE, INT_MAX, NULL, NULL, 0);
191 usleep(1000);
192 }
193
194 /*
195 * Free the semaphore memory and be gone.
196 */
197#ifdef RTSEMEVENT_STRICT
198 RTLockValidatorRecSharedDelete(&pThis->Signallers);
199#endif
200 if (!(pThis->fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK))
201 RTMemFree(pThis);
202 else
203 rtMemBaseFree(pThis);
204 return VINF_SUCCESS;
205}
206
207
208RTDECL(int) RTSemEventSignal(RTSEMEVENT hEventSem)
209{
210 /*
211 * Validate input.
212 */
213 struct RTSEMEVENTINTERNAL *pThis = hEventSem;
214 AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
215 AssertReturn(pThis->iMagic == RTSEMEVENT_MAGIC, VERR_INVALID_HANDLE);
216
217#ifdef RTSEMEVENT_STRICT
218 if (pThis->fEverHadSignallers)
219 {
220 int rc9 = RTLockValidatorRecSharedCheckSignaller(&pThis->Signallers, NIL_RTTHREAD);
221 if (RT_FAILURE(rc9))
222 return rc9;
223 }
224#endif
225
226 ASMAtomicWriteU32(&pThis->fSignalled, 1);
227 if (ASMAtomicReadS32(&pThis->cWaiters) < 1)
228 return VINF_SUCCESS;
229
230 /* somebody is waiting, try wake up one of them. */
231 long cWoken = sys_futex(&pThis->fSignalled, FUTEX_WAKE, 1, NULL, NULL, 0);
232 if (RT_LIKELY(cWoken >= 0))
233 return VINF_SUCCESS;
234
235 if (RT_UNLIKELY(pThis->iMagic != RTSEMEVENT_MAGIC))
236 return VERR_SEM_DESTROYED;
237
238 return VERR_INVALID_PARAMETER;
239}
240
241
242static int rtSemEventWait(RTSEMEVENT hEventSem, RTMSINTERVAL cMillies, bool fAutoResume)
243{
244#ifdef RTSEMEVENT_STRICT
245 PCRTLOCKVALSRCPOS pSrcPos = NULL;
246#endif
247
248 /*
249 * Validate input.
250 */
251 struct RTSEMEVENTINTERNAL *pThis = hEventSem;
252 AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
253 AssertReturn(pThis->iMagic == RTSEMEVENT_MAGIC, VERR_INVALID_HANDLE);
254
255 /*
256 * Quickly check whether it's signaled.
257 */
258 /** @todo this isn't fair if someone is already waiting on it. They should
259 * have the first go at it!
260 * (ASMAtomicReadS32(&pThis->cWaiters) == 0 || !cMillies) && ... */
261 if (ASMAtomicCmpXchgU32(&pThis->fSignalled, 0, 1))
262 return VINF_SUCCESS;
263
264 /*
265 * Convert the timeout value.
266 */
267 struct timespec ts;
268 struct timespec *pTimeout = NULL;
269 uint64_t u64End = 0; /* shut up gcc */
270 if (cMillies != RT_INDEFINITE_WAIT)
271 {
272 if (!cMillies)
273 return VERR_TIMEOUT;
274 ts.tv_sec = cMillies / 1000;
275 ts.tv_nsec = (cMillies % 1000) * UINT32_C(1000000);
276 u64End = RTTimeSystemNanoTS() + cMillies * UINT64_C(1000000);
277 pTimeout = &ts;
278 }
279
280 ASMAtomicIncS32(&pThis->cWaiters);
281
282 /*
283 * The wait loop.
284 */
285#ifdef RTSEMEVENT_STRICT
286 RTTHREAD hThreadSelf = !(pThis->fFlags & RTSEMEVENT_FLAGS_BOOTSTRAP_HACK)
287 ? RTThreadSelfAutoAdopt()
288 : RTThreadSelf();
289#else
290 RTTHREAD hThreadSelf = RTThreadSelf();
291#endif
292 int rc = VINF_SUCCESS;
293 for (;;)
294 {
295#ifdef RTSEMEVENT_STRICT
296 if (pThis->fEverHadSignallers)
297 {
298 rc = RTLockValidatorRecSharedCheckBlocking(&pThis->Signallers, hThreadSelf, pSrcPos, false,
299 cMillies, RTTHREADSTATE_EVENT, true);
300 if (RT_FAILURE(rc))
301 break;
302 }
303#endif
304 RTThreadBlocking(hThreadSelf, RTTHREADSTATE_EVENT, true);
305 long lrc = sys_futex(&pThis->fSignalled, FUTEX_WAIT, 0, pTimeout, NULL, 0);
306 RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_EVENT);
307 if (RT_UNLIKELY(pThis->iMagic != RTSEMEVENT_MAGIC))
308 {
309 rc = VERR_SEM_DESTROYED;
310 break;
311 }
312
313 if (RT_LIKELY(lrc == 0 || lrc == -EWOULDBLOCK))
314 {
315 /* successful wakeup or fSignalled > 0 in the meantime */
316 if (ASMAtomicCmpXchgU32(&pThis->fSignalled, 0, 1))
317 break;
318 }
319 else if (lrc == -ETIMEDOUT)
320 {
321 rc = VERR_TIMEOUT;
322 break;
323 }
324 else if (lrc == -EINTR)
325 {
326 if (!fAutoResume)
327 {
328 rc = VERR_INTERRUPTED;
329 break;
330 }
331 }
332 else
333 {
334 /* this shouldn't happen! */
335 AssertMsgFailed(("rc=%ld errno=%d\n", lrc, errno));
336 rc = RTErrConvertFromErrno(lrc);
337 break;
338 }
339 /* adjust the relative timeout */
340 if (pTimeout)
341 {
342 int64_t i64Diff = u64End - RTTimeSystemNanoTS();
343 if (i64Diff < 1000)
344 {
345 rc = VERR_TIMEOUT;
346 break;
347 }
348 ts.tv_sec = (uint64_t)i64Diff / UINT32_C(1000000000);
349 ts.tv_nsec = (uint64_t)i64Diff % UINT32_C(1000000000);
350 }
351 }
352
353 ASMAtomicDecS32(&pThis->cWaiters);
354 return rc;
355}
356
357
358RTDECL(int) RTSemEventWait(RTSEMEVENT hEventSem, RTMSINTERVAL cMillies)
359{
360 int rc = rtSemEventWait(hEventSem, cMillies, true);
361 Assert(rc != VERR_INTERRUPTED);
362 Assert(rc != VERR_TIMEOUT || cMillies != RT_INDEFINITE_WAIT);
363 return rc;
364}
365
366
367RTDECL(int) RTSemEventWaitNoResume(RTSEMEVENT hEventSem, RTMSINTERVAL cMillies)
368{
369 return rtSemEventWait(hEventSem, cMillies, false);
370}
371
372
373RTDECL(void) RTSemEventSetSignaller(RTSEMEVENT hEventSem, RTTHREAD hThread)
374{
375#ifdef RTSEMEVENT_STRICT
376 struct RTSEMEVENTINTERNAL *pThis = hEventSem;
377 AssertPtrReturnVoid(pThis);
378 AssertReturnVoid(pThis->iMagic == RTSEMEVENT_MAGIC);
379
380 ASMAtomicWriteBool(&pThis->fEverHadSignallers, true);
381 RTLockValidatorRecSharedResetOwner(&pThis->Signallers, hThread, NULL);
382#else
383 RT_NOREF(hEventSem, hThread);
384#endif
385}
386
387
388RTDECL(void) RTSemEventAddSignaller(RTSEMEVENT hEventSem, RTTHREAD hThread)
389{
390#ifdef RTSEMEVENT_STRICT
391 struct RTSEMEVENTINTERNAL *pThis = hEventSem;
392 AssertPtrReturnVoid(pThis);
393 AssertReturnVoid(pThis->iMagic == RTSEMEVENT_MAGIC);
394
395 ASMAtomicWriteBool(&pThis->fEverHadSignallers, true);
396 RTLockValidatorRecSharedAddOwner(&pThis->Signallers, hThread, NULL);
397#else
398 RT_NOREF(hEventSem, hThread);
399#endif
400}
401
402
403RTDECL(void) RTSemEventRemoveSignaller(RTSEMEVENT hEventSem, RTTHREAD hThread)
404{
405#ifdef RTSEMEVENT_STRICT
406 struct RTSEMEVENTINTERNAL *pThis = hEventSem;
407 AssertPtrReturnVoid(pThis);
408 AssertReturnVoid(pThis->iMagic == RTSEMEVENT_MAGIC);
409
410 RTLockValidatorRecSharedRemoveOwner(&pThis->Signallers, hThread);
411#else
412 RT_NOREF(hEventSem, hThread);
413#endif
414}
415
416#endif /* glibc < 2.6 || IPRT_WITH_FUTEX_BASED_SEMS */
417
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