Both Mutex and CondVar signal PerThreadSem/Waiter after satisfying the wait condition,
as the result the waiting thread may return w/o waiting on the
PerThreadSem/Waiter at all. If the waiting thread then exits, it currently
destroys Waiter object. As the result Waiter::Post can be called on
already destroyed object.
PerThreadSem/Waiter must be type-stable after creation and must not be destroyed.
The futex-based implementation is the only one that is not affected by the bug
since there is effectively nothing to destroy (maybe only UBSan/ASan
could complain about calling methods on a destroyed object).
Here is the problematic sequence of events:
1: void Mutex::Block(PerThreadSynch *s) {
2: while (s->state.load(std::memory_order_acquire) == PerThreadSynch::kQueued) {
3: if (!DecrementSynchSem(this, s, s->waitp->timeout)) {
4: PerThreadSynch *Mutex::Wakeup(PerThreadSynch *w) {
5: ...
6: w->state.store(PerThreadSynch::kAvailable, std::memory_order_release);
7: IncrementSynchSem(this, w);
8: ...
9: }
Consider line 6 is executed, then line 2 observes kAvailable and
line 3 is not called. The thread executing Mutex::Block returns from
the method, acquires the mutex, releases the mutex, exits and destroys
PerThreadSem/Waiter.
Now Mutex::Wakeup resumes and executes line 7 on the destroyed object. Boom!
CondVar uses a similar pattern.
Moreover the semaphore-based Waiter implementation is not even destruction-safe
(the Waiter cannot be used to signal own destruction). So even if Mutex/CondVar
would always pair Waiter::Post with Waiter::Wait before destroying PerThreadSem/Waiter,
it would still be subject to use-after-free bug on the semaphore.
PiperOrigin-RevId: 449159939
Change-Id: I497134fa8b6ce1294a422827c5f0de0e897cea31
--
17141711ee419daa597a9f31e73721f80143e55a by Gennadiy Rozental <rogeeff@google.com>:
Import of CCTZ from GitHub.
PiperOrigin-RevId: 401384949
--
ac48584a7b16e8a12e26d49deb6cddec584a20b5 by Derek Mauro <dmauro@google.com>:
Internal change
PiperOrigin-RevId: 401337785
--
8a51bb7c962845e0707240c5ba12c1b80f6fbbe9 by Derek Mauro <dmauro@google.com>:
Internal change
PiperOrigin-RevId: 401047691
--
8e18024510869247f3c04c7807c93709eca2322a by Chris Kennelly <ckennelly@google.com>:
Note that SpinLock does not guarantee priorities for wakeups.
PiperOrigin-RevId: 400999238
--
75bc09b5f95fbb74b74d14c370bfb80011e8fb7f by Derek Mauro <dmauro@google.com>:
Add visibility restrictions to some internal targets
PiperOrigin-RevId: 400718253
--
1de5061016bc42cd7be009c9725ed2343ce12e3d by Abseil Team <absl-team@google.com>:
Make it clear that operator<< can also be used in place of ToString when logging absl::Status.
PiperOrigin-RevId: 400248269
--
cda15d9dc6e5cd569de7e5e73f409b72a3caed51 by Abseil Team <absl-team@google.com>:
Minor cleanup
PiperOrigin-RevId: 400087535
--
b001375ec47da3a0434be9ca9a45c0df510e7dda by Abseil Team <absl-team@google.com>:
Move periodic_sampler from base/internal to profiling/internal
PiperOrigin-RevId: 400038533
--
e7e02e686abc3900e723080849a3607d190ef57f by Abseil Team <absl-team@google.com>:
Move exponential_biased from base/internal to profiling/internal
PiperOrigin-RevId: 400020329
GitOrigin-RevId: 17141711ee419daa597a9f31e73721f80143e55a
Change-Id: I10924df7e1cc198447813dbe97a374a5cef66b49
--
1e0b6c504e9edc93ac08de320454b0e7f61f2028 by Derek Mauro <dmauro@google.com>:
Use ABSL_NO_THREAD_SAFETY_ANALYSIS instead of the
no-namespace NO_THREAD_SAFETY_ANALYSIS
PiperOrigin-RevId: 363914253
GitOrigin-RevId: 1e0b6c504e9edc93ac08de320454b0e7f61f2028
Change-Id: Iea54f88130d93066e1e4a4747e902f1029500f71
--
0e3e8be75b3ab243991c9b28a27623d86e4511e6 by Abseil Team <absl-team@google.com>:
Add constructor overloads with signature (Mutex*, const Condition&) to MutexLock, ReaderMutexLock, WriterMutexLock, ReleasableMutexLock, MaybeMutexLock.
These overloads call Mutex::LockWhen, Mutex::ReaderLockWhen, Mutex::WriterLockWhen.
Using the guard classes with these new constructors replaces both manual LockWhen/Unlock sequences and the less-efficient, but popular current pattern of "absl::MutexLock lock(&mu); mu.Await(cond);".
PiperOrigin-RevId: 339480213
--
ff999bc08360f5bd95557147c97b0e7b200fe3a8 by Jorg Brown <jorg@google.com>:
ConvertibleToStringView wastes a lot of cycles initializing members just to reset them immediately after. Only initialize the string storage when needed. This makes StrSplit() 0-30% faster depending on the use case.
PiperOrigin-RevId: 339479046
--
0a773bfb8bc141433a41388731357001fdb34881 by Derek Mauro <dmauro@google.com>:
Remove the compiler upgrade fiasco inducing -Weverything -Werror.
Switch to a curated set of warnings that may be expanded in the future.
PiperOrigin-RevId: 339472677
--
eab54e3e11b126283d33f64c914b200038d215a4 by Abseil Team <absl-team@google.com>:
Change execute permission to match presence of the shebang
remove execute permission for cmake_common.sh
add execute permission for conanfile.py
PiperOrigin-RevId: 339453550
--
7f9726fb605ed20f17f3e221dbce0df03d6904c6 by Abseil Team <absl-team@google.com>:
Internal change
PiperOrigin-RevId: 339385761
--
f3210dbee3e8a719cf31706963721722203f90e0 by Derek Mauro <dmauro@google.com>:
Switch clang compiler detection to use to the Bazel supported mechanism
When Abseil launched, we relied on the compiler string "llvm",
which we manually set when we used the automatic crosstool generation
by using the environment variable BAZEL_COMPILER. Today, Bazel detects
clang and automatically sets the compiler string to "clang".
Fixes#732
PiperOrigin-RevId: 339360688
--
413211f59e5e671bf5774efa63ab4df185c74248 by Abseil Team <absl-team@google.com>:
Minor comment clarifications and cosmetic tweaks.
PiperOrigin-RevId: 339344301
GitOrigin-RevId: 0e3e8be75b3ab243991c9b28a27623d86e4511e6
Change-Id: Ia5b7224cd3d274c79ec7f5514fef63014f458f0f
--
f50d25c8f8491ef7031cbbcad78edd15f98c2bd1 by Abseil Team <absl-team@google.com>:
Add myriad2 to HAVE_MMAP
Remove mutex_nonprod and associated defines.
PiperOrigin-RevId: 333759830
--
25ef4c577ea983aa3fcd6cfe2af6cdc62a06f520 by Samuel Benzaquen <sbenza@google.com>:
Internal refactor.
Represent the data with a union to allow for better constexpr support in the future.
PiperOrigin-RevId: 333756733
GitOrigin-RevId: f50d25c8f8491ef7031cbbcad78edd15f98c2bd1
Change-Id: Ieecd2c47cb20de638726eb3f9fc2e5682d05dcca
--
9214ee309fa224a43eb1621bcf826ab9c86a4cd7 by Abseil Team <absl-team@google.com>:
Don't keep constructing/destructing `random_device`.
It causes an open/close pair on /dev/urandom.
This is somewhat expensive on Emscripten, and unnecessary since it is not using
the value anyway.
PiperOrigin-RevId: 332055452
--
4931ab77995b946f3ffba8036e0a00927b0d47e6 by Abseil Team <absl-team@google.com>:
TYPO: Stess->Stress
PiperOrigin-RevId: 332010526
--
95ae1dde505f74dc7fd68447bf27718db223688e by Gennadiy Rozental <rogeeff@google.com>:
Import of CCTZ from GitHub.
PiperOrigin-RevId: 332010411
GitOrigin-RevId: 9214ee309fa224a43eb1621bcf826ab9c86a4cd7
Change-Id: I23c5d6aa5aa488370e1b48f37366d3d99448e7ec
--
587e6db882749fa7faa12815e614afab04d218b9 by Derek Mauro <dmauro@google.com>:
Use attribute detection for other sanitizer related attributes
PiperOrigin-RevId: 324077073
--
3ee55e4935b4235516b1fcac3c55945e510f7afc by Evan Brown <ezb@google.com>:
Simplify CordRepExternal allocation/deallocation.
I think this can save some memory when `Releaser` is empty and when on platforms where alignof(CordRepExternal) < (default `::operator new` alignment).
We no longer need the API requirement that alignof(Releaser) <= (default `::operator new` alignment).
Also remove another static_assert from a TODO in cord_internal.h and fix some warnings about calling std::move on a forwarding reference.
PiperOrigin-RevId: 324053720
--
9fc78436565eb3b204d4aa425ee3773354392f45 by Derek Mauro <dmauro@google.com>:
Use auto-detected sanitizer attributes for ASAN, MSAN, and TSAN builds
PiperOrigin-RevId: 323831461
GitOrigin-RevId: 587e6db882749fa7faa12815e614afab04d218b9
Change-Id: Ie0e4a2846d7f66988a2d81a5e50721b62fdb3d6d
--
f012012ef78234a6a4585321b67d7b7c92ebc266 by Laramie Leavitt <lar@google.com>:
Slight restructuring of absl/random/internal randen implementation.
Convert round-keys.inc into randen_round_keys.cc file.
Consistently use a 128-bit pointer type for internal method parameters. This allows simpler pointer arithmetic in C++ & permits removal of some constants and casts.
Remove some redundancy in comments & constexpr variables. Specifically, all references to Randen algorithm parameters use RandenTraits; duplication in RandenSlow removed.
PiperOrigin-RevId: 312190313
--
dc8b42e054046741e9ed65335bfdface997c6063 by Abseil Team <absl-team@google.com>:
Internal change.
PiperOrigin-RevId: 312167304
--
f13d248fafaf206492c1362c3574031aea3abaf7 by Matthew Brown <matthewbr@google.com>:
Cleanup StrFormat extensions a little.
PiperOrigin-RevId: 312166336
--
9d9117589667afe2332bb7ad42bc967ca7c54502 by Derek Mauro <dmauro@google.com>:
Internal change
PiperOrigin-RevId: 312105213
--
9a12b9b3aa0e59b8ee6cf9408ed0029045543a9b by Abseil Team <absl-team@google.com>:
Complete IGNORE_TYPE macro renaming.
PiperOrigin-RevId: 311999699
--
64756f20d61021d999bd0d4c15e9ad3857382f57 by Gennadiy Rozental <rogeeff@google.com>:
Switch to fixed bytes specific default value.
This fixes the Abseil Flags for big endian platforms.
PiperOrigin-RevId: 311844448
--
bdbe6b5b29791dbc3816ada1828458b3010ff1e9 by Laramie Leavitt <lar@google.com>:
Change many distribution tests to use pcg_engine as a deterministic source of entropy.
It's reasonable to test that the BitGen itself has good entropy, however when testing the cross product of all random distributions x all the architecture variations x all submitted changes results in a large number of tests. In order to account for these failures while still using good entropy requires that our allowed sigma need to account for all of these independent tests.
Our current sigma values are too restrictive, and we see a lot of failures, so we have to either relax the sigma values or convert some of the statistical tests to use deterministic values.
This changelist does the latter.
PiperOrigin-RevId: 311840096
GitOrigin-RevId: f012012ef78234a6a4585321b67d7b7c92ebc266
Change-Id: Ic84886f38ff30d7d72c126e9b63c9a61eb729a1a
Abseil Team