| Issue |
165528
|
| Summary |
False positive on unix.BlockInCriticalSection: not checking destructors
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
halfgaar
|
False positive on `unix.BlockInCriticalSection`; it doesn't see destructors that unlock locks.
Version:
```
$HOME/opt/Qt/Tools/QtCreator/libexec/qtcreator/clang/bin/clang-tidy --version
LLVM (http://llvm.org/):
LLVM version 20.1.3
Optimized build.
```
Repro:
```
#include <unistd.h>
#include <sys/eventfd.h>
#include <mutex>
int main()
{
int fd = eventfd(0, EFD_NONBLOCK);
std::mutex m;
while (true)
{
// This lock gets yielded, but unix.BlockInCriticalSection doesn't see it
std::unique_lock ul(m);
uint64_t eventfd_value = 0;
if (read(fd, &eventfd_value, sizeof(uint64_t)) < 0)
return 1;
}
return 0;
}
```
Error:
```
/home/halfgaar/tmp/block/main.cpp:15:9: warning: Call to blocking function 'read' inside of critical section [clang-analyzer-unix.BlockInCriticalSection]
15 | if (read(fd, &eventfd_value, sizeof(uint64_t)) < 0)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/halfgaar/tmp/block/main.cpp:11:3: note: Loop condition is true. Entering loop body
11 | while (true)
| ^
/home/halfgaar/tmp/block/main.cpp:13:22: note: Calling constructor for 'unique_lock<std::mutex>'
13 | std::unique_lock ul(m);
| ^~~~~
/usr/include/c++/11/bits/unique_lock.h:69:2: note: Calling 'unique_lock::lock'
69 | lock();
| ^~~~~~
/usr/include/c++/11/bits/unique_lock.h:133:7: note: Field '_M_device' is non-null
133 | if (!_M_device)
| ^
/usr/include/c++/11/bits/unique_lock.h:133:2: note: Taking false branch
133 | if (!_M_device)
| ^
/usr/include/c++/11/bits/unique_lock.h:135:11: note: Field '_M_owns' is false
135 | else if (_M_owns)
| ^
/usr/include/c++/11/bits/unique_lock.h:135:7: note: Taking false branch
135 | else if (_M_owns)
| ^
/usr/include/c++/11/bits/unique_lock.h:139:6: note: Calling 'mutex::lock'
139 | _M_device->lock();
| ^~~~~~~~~~~~~~~~~
/usr/include/c++/11/bits/std_mutex.h:100:17: note: Calling '__gthread_mutex_lock'
100 | int __e = __gthread_mutex_lock(&_M_mutex);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/x86_64-linux-gnu/c++/11/bits/gthr-default.h:748:3: note: Taking true branch
748 | if (__gthread_active_p ())
| ^
/usr/include/x86_64-linux-gnu/c++/11/bits/gthr-default.h:749:21: note: Entering critical section here
749 | return __gthrw_(pthread_mutex_lock) (__mutex);
| ^
/usr/include/x86_64-linux-gnu/c++/11/bits/gthr-default.h:96:25: note: expanded from macro '__gthrw_'
96 | # define __gthrw_(name) name
| ^
/usr/include/c++/11/bits/std_mutex.h:100:17: note: Returning from '__gthread_mutex_lock'
100 | int __e = __gthread_mutex_lock(&_M_mutex);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/11/bits/std_mutex.h:103:11: note: Assuming '__e' is 0
103 | if (__e)
| ^~~
/usr/include/c++/11/bits/std_mutex.h:103:7: note: Taking false branch
103 | if (__e)
| ^
/usr/include/c++/11/bits/unique_lock.h:139:6: note: Returning from 'mutex::lock'
139 | _M_device->lock();
| ^~~~~~~~~~~~~~~~~
/usr/include/c++/11/bits/unique_lock.h:139:6: note: Entering critical section here
139 | _M_device->lock();
| ^~~~~~~~~~~~~~~~~
/usr/include/c++/11/bits/unique_lock.h:69:2: note: Returning from 'unique_lock::lock'
69 | lock();
| ^~~~~~
/usr/include/c++/11/bits/unique_lock.h:69:2: note: Entering critical section for the 1st time here
69 | lock();
| ^~~~~~
/home/halfgaar/tmp/block/main.cpp:13:22: note: Returning from constructor for 'unique_lock<std::mutex>'
13 | std::unique_lock ul(m);
| ^~~~~
/home/halfgaar/tmp/block/main.cpp:13:22: note: Entering critical section for the 2nd time here
13 | std::unique_lock ul(m);
| ^~~~~
/home/halfgaar/tmp/block/main.cpp:15:9: note: Call to blocking function 'read' inside of critical section
15 | if (read(fd, &eventfd_value, sizeof(uint64_t)) < 0)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```
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