Summary:
Counters can be flushed in a multi-threaded context for example when the process is forked in different threads (https://github.com/llvm/llvm-project/blob/master/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp#L632-L663).
In order to avoid pretty bad things, a critical section is needed around the flush.
We had a lot of crashes in this code in Firefox CI when we switched to clang for linux ccov builds and those crashes disappeared with this patch.
Reviewers: marco-c, froydnj, dmajor, davidxl
Reviewed By: marco-c, dmajor
Subscribers: froydnj, dmajor, dberris, jfb, #sanitizers, llvm-commits, sylvestre.ledru
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D70910
#include "InstrProfiling.h"
#include "InstrProfilingUtil.h"
-/* #define DEBUG_GCDAPROFILING */
+#ifndef _WIN32
+#include <pthread.h>
+pthread_mutex_t gcov_flush_mutex = PTHREAD_MUTEX_INITIALIZER;
+static __inline void gcov_flush_lock() {
+ pthread_mutex_lock(&gcov_flush_mutex);
+}
+static __inline void gcov_flush_unlock() {
+ pthread_mutex_unlock(&gcov_flush_mutex);
+}
+#else
+#include <windows.h>
+static SRWLOCK gcov_flush_mutex = SRWLOCK_INIT;
+static __inline void gcov_flush_lock() {
+ AcquireSRWLockExclusive(&gcov_flush_mutex);
+}
+static __inline void gcov_flush_unlock() {
+ ReleaseSRWLockExclusive(&gcov_flush_mutex);
+}
+#endif
+/* #define DEBUG_GCDAPROFILING */
/*
* --- GCOV file format I/O primitives ---
*/
}
void __gcov_flush() {
+ gcov_flush_lock();
+
struct fn_node* curr = flush_fn_list.head;
while (curr) {
curr->fn();
curr = curr->next;
}
+
+ gcov_flush_unlock();
}
COMPILER_RT_VISIBILITY