[llvm] r202570 - Fix RWMutex to be thread-safe when pthread_rwlock is not available
Mark Seaborn
mseaborn at chromium.org
Fri Feb 28 20:30:32 PST 2014
Author: mseaborn
Date: Fri Feb 28 22:30:32 2014
New Revision: 202570
URL: http://llvm.org/viewvc/llvm-project?rev=202570&view=rev
Log:
Fix RWMutex to be thread-safe when pthread_rwlock is not available
lib/Support/RWMutex.cpp contains an implementation of RWMutex that
uses pthread_rwlock, but when pthread_rwlock is not available (such as
under NaCl, when using newlib), it silently falls back to using the
no-op definition in lib/Support/Unix/RWMutex.inc, which is not
thread-safe.
Fix this case to be thread-safe by using a normal mutex.
Differential Revision: http://llvm-reviews.chandlerc.com/D2892
Modified:
llvm/trunk/lib/Support/Unix/RWMutex.inc
Modified: llvm/trunk/lib/Support/Unix/RWMutex.inc
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Unix/RWMutex.inc?rev=202570&r1=202569&r2=202570&view=diff
==============================================================================
--- llvm/trunk/lib/Support/Unix/RWMutex.inc (original)
+++ llvm/trunk/lib/Support/Unix/RWMutex.inc Fri Feb 28 22:30:32 2014
@@ -16,28 +16,36 @@
//=== is guaranteed to work on *all* UNIX variants.
//===----------------------------------------------------------------------===//
+#include "llvm/Support/Mutex.h"
+
namespace llvm {
using namespace sys;
-RWMutexImpl::RWMutexImpl() { }
+// This naive implementation treats readers the same as writers. This
+// will therefore deadlock if a thread tries to acquire a read lock
+// multiple times.
+
+RWMutexImpl::RWMutexImpl() : data_(new Mutex(false)) { }
-RWMutexImpl::~RWMutexImpl() { }
+RWMutexImpl::~RWMutexImpl() {
+ delete static_cast<Mutex *>(data_);
+}
bool RWMutexImpl::reader_acquire() {
- return true;
+ return static_cast<Mutex *>(data_)->acquire();
}
bool RWMutexImpl::reader_release() {
- return true;
+ return static_cast<Mutex *>(data_)->release();
}
bool RWMutexImpl::writer_acquire() {
- return true;
+ return static_cast<Mutex *>(data_)->acquire();
}
bool RWMutexImpl::writer_release() {
- return true;
+ return static_cast<Mutex *>(data_)->release();
}
}
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