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Fix RWMutex to be thread-safe when pthread_rwlock is not available

Browse Source 
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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202570 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Mark Seaborn 2014-03-01 04:30:32 +00:00
parent f38b536b3d
commit 79ac85be0b
1 changed files with 14 additions and 6 deletions
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20
lib/Support/Unix/RWMutex.inc
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@ -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() { }
RWMutexImpl::RWMutexImpl() : data_(new Mutex(false)) { }
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();
}
}