From 9b5404347869fbee0bc9753a4c14619575704737 Mon Sep 17 00:00:00 2001
From: Arvid Norberg <arvid@libtorrent.org>
Date: Thu, 13 Dec 2007 04:05:25 +0000
Subject: [PATCH] attempt to fix potential deadlock in disk_io_thread

---
 include/libtorrent/disk_io_thread.hpp |  3 ++-
 src/disk_io_thread.cpp                | 34 +++++++++------------------
 2 files changed, 13 insertions(+), 24 deletions(-)

diff --git a/include/libtorrent/disk_io_thread.hpp b/include/libtorrent/disk_io_thread.hpp
index b93ea8b75..a77522356 100644
--- a/include/libtorrent/disk_io_thread.hpp
+++ b/include/libtorrent/disk_io_thread.hpp
@@ -124,7 +124,8 @@ namespace libtorrent
 
 	private:
 
-		mutable boost::mutex m_mutex;
+		typedef boost::recursive_mutex mutex_t;
+		mutable mutex_t m_mutex;
 		boost::condition m_signal;
 		bool m_abort;
 		std::deque<disk_io_job> m_jobs;
diff --git a/src/disk_io_thread.cpp b/src/disk_io_thread.cpp
index a9446f664..e0fa982bc 100644
--- a/src/disk_io_thread.cpp
+++ b/src/disk_io_thread.cpp
@@ -62,7 +62,7 @@ namespace libtorrent
 
 	disk_io_thread::~disk_io_thread()
 	{
-		boost::mutex::scoped_lock l(m_mutex);
+		mutex_t::scoped_lock l(m_mutex);
 		m_abort = true;
 		m_signal.notify_all();
 		l.unlock();
@@ -74,7 +74,7 @@ namespace libtorrent
 	disk_io_job disk_io_thread::find_job(boost::intrusive_ptr<piece_manager> s
 		, int action, int piece) const
 	{
-		boost::mutex::scoped_lock l(m_mutex);
+		mutex_t::scoped_lock l(m_mutex);
 		for (std::deque<disk_io_job>::const_iterator i = m_jobs.begin();
 			i != m_jobs.end(); ++i)
 		{
@@ -98,7 +98,7 @@ namespace libtorrent
 	// aborts read operations
 	void disk_io_thread::stop(boost::intrusive_ptr<piece_manager> s)
 	{
-		boost::mutex::scoped_lock l(m_mutex);
+		mutex_t::scoped_lock l(m_mutex);
 		// read jobs are aborted, write and move jobs are syncronized
 		for (std::deque<disk_io_job>::iterator i = m_jobs.begin();
 			i != m_jobs.end();)
@@ -151,7 +151,7 @@ namespace libtorrent
 	{
 		TORRENT_ASSERT(!j.callback);
 		TORRENT_ASSERT(j.storage);
-		boost::mutex::scoped_lock l(m_mutex);
+		mutex_t::scoped_lock l(m_mutex);
 		
 		std::deque<disk_io_job>::reverse_iterator i = m_jobs.rbegin();
 		if (j.action == disk_io_job::read)
@@ -206,7 +206,7 @@ namespace libtorrent
 
 	char* disk_io_thread::allocate_buffer()
 	{
-		boost::mutex::scoped_lock l(m_mutex);
+		mutex_t::scoped_lock l(m_mutex);
 #ifdef TORRENT_STATS
 		++m_allocations;
 #endif
@@ -215,7 +215,7 @@ namespace libtorrent
 
 	void disk_io_thread::free_buffer(char* buf)
 	{
-		boost::mutex::scoped_lock l(m_mutex);
+		mutex_t::scoped_lock l(m_mutex);
 #ifdef TORRENT_STATS
 		--m_allocations;
 #endif
@@ -229,7 +229,7 @@ namespace libtorrent
 #ifdef TORRENT_DISK_STATS
 			m_log << log_time() << " idle" << std::endl;
 #endif
-			boost::mutex::scoped_lock l(m_mutex);
+			mutex_t::scoped_lock l(m_mutex);
 #ifndef NDEBUG
 			m_current.action = (disk_io_job::action_t)-1;
 			m_current.piece = -1;
@@ -250,7 +250,7 @@ namespace libtorrent
 
 			int ret = 0;
 
-			bool free_buffer = true;
+			bool free_current_buffer = true;
 			try
 			{
 				TORRENT_ASSERT(j.storage);
@@ -264,15 +264,10 @@ namespace libtorrent
 #ifdef TORRENT_DISK_STATS
 						m_log << log_time() << " read " << j.buffer_size << std::endl;
 #endif
-						free_buffer = false;
+						free_current_buffer = false;
 						if (j.buffer == 0)
 						{
-							l.lock();
-							j.buffer = (char*)m_pool.ordered_malloc();
-#ifdef TORRENT_STATS
-							++m_allocations;
-#endif
-							l.unlock();
+							j.buffer = allocate_buffer();
 							TORRENT_ASSERT(j.buffer_size <= m_block_size);
 							if (j.buffer == 0)
 							{
@@ -347,14 +342,7 @@ namespace libtorrent
 			m_current.callback.clear();
 #endif
 			
-			if (j.buffer && free_buffer)
-			{
-				l.lock();
-				m_pool.ordered_free(j.buffer);
-#ifdef TORRENT_STATS
-				--m_allocations;
-#endif
-			}
+			if (j.buffer && free_current_buffer) free_buffer(j.buffer);
 		}
 	}
 }