1 files changed, 54 insertions, 0 deletions
diff --git a/source/ap/squashfs-tools/0006-uptream-fix-race.patch b/source/ap/squashfs-tools/0006-uptream-fix-race.patch
new file mode 100644
index 00000000..3cefbe5b
--- /dev/null
+++ b/source/ap/squashfs-tools/0006-uptream-fix-race.patch
@@ -0,0 +1,54 @@
+commit de03266983ceb62e5365aac84fcd3b2fd4d16e6f
+Author: Phillip Lougher <phillip@squashfs.org.uk>
+Date:   Thu Sep 18 01:28:11 2014 +0100
+
+    mksquashfs: fix rare race in fragment waiting in filesystem finalisation
+    
+    Fix a rare race condition in fragment waiting when finalising the
+    filesystem.  This is a race condition that was initially fixed in 2009,
+    but inadvertantly re-introduced in the latest release when the code
+    was rewritten.
+    
+    Background:
+    
+    When finalising the filesystem, the main control thread needs to ensure
+    all the in-flight fragments have been queued to the writer thread before
+    asking the writer thread to finish, and then writing the metadata.
+    
+    It does this by waiting on the fragments_outstanding counter.  Once this
+    counter reaches 0, it synchronises with the writer thread, waiting until
+    the writer thread reports no outstanding data to be written.
+    
+    However, the main thread can race with the fragment deflator thread(s)
+    because the fragment deflator thread(s) decrement the fragments_outstanding
+    counter and release the mutex before queueing the compressed fragment
+    to the writer thread, i.e. the offending code is:
+    
+                            fragments_outstanding --;
+                            pthread_mutex_unlock(&fragment_mutex);
+                            queue_put(to_writer, write_buffer);
+    
+    In extremely rare circumstances, the main thread may see the
+    fragments_outstanding counter is zero before the fragment
+    deflator sends the fragment buffer to the writer thread, and synchronise
+    with the writer thread, and finalise before the fragment has been written.
+    
+    The fix is to ensure the fragment is queued to the writer thread
+    before releasing the mutex.
+    
+    Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
+
+diff --git a/squashfs-tools/mksquashfs.c b/squashfs-tools/mksquashfs.c
+index 87b7d86..f1fcff1 100644
+--- a/squashfs-tools/mksquashfs.c
++++ b/squashfs-tools/mksquashfs.c
+@@ -2445,8 +2445,8 @@ void *frag_deflator(void *arg)
+ 			write_buffer->block = bytes;
+ 			bytes += compressed_size;
+ 			fragments_outstanding --;
+-			pthread_mutex_unlock(&fragment_mutex);
+ 			queue_put(to_writer, write_buffer);
++			pthread_mutex_unlock(&fragment_mutex);
+ 			TRACE("Writing fragment %lld, uncompressed size %d, "
+ 				"compressed size %d\n", file_buffer->block,
+ 				file_buffer->size, compressed_size);