From: Frank Mori Hess <fmhess@speakeasy.net>
Date: Sat, 6 Mar 2004 19:08:26 +0000 (+0000)
Subject: added some memory barriers on read/writes to comedi's buffer
X-Git-Tag: r0_7_69~88
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=914b1daabace88feffa2a5d1a1e249eb518de075;p=comedi.git

added some memory barriers on read/writes to comedi's buffer
---

diff --git a/comedi/drivers.c b/comedi/drivers.c
index 1ccf1e25..c41eb2c6 100644
--- a/comedi/drivers.c
+++ b/comedi/drivers.c
@@ -38,6 +38,7 @@
 #include <linux/vmalloc.h>
 
 #include <asm/io.h>
+#include <asm/system.h>
 
 static int postconfig(comedi_device *dev);
 static int insn_rw_emulate_bits(comedi_device *dev,comedi_subdevice *s,
@@ -566,7 +567,7 @@ void comedi_buf_memcpy_to( comedi_async *async, unsigned int offset, const void
 	unsigned int write_ptr = async->buf_write_ptr + offset;
 
 	if( write_ptr >= async->prealloc_bufsz )
-		write_ptr -= async->prealloc_bufsz;
+		write_ptr %= async->prealloc_bufsz;
 
 	while( num_bytes )
 	{
@@ -584,6 +585,7 @@ void comedi_buf_memcpy_to( comedi_async *async, unsigned int offset, const void
 
 		write_ptr = 0;
 	}
+	mb();
 }
 
 void comedi_buf_memcpy_from(comedi_async *async, unsigned int offset,
@@ -593,8 +595,9 @@ void comedi_buf_memcpy_from(comedi_async *async, unsigned int offset,
 	unsigned int read_ptr = async->buf_read_ptr + offset;
 
 	if( read_ptr >= async->prealloc_bufsz )
-		read_ptr -= async->prealloc_bufsz;
+		read_ptr %= async->prealloc_bufsz;
 
+	mb();
 	while( nbytes )
 	{
 		unsigned int block_size;