[PATCH 2/4] MN10300: Introduce barriers to replace removed volatilesin gdbstub

[David Howells]

Introduce into the MN10300 gdbstub a couple of barrier() calls to replace the
removed volatility of the input/output index variables for the Rx ring buffer.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

 arch/mn10300/kernel/gdb-io-ttysm.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)


diff --git a/arch/mn10300/kernel/gdb-io-ttysm.c b/arch/mn10300/kernel/gdb-io-ttysm.c
index c545159..e94c25e 100644
--- a/arch/mn10300/kernel/gdb-io-ttysm.c
+++ b/arch/mn10300/kernel/gdb-io-ttysm.c
@@ -196,6 +196,7 @@ int gdbstub_io_rx_char(unsigned char *_ch, int nonblock)
 try_again:
 	/* pull chars out of the buffer */
 	ix = gdbstub_rx_outp;
+	barrier();
 	if (ix == gdbstub_rx_inp) {
 		if (nonblock)
 			return -EAGAIN;
@@ -207,6 +208,7 @@ try_again:
 
 	ch = gdbstub_rx_buffer[ix++];
 	st = gdbstub_rx_buffer[ix++];
+	barrier();
 	gdbstub_rx_outp = ix & (PAGE_SIZE - 1);
 
 	st &= SC01STR_RXF | SC01STR_RBF | SC01STR_FEF | SC01STR_PEF |

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