[PATCH 2.6.13-rc3] fix unaligned memory access in snsc_event.c

From: Greg Howard <ghoward_at_sgi.com>
Date: 2005-07-27 03:03:46
Hi Tony,

It's been pointed out that environmental events from the system
controllers on Altix machines cause the kernel to complain about
unaligned memory accesses.  This turns out to be because
"be32_to_cpup()" didn't do everything I thought/hoped it did.
I've added a new function to the file that copies a (big-endian)
integer out of a byte buffer and into a little-endian integer
variable.  Please apply the following patch if it looks right to
you.

Thanks!
- Greg Howard, SGI

Signed-off-by: Greg Howard <ghoward@sgi.com>

diff -uprN -X 0/Documentation/dontdiff 0/drivers/char/snsc_event.c 1/drivers/char/snsc_event.c
--- 0/drivers/char/snsc_event.c	2005-07-12 23:46:46 -05:00
+++ 1/drivers/char/snsc_event.c	2005-07-26 11:34:06 -05:00
@@ -26,6 +26,18 @@ static struct subch_data_s *event_sd;
 void scdrv_event(unsigned long);
 DECLARE_TASKLET(sn_sysctl_event, scdrv_event, 0);

+static int
+copy_buffer_to_int(char *buffer)
+{
+	int i, result = 0;
+	for(i = 0; i < sizeof(result); i++ ) {
+		result |= ((unsigned)(*(unsigned char *)buffer++)
+				<< (8 * ((sizeof(result) - i) - 1)));
+	}
+	return result;
+}
+
+
 /*
  * scdrv_event_interrupt
  *
@@ -64,11 +76,11 @@ scdrv_parse_event(char *event, int *src,
 	char *desc_end;

 	/* record event source address */
-	*src = be32_to_cpup((__be32 *)event);
+	*src = copy_buffer_to_int(event);
 	event += 4; 			/* move on to event code */

 	/* record the system controller's event code */
-	*code = be32_to_cpup((__be32 *)event);
+	*code = copy_buffer_to_int(event);
 	event += 4;			/* move on to event arguments */

 	/* how many arguments are in the packet? */
@@ -82,7 +94,7 @@ scdrv_parse_event(char *event, int *src,
 		/* not an integer argument, so give up */
 		return -1;
 	}
-	*esp_code = be32_to_cpup((__be32 *)event);
+	*esp_code = copy_buffer_to_int(event);
 	event += 4;

 	/* parse out the event description */
-
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Received on Tue Jul 26 13:09:33 2005

This archive was generated by hypermail 2.1.8 : 2005-08-02 09:20:40 EST