2006-08-26 02:01:25

by Adrian Bunk

Subject: drivers/char/synclink_gt.c: chars don't have more than 8 bits

The GNU C compiler (SVN version) spotted the following buggy code in
drivers/char/synclink_gt.c:

<-- snip -->

...
static void rx_async(struct slgt_info *info)
{
...
unsigned char *p;
unsigned char status;
...
if ((status = *(p+1) & (BIT9 + BIT8))) {
if (status & BIT9)
icount->parity++;
else if (status & BIT8)
icount->frame++;
/* discard char if tty control flags say so */
if (status & info->ignore_status_mask)
continue;
if (status & BIT9)
stat = TTY_PARITY;
else if (status & BIT8)
stat = TTY_FRAME;
}
...

<-- snip -->

Since there are no bits 8 or 9 in a char this code is currently
dead code.

cu
Adrian

--

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Benjamin Disraeli

2006-08-26 02:51:31

by Paul Fulghum

Subject: Re: drivers/char/synclink_gt.c: chars don't have more than 8 bits

Adrian Bunk wrote:
> The GNU C compiler (SVN version) spotted the following buggy code in
> drivers/char/synclink_gt.c:
> ...
> Since there are no bits 8 or 9 in a char this code is currently
> dead code.

Yes, that is a bug.

Status and data come in byte pairs, bits 9 and 8 are
referenced from the 16 bit combination.

The code is operating on individual bytes in the buffer,
so it should be bits 1 and 0 that are tested.

I will make a patch and post it.

Thanks,
Paul

2006-08-28 19:09:28

by Paul Fulghum

Subject: [PATCH] synclink_gt fix receive tty error handling

Fix receive tty error handling in synclink_gt driver.
Adrian reported compiler warning for incorrect bit test
against char variable. I determined these and other
device specific error bits were incorrectly defined.

Signed-off-by: Paul Fulghum <[email protected]>

--- linux-2.6.18-rc5/drivers/char/synclink_gt.c 2006-08-28 08:39:18.000000000 -0500
+++ b/drivers/char/synclink_gt.c 2006-08-28 10:38:49.000000000 -0500
@@ -391,8 +391,8 @@ static MGSL_PARAMS default_params = {
#define DESC_LIST_SIZE 4096

#define MASK_PARITY BIT1
-#define MASK_FRAMING BIT2
-#define MASK_BREAK BIT3
+#define MASK_FRAMING BIT0
+#define MASK_BREAK BIT14
#define MASK_OVERRUN BIT4

#define GSR 0x00 /* global status */
@@ -1800,17 +1800,17 @@ static void rx_async(struct slgt_info *i

stat = 0;

- if ((status = *(p+1) & (BIT9 + BIT8))) {
- if (status & BIT9)
+ if ((status = *(p+1) & (BIT1 + BIT0))) {
+ if (status & BIT1)
icount->parity++;
- else if (status & BIT8)
+ else if (status & BIT0)
icount->frame++;
/* discard char if tty control flags say so */
if (status & info->ignore_status_mask)
continue;
- if (status & BIT9)
+ if (status & BIT1)
stat = TTY_PARITY;
- else if (status & BIT8)
+ else if (status & BIT0)
stat = TTY_FRAME;
}
if (tty) {