scripts: coccinelle: kfree with TRACE_RET before ref is ok (resent)

kfree.cocci currently triggers on constructs like
(resending with proper CC list and subject line)

drivers/staging/rts5208/spi.c
596 if (retval < 0) {

597            kfree(buf);
598            rtsx_clear_spi_error(chip);
599            spi_set_err_code(chip, SPI_HW_ERR);
600            TRACE_RET(chip, STATUS_FAIL);
601    }
602
603    rtsx_stor_access_xfer_buf(buf, pagelen, srb, &index, &offset,
                            TO_XFER_BUF);

with:

./drivers/staging/rts5208/spi.c:603:28-31: ERROR: reference preceded by free on line 597

but this should be fine - so TRACE_RET is added to the list of calls "protecting" access to freed objects see drivers/staging/rts5208/trace.h

---
 scripts/coccinelle/free/kfree.cocci |    2 ++
 1 file changed, 2 insertions(+)

index 577b780..04d3f4f 100644
@@ -101,6 +101,8 @@ kfree at p1(E,...)
 |
  return_ACPI_STATUS(...)
 |
+ TRACE_RET(...)
+|
  E at p2 // bad use
 )
 

1.7.10.4

The TRACE_RET macro is a serious coding style violation. Fix that and the error will go away. Don't change scripts to hide issues with the code. The code above won't just trigger an error in kfree.cocci but also in the head of any sane person.

<quote>
Things to avoid when using macros:

1) macros that affect control flow:

#define FOO(x)                                  \
        do {                                    \
                if (blah(x) < 0)                \
                        return -EBUGGERED;      \
        } while(0)

is a _very_ bad idea. It looks like a function call but exits the "calling" function; don't break the internal parsers of those who will read the code. </quote>

Bj?rn