[dm-devel] Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Andrew Morton]

On Sun, 24 Feb 2008 17:56:09 +0100 Peter Osterlund <petero2 at telia.com> wrote:

> 
>  drivers/block/pktcdvd.c |   16 ++++++++--------
>  1 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
> index 674cd66..f2510e7 100644
> --- a/drivers/block/pktcdvd.c
> +++ b/drivers/block/pktcdvd.c
> @@ -849,7 +849,7 @@ static int pkt_flush_cache(struct pktcdvd_device *pd)
>  /*
>   * speed is given as the normal factor, e.g. 4 for 4x
>   */
> -static int pkt_set_speed(struct pktcdvd_device *pd, unsigned write_speed, unsigned read_speed)
> +static noinline int pkt_set_speed(struct pktcdvd_device *pd, unsigned write_speed, unsigned read_speed)
>
> ...

yup, I'll grab that.  I'll even write your changelog for you (grr).

But first, let's do this:


From: Andrew Morton <akpm at linux-foundation.org>

People are adding `noinline' in various places to prevent excess stack
consumption due to gcc inlining.  But once this is done, it is quite unobvious
why the `noinline' is present in the code.  We can comment each and every
site, or we can use noinline_for_stack.


Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
---

 include/linux/compiler.h |    6 ++++++
 1 file changed, 6 insertions(+)

diff -puN include/linux/compiler.h~add-noinline_for_stack include/linux/compiler.h
--- a/include/linux/compiler.h~add-noinline_for_stack
+++ a/include/linux/compiler.h
@@ -138,6 +138,12 @@ extern void __chk_io_ptr(const volatile 
 #define noinline
 #endif
 
+/*
+ * Rather then using noinline to prevent stack consumption, use
+ * noinline_for_stack instead.  For documentaiton reasons.
+ */
+#define noinline_for_stack noinline
+
 #ifndef __always_inline
 #define __always_inline inline
 #endif
_

(Note that these changes don't let DM off the hook!)