diff mbox series

[hotfix,6.11,v2,3/3] minmax: reduce min/max macro expansion in atomisp driver

Message ID b38d8936eaddd524d19823f7429138e2ef24e0d1.1726074904.git.lorenzo.stoakes@oracle.com (mailing list archive)
State New
Headers show
Series minmax: reduce egregious min/max macro expansion | expand

Commit Message

Lorenzo Stoakes Sept. 11, 2024, 5:51 p.m. UTC 
Avoid unnecessary nested min()/max() which results in egregious macro
expansion. Use clamp_t() as this introduces the least possible expansion.

Not doing so results in an impact on build times.

This resolves an issue with slackware 15.0 32-bit compilation as reported
by Richard Narron.

Presumably the min/max fixups would be difficult to backport, this patch
should be easier and fix's Richard's problem in 5.15.

Reported-by: Richard Narron <richard@aaazen.com>
Closes: https://lore.kernel.org/all/4a5321bd-b1f-1832-f0c-cea8694dc5aa@aaazen.com/
Fixes: 867046cc7027 ("minmax: relax check to allow comparison between unsigned arguments and signed constants")
Cc: stable@vger.kernel.org
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
 .../staging/media/atomisp/pci/sh_css_frac.h   | 26 ++++++++++++++-----
 1 file changed, 19 insertions(+), 7 deletions(-)

--
2.46.0

Comments

Hans de Goede Sept. 11, 2024, 6:03 p.m. UTC | #1 
Hi,

On 9/11/24 7:51 PM, Lorenzo Stoakes wrote:
> Avoid unnecessary nested min()/max() which results in egregious macro
> expansion. Use clamp_t() as this introduces the least possible expansion.
> 
> Not doing so results in an impact on build times.
> 
> This resolves an issue with slackware 15.0 32-bit compilation as reported
> by Richard Narron.
> 
> Presumably the min/max fixups would be difficult to backport, this patch
> should be easier and fix's Richard's problem in 5.15.
> 
> Reported-by: Richard Narron <richard@aaazen.com>
> Closes: https://lore.kernel.org/all/4a5321bd-b1f-1832-f0c-cea8694dc5aa@aaazen.com/
> Fixes: 867046cc7027 ("minmax: relax check to allow comparison between unsigned arguments and signed constants")
> Cc: stable@vger.kernel.org
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

Thanks, patch looks good to me:

Reviewed-by: Hans de Goede <hdegoede@redhat.com>

Regards,

Hans




> ---
>  .../staging/media/atomisp/pci/sh_css_frac.h   | 26 ++++++++++++++-----
>  1 file changed, 19 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/staging/media/atomisp/pci/sh_css_frac.h b/drivers/staging/media/atomisp/pci/sh_css_frac.h
> index b90b5b330dfa..8ba65161f7a9 100644
> --- a/drivers/staging/media/atomisp/pci/sh_css_frac.h
> +++ b/drivers/staging/media/atomisp/pci/sh_css_frac.h
> @@ -32,12 +32,24 @@
>  #define uISP_VAL_MAX		      ((unsigned int)((1 << uISP_REG_BIT) - 1))
> 
>  /* a:fraction bits for 16bit precision, b:fraction bits for ISP precision */
> -#define sDIGIT_FITTING(v, a, b) \
> -	min_t(int, max_t(int, (((v) >> sSHIFT) >> max(sFRACTION_BITS_FITTING(a) - (b), 0)), \
> -	  sISP_VAL_MIN), sISP_VAL_MAX)
> -#define uDIGIT_FITTING(v, a, b) \
> -	min((unsigned int)max((unsigned)(((v) >> uSHIFT) \
> -	>> max((int)(uFRACTION_BITS_FITTING(a) - (b)), 0)), \
> -	  uISP_VAL_MIN), uISP_VAL_MAX)
> +static inline int sDIGIT_FITTING(int v, int a, int b)
> +{
> +	int fit_shift = sFRACTION_BITS_FITTING(a) - b;
> +
> +	v >>= sSHIFT;
> +	v >>= fit_shift > 0 ? fit_shift : 0;
> +
> +	return clamp_t(int, v, sISP_VAL_MIN, sISP_VAL_MAX);
> +}
> +
> +static inline unsigned int uDIGIT_FITTING(unsigned int v, int a, int b)
> +{
> +	int fit_shift = uFRACTION_BITS_FITTING(a) - b;
> +
> +	v >>= uSHIFT;
> +	v >>= fit_shift > 0 ? fit_shift : 0;
> +
> +	return clamp_t(unsigned int, v, uISP_VAL_MIN, uISP_VAL_MAX);
> +}
> 
>  #endif /* __SH_CSS_FRAC_H */
> --
> 2.46.0
>
Linus Torvalds Sept. 11, 2024, 6:11 p.m. UTC | #2 
On Wed, 11 Sept 2024 at 10:51, Lorenzo Stoakes
<lorenzo.stoakes@oracle.com> wrote:
>
> Avoid unnecessary nested min()/max() which results in egregious macro
> expansion. Use clamp_t() as this introduces the least possible expansion.

I took this (single) patch directly, since that's the one that
actually causes build problems in limited environments (admittedly not
in current git with the more invasive min/max cleanups, but in order
to be back-ported).

Plus it cleans up the code with more legible inline functions, rather
than just doing some minimal syntactic changes. I expanded on the
commit message to say that.

The two others I'll leave for now and see what maintainers of their
respective areas think.

            Linus
diff mbox series

Patch

diff --git a/drivers/staging/media/atomisp/pci/sh_css_frac.h b/drivers/staging/media/atomisp/pci/sh_css_frac.h
index b90b5b330dfa..8ba65161f7a9 100644
--- a/drivers/staging/media/atomisp/pci/sh_css_frac.h
+++ b/drivers/staging/media/atomisp/pci/sh_css_frac.h
@@ -32,12 +32,24 @@ 
 #define uISP_VAL_MAX		      ((unsigned int)((1 << uISP_REG_BIT) - 1))

 /* a:fraction bits for 16bit precision, b:fraction bits for ISP precision */
-#define sDIGIT_FITTING(v, a, b) \
-	min_t(int, max_t(int, (((v) >> sSHIFT) >> max(sFRACTION_BITS_FITTING(a) - (b), 0)), \
-	  sISP_VAL_MIN), sISP_VAL_MAX)
-#define uDIGIT_FITTING(v, a, b) \
-	min((unsigned int)max((unsigned)(((v) >> uSHIFT) \
-	>> max((int)(uFRACTION_BITS_FITTING(a) - (b)), 0)), \
-	  uISP_VAL_MIN), uISP_VAL_MAX)
+static inline int sDIGIT_FITTING(int v, int a, int b)
+{
+	int fit_shift = sFRACTION_BITS_FITTING(a) - b;
+
+	v >>= sSHIFT;
+	v >>= fit_shift > 0 ? fit_shift : 0;
+
+	return clamp_t(int, v, sISP_VAL_MIN, sISP_VAL_MAX);
+}
+
+static inline unsigned int uDIGIT_FITTING(unsigned int v, int a, int b)
+{
+	int fit_shift = uFRACTION_BITS_FITTING(a) - b;
+
+	v >>= uSHIFT;
+	v >>= fit_shift > 0 ? fit_shift : 0;
+
+	return clamp_t(unsigned int, v, uISP_VAL_MIN, uISP_VAL_MAX);
+}

 #endif /* __SH_CSS_FRAC_H */