linux-kernel - Re: [PATCH 8/8] x86/platform/uv: Account for UV Hubless in is_uvX

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Date:   Tue, 3 Sep 2019 23:52:46 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Mike Travis <mike.travis@....com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Borislav Petkov <bp@...en8.de>,
        Dimitri Sivanich <dimitri.sivanich@....com>,
        Russ Anderson <russ.anderson@....com>,
        Hedi Berriche <hedi.berriche@....com>,
        Steve Wahl <steve.wahl@....com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH 8/8] x86/platform/uv: Account for UV Hubless in
 is_uvX_hub Ops

On Tue, Sep 03, 2019 at 11:58:49AM -0700, Mike Travis wrote:
> Those ifdefs are not dead code and are being actively used.  Plus UV1
> support is dead and I think the last running system died about a year ago
> and no support or parts are available.  So undef'ing these macros will
> simplify and reduce the size of the object code.

I'm not complaining about removing some ifdefs, that is always good.
I complain about keeping the others that are dead.  And if Hub 1 is
dead please drop all the checks and support code for it.

A patch against current mainline to show what I mean is below.

---
>From e84506399fa9436d47b33491d3e38e9dc3c718c7 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@....de>
Date: Tue, 3 Sep 2019 18:05:37 +0200
Subject: x86/uv: Remove the dead UV?_HUB_IS_SUPPORTED defines

These are always set, so remove them and the dead code for the case
where they are not defined.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 arch/x86/include/asm/uv/uv_hub.h  | 38 -------------------------------
 arch/x86/include/asm/uv/uv_mmrs.h |  7 ------
 2 files changed, 45 deletions(-)

diff --git a/arch/x86/include/asm/uv/uv_hub.h b/arch/x86/include/asm/uv/uv_hub.h
index 6eed0b379412..f71eb659f0de 100644
--- a/arch/x86/include/asm/uv/uv_hub.h
+++ b/arch/x86/include/asm/uv/uv_hub.h
@@ -229,68 +229,33 @@ static inline struct uv_hub_info_s *uv_cpu_hub_info(int cpu)
 #define UV4_HUB_REVISION_BASE		7
 #define UV4A_HUB_REVISION_BASE		8	/* UV4 (fixed) rev 2 */
 
-#ifdef	UV1_HUB_IS_SUPPORTED
 static inline int is_uv1_hub(void)
 {
 	return uv_hub_info->hub_revision < UV2_HUB_REVISION_BASE;
 }
-#else
-static inline int is_uv1_hub(void)
-{
-	return 0;
-}
-#endif
 
-#ifdef	UV2_HUB_IS_SUPPORTED
 static inline int is_uv2_hub(void)
 {
 	return ((uv_hub_info->hub_revision >= UV2_HUB_REVISION_BASE) &&
 		(uv_hub_info->hub_revision < UV3_HUB_REVISION_BASE));
 }
-#else
-static inline int is_uv2_hub(void)
-{
-	return 0;
-}
-#endif
 
-#ifdef	UV3_HUB_IS_SUPPORTED
 static inline int is_uv3_hub(void)
 {
 	return ((uv_hub_info->hub_revision >= UV3_HUB_REVISION_BASE) &&
 		(uv_hub_info->hub_revision < UV4_HUB_REVISION_BASE));
 }
-#else
-static inline int is_uv3_hub(void)
-{
-	return 0;
-}
-#endif
 
 /* First test "is UV4A", then "is UV4" */
-#ifdef	UV4A_HUB_IS_SUPPORTED
 static inline int is_uv4a_hub(void)
 {
 	return (uv_hub_info->hub_revision >= UV4A_HUB_REVISION_BASE);
 }
-#else
-static inline int is_uv4a_hub(void)
-{
-	return 0;
-}
-#endif
 
-#ifdef	UV4_HUB_IS_SUPPORTED
 static inline int is_uv4_hub(void)
 {
 	return uv_hub_info->hub_revision >= UV4_HUB_REVISION_BASE;
 }
-#else
-static inline int is_uv4_hub(void)
-{
-	return 0;
-}
-#endif
 
 static inline int is_uvx_hub(void)
 {
@@ -302,10 +267,7 @@ static inline int is_uvx_hub(void)
 
 static inline int is_uv_hub(void)
 {
-#ifdef	UV1_HUB_IS_SUPPORTED
 	return uv_hub_info->hub_revision;
-#endif
-	return is_uvx_hub();
 }
 
 union uvh_apicid {
diff --git a/arch/x86/include/asm/uv/uv_mmrs.h b/arch/x86/include/asm/uv/uv_mmrs.h
index 62c79e26a59a..9ee5ed6e8b34 100644
--- a/arch/x86/include/asm/uv/uv_mmrs.h
+++ b/arch/x86/include/asm/uv/uv_mmrs.h
@@ -99,13 +99,6 @@
 #define UV3_HUB_PART_NUMBER_X	0x4321
 #define UV4_HUB_PART_NUMBER	0x99a1
 
-/* Compat: Indicate which UV Hubs are supported. */
-#define UV1_HUB_IS_SUPPORTED	1
-#define UV2_HUB_IS_SUPPORTED	1
-#define UV3_HUB_IS_SUPPORTED	1
-#define UV4_HUB_IS_SUPPORTED	1
-#define UV4A_HUB_IS_SUPPORTED	1
-
 /* Error function to catch undefined references */
 extern unsigned long uv_undefined(char *str);
 
-- 
2.20.1