x86/cpufeature: Fix various quality problems in the <asm/cpu_device_hd.h> header

Ingo Molnar · Ingo Molnar · commit 266d63a7d9d4 · 2019-02-11T12:36:24.000+01:00
Thomas noticed that the new arch/x86/include/asm/cpu_device_id.h header is
a train-wreck that didn't incorporate review feedback like not using __u8
in kernel-only headers.

While at it also fix all the *other* problems this header has:

 - Use canonical names for the header guards. It's inexplicable why a non-standard
   guard was used.

 - Don't define the header guard to 1. Plus annotate the closing #endif as done
   absolutely every other header. Again, an inexplicable source of noise.

 - Move the kernel API calls provided by this header next to each other, there's
   absolutely no reason to have them spread apart in the header.

 - Align the INTEL_CPU_DESC() macro initializations vertically, this is easier to
   read and it's also the canonical style.

 - Actually name the macro arguments properly: instead of 'mod, step, rev',
   spell out 'model, stepping, revision' - it's not like we have a lack of
   characters in this header.

 - Actually make arguments macro-safe - again it's inexplicable why it wasn't
   done properly to begin with.

Quite amazing how many problems a 41 lines header can contain.

This kind of code quality is unacceptable, and it slipped through the
review net of 2 developers and 2 maintainers, including myself, until
Thomas noticed it. :-/

Reported-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Kan Liang &lt;kan.liang@linux.intel.com&gt;
Cc: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
diff --git a/arch/x86/include/asm/cpu_device_id.h b/arch/x86/include/asm/cpu_device_id.h
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _CPU_DEVICE_ID
-#define _CPU_DEVICE_ID 1
+#ifndef _ASM_X86_CPU_DEVICE_ID
+#define _ASM_X86_CPU_DEVICE_ID
 
 /*
  * Declare drivers belonging to specific x86 CPUs
@@ -9,8 +9,6 @@
 
 #include <linux/mod_devicetable.h>
 
-extern const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match);
-
 /*
  * Match specific microcode revisions.
  *
@@ -22,21 +20,22 @@ extern const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match);
  */
 
 struct x86_cpu_desc {
-	__u8	x86_family;
-	__u8	x86_vendor;
-	__u8	x86_model;
-	__u8	x86_stepping;
-	__u32	x86_microcode_rev;
+	u8	x86_family;
+	u8	x86_vendor;
+	u8	x86_model;
+	u8	x86_stepping;
+	u32	x86_microcode_rev;
 };
 
-#define INTEL_CPU_DESC(mod, step, rev) {			\
-	.x86_family = 6,					\
-	.x86_vendor = X86_VENDOR_INTEL,				\
-	.x86_model = mod,					\
-	.x86_stepping = step,					\
-	.x86_microcode_rev = rev,				\
+#define INTEL_CPU_DESC(model, stepping, revision) {		\
+	.x86_family		= 6,				\
+	.x86_vendor		= X86_VENDOR_INTEL,		\
+	.x86_model		= (model),			\
+	.x86_stepping		= (stepping),			\
+	.x86_microcode_rev	= (revision),			\
 }
 
+extern const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match);
 extern bool x86_cpu_has_min_microcode_rev(const struct x86_cpu_desc *table);
 
-#endif
+#endif /* _ASM_X86_CPU_DEVICE_ID */
