linux-kernel - [PATCH] acpi: avoid -Wempty-body warnings

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Date:   Mon, 22 Mar 2021 11:58:00 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Robert Moore <robert.moore@...el.com>,
        Erik Kaneda <erik.kaneda@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Len Brown <lenb@...nel.org>
Cc:     Arnd Bergmann <arnd@...db.de>, linux-acpi@...r.kernel.org,
        devel@...ica.org, linux-kernel@...r.kernel.org
Subject: [PATCH] acpi: avoid -Wempty-body warnings

From: Arnd Bergmann <arnd@...db.de>

The acpi drivers produce a number of avoidable warnings for empty macros
when building with 'make W=1':

drivers/acpi/acpi_processor.c: In function 'acpi_processor_errata_piix4':
drivers/acpi/acpi_processor.c:133:95: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
  133 |                                   "Bus master activity detection (BM-IDE) erratum enabled\n"));
      |                                                                                               ^
drivers/acpi/acpi_processor.c:136:82: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
  136 |                                   "Type-F DMA livelock erratum (C3 disabled)\n"));
      |                                                                                  ^
drivers/acpi/acpi_processor.c: In function 'acpi_processor_get_info':
drivers/acpi/acpi_processor.c:251:77: error: suggest braces around empty body in an 'else' statement [-Werror=empty-body]
  251 |                                   "No bus mastering arbitration control\n"));
      |                                                                             ^
drivers/acpi/processor_pdc.c: In function 'acpi_processor_eval_pdc':
drivers/acpi/processor_pdc.c:136:79: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
  136 |                     "Could not evaluate _PDC, using legacy perf. control.\n"));
      |                                                                               ^

I tried making these call no_printk() instead, which would add proper
format string checking, but that turned out to be a rather invasive
change, so just shut up the warning by turning the macros into empty
"do {} while (0)" statements.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 include/acpi/acoutput.h | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/include/acpi/acoutput.h b/include/acpi/acoutput.h
index 1538a6853822..b5484ef31f27 100644
--- a/include/acpi/acoutput.h
+++ b/include/acpi/acoutput.h
@@ -433,23 +433,23 @@
  * This is the non-debug case -- make everything go away,
  * leaving no executable debug code!
  */
-#define ACPI_DEBUG_PRINT(pl)
-#define ACPI_DEBUG_PRINT_RAW(pl)
-#define ACPI_DEBUG_EXEC(a)
-#define ACPI_DEBUG_ONLY_MEMBERS(a)
-#define ACPI_FUNCTION_NAME(a)
-#define ACPI_FUNCTION_TRACE(a)
-#define ACPI_FUNCTION_TRACE_PTR(a, b)
-#define ACPI_FUNCTION_TRACE_U32(a, b)
-#define ACPI_FUNCTION_TRACE_STR(a, b)
-#define ACPI_FUNCTION_ENTRY()
-#define ACPI_DUMP_STACK_ENTRY(a)
-#define ACPI_DUMP_OPERANDS(a, b, c)
-#define ACPI_DUMP_ENTRY(a, b)
-#define ACPI_DUMP_PATHNAME(a, b, c, d)
-#define ACPI_DUMP_BUFFER(a, b)
+#define ACPI_DEBUG_PRINT(pl)			do { } while (0)
+#define ACPI_DEBUG_PRINT_RAW(pl)		do { } while (0)
+#define ACPI_DEBUG_EXEC(a)			do { } while (0)
+#define ACPI_DEBUG_ONLY_MEMBERS(a)		do { } while (0)
+#define ACPI_FUNCTION_NAME(a)			do { } while (0)
+#define ACPI_FUNCTION_TRACE(a)			do { } while (0)
+#define ACPI_FUNCTION_TRACE_PTR(a, b)		do { } while (0)
+#define ACPI_FUNCTION_TRACE_U32(a, b)		do { } while (0)
+#define ACPI_FUNCTION_TRACE_STR(a, b)		do { } while (0)
+#define ACPI_FUNCTION_ENTRY()			do { } while (0)
+#define ACPI_DUMP_STACK_ENTRY(a)		do { } while (0)
+#define ACPI_DUMP_OPERANDS(a, b, c)		do { } while (0)
+#define ACPI_DUMP_ENTRY(a, b)			do { } while (0)
+#define ACPI_DUMP_PATHNAME(a, b, c, d)		do { } while (0)
+#define ACPI_DUMP_BUFFER(a, b)			do { } while (0)
 #define ACPI_IS_DEBUG_ENABLED(level, component) 0
-#define ACPI_TRACE_POINT(a, b, c, d)
+#define ACPI_TRACE_POINT(a, b, c, d)		do { } while (0)
 
 /* Return macros must have a return statement at the minimum */
 
-- 
2.29.2