linux-kernel - [PATCH v2 3/5] sound: query dynamic DEBUG

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Date:	Thu, 11 Feb 2016 13:04:59 +0900
From:	js1304@...il.com
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	David Rientjes <rientjes@...gle.com>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Takashi Iwai <tiwai@...e.com>,
	Chris Metcalf <cmetcalf@...hip.com>,
	Christoph Lameter <cl@...ux.com>, linux-api@...r.kernel.org,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: [PATCH v2 3/5] sound: query dynamic DEBUG_PAGEALLOC setting

From: Joonsoo Kim <iamjoonsoo.kim@....com>

We can disable debug_pagealloc processing even if the code is compiled
with CONFIG_DEBUG_PAGEALLOC. This patch changes the code to query
whether it is enabled or not in runtime.

v2: export _debug_pagealloc_enabled to modules, per Andrew.

Acked-by: David Rientjes <rientjes@...gle.com>
Acked-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
---
 mm/page_alloc.c           | 1 +
 sound/drivers/pcsp/pcsp.c | 9 +++++----
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 87b3e2f..00118fe 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -498,6 +498,7 @@ void prep_compound_page(struct page *page, unsigned int order)
 unsigned int _debug_guardpage_minorder;
 bool _debug_pagealloc_enabled __read_mostly
 			= IS_ENABLED(CONFIG_DEBUG_PAGEALLOC_ENABLE_DEFAULT);
+EXPORT_SYMBOL(_debug_pagealloc_enabled);
 bool _debug_guardpage_enabled __read_mostly;
 
 static int __init early_debug_pagealloc(char *buf)
diff --git a/sound/drivers/pcsp/pcsp.c b/sound/drivers/pcsp/pcsp.c
index 27e25bb..72e2d00 100644
--- a/sound/drivers/pcsp/pcsp.c
+++ b/sound/drivers/pcsp/pcsp.c
@@ -14,6 +14,7 @@
 #include <linux/input.h>
 #include <linux/delay.h>
 #include <linux/bitops.h>
+#include <linux/mm.h>
 #include "pcsp_input.h"
 #include "pcsp.h"
 
@@ -148,11 +149,11 @@ static int alsa_card_pcsp_init(struct device *dev)
 		return err;
 	}
 
-#ifdef CONFIG_DEBUG_PAGEALLOC
 	/* Well, CONFIG_DEBUG_PAGEALLOC makes the sound horrible. Lets alert */
-	printk(KERN_WARNING "PCSP: CONFIG_DEBUG_PAGEALLOC is enabled, "
-	       "which may make the sound noisy.\n");
-#endif
+	if (debug_pagealloc_enabled()) {
+		printk(KERN_WARNING "PCSP: CONFIG_DEBUG_PAGEALLOC is enabled, "
+		       "which may make the sound noisy.\n");
+	}
 
 	return 0;
 }
-- 
1.9.1