[RFC 01/11] mm: debug: format flags in a buffer

[Sasha Levin]

Format various flags to a string buffer rather than printing them. This is
a helper for later.

Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
 mm/debug.c |   35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/mm/debug.c b/mm/debug.c
index 3eb3ac2..c9f7dd7 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -80,6 +80,41 @@ static void dump_flags(unsigned long flags,
 	pr_cont(")\n");
 }
 
+static char *format_flags(unsigned long flags,
+			const struct trace_print_flags *names, int count,
+			char *buf, char *end)
+{
+	const char *delim = "";
+	unsigned long mask;
+	int i;
+
+	buf += snprintf(buf, (buf > end ? 0 : end - buf),
+				"flags: %#lx(", flags);
+
+	/* remove zone id */
+	flags &= (1UL << NR_PAGEFLAGS) - 1;
+
+	for (i = 0; i < count && flags; i++) {
+                mask = names[i].mask;
+                if ((flags & mask) != mask)
+                        continue;
+
+                flags &= ~mask;
+		buf += snprintf(buf, (buf > end ? 0 : end - buf),
+                		"%s%s", delim, names[i].name);
+                delim = "|";
+        }
+
+        /* check for left over flags */
+        if (flags)
+		buf += snprintf(buf, (buf > end ? 0 : end - buf),
+                		"%s%#lx", delim, flags);
+
+	buf += snprintf(buf, (buf > end ? 0 : end - buf), ")\n");
+
+	return buf;
+}
+
 void dump_page_badflags(struct page *page, const char *reason,
 		unsigned long badflags)
 {
-- 
1.7.10.4

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