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[firefly-linux-kernel-4.4.55.git] / lib / kasprintf.c

diff --git a/lib/kasprintf.c b/lib/kasprintf.c
index 32f12150fc4f4a82aace1ff42afc17969f8692a3..f194e6e593e19db22ad6b7e50aeee0e7c46eafa6 100644 (file)
--- a/lib/kasprintf.c
+++ b/lib/kasprintf.c
@@ -31,6 +31,22 @@ char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap)
 }
 EXPORT_SYMBOL(kvasprintf);
 
+/*
+ * If fmt contains no % (or is exactly %s), use kstrdup_const. If fmt
+ * (or the sole vararg) points to rodata, we will then save a memory
+ * allocation and string copy. In any case, the return value should be
+ * freed using kfree_const().
+ */
+const char *kvasprintf_const(gfp_t gfp, const char *fmt, va_list ap)
+{
+       if (!strchr(fmt, '%'))
+               return kstrdup_const(fmt, gfp);
+       if (!strcmp(fmt, "%s"))
+               return kstrdup_const(va_arg(ap, const char*), gfp);
+       return kvasprintf(gfp, fmt, ap);
+}
+EXPORT_SYMBOL(kvasprintf_const);
+
 char *kasprintf(gfp_t gfp, const char *fmt, ...)
 {
        va_list ap;