Index: share/man/man9/Makefile
===================================================================
--- share/man/man9/Makefile
+++ share/man/man9/Makefile
@@ -972,6 +972,7 @@
 MLINKS+=dev_refthread.9 devvn_refthread.9 \
 	dev_refthread.9 dev_relthread.9
 MLINKS+=devctl_notify.9 devctl_notifyf.9
+MLINKS+=devctl_safe_quote_sb.9 devctl_safe_quote_sb_len.9
 MLINKS+=devfs_set_cdevpriv.9 devfs_clear_cdevpriv.9 \
 	devfs_set_cdevpriv.9 devfs_get_cdevpriv.9
 MLINKS+=device_add_child.9 device_add_child_ordered.9
Index: share/man/man9/devctl_safe_quote_sb.9
===================================================================
--- share/man/man9/devctl_safe_quote_sb.9
+++ share/man/man9/devctl_safe_quote_sb.9
@@ -23,17 +23,20 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 22, 2020
+.Dd March 12, 2022
 .Dt DEVCTL_SAFE_QUOTE_SB 9
 .Os
 .Sh NAME
-.Nm devctl_safe_quote_sb
+.Nm devctl_safe_quote_sb ,
+.Nm devctl_safe_quote_sb_len
 .Nd Insert a string, properly quoted, into a sbuf
 .Sh SYNOPSIS
 .In sys/devctl.h
 .In sys/sbuf.h
 .Ft void
 .Fn devctl_safe_quote_sb "struct sbuf *sb" "const char *src"
+.Ft void
+.Fn devctl_safe_quote_sb_len "struct sbuf *sb" "const char *src" "size_t len"
 .Sh DESCRIPTION
 Copy the string from
 .Va src
@@ -46,8 +49,15 @@
 All other characters are copied without modification.
 The
 .Xr devctl 4
-protocol requires quoted string to be quoted thus.
+protocol requires a quoted string to have these special characters escaped.
 This routine centralizes this knowledge.
+.Pp
+The
+.Fn devctl_safe_quote_sb_len
+will limit escaping to the first
+.Fa len
+characters of
+.Va src .
 .Sh SEE ALSO
 .Xr devd 8
 .Sh AUTHORS
Index: sys/kern/subr_bus.c
===================================================================
--- sys/kern/subr_bus.c
+++ sys/kern/subr_bus.c
@@ -878,6 +878,30 @@
 	}
 }
 
+/**
+ * @brief safely quotes strings that might have double quotes in them.
+ *
+ * The devctl protocol relies on quoted strings having matching quotes.
+ * This routine quotes any internal quotes so the resulting string
+ * is safe to pass to snprintf to construct, for example pnp info strings.
+ *
+ * @param sb	sbuf to place the characters into
+ * @param src	Original buffer.
+ * @param len	Max length of the buffer to process.
+ */
+void
+devctl_safe_quote_sb_len(struct sbuf *sb, const char *src, size_t len)
+{
+	const char *srcp;
+
+	srcp = src;
+	while (*srcp != '\0' && (srcp - src) != len) {
+		if (*srcp == '"' || *srcp == '\\')
+			sbuf_putc(sb, '\\');
+		sbuf_putc(sb, *srcp++);
+	}
+}
+
 /* End of /dev/devctl code */
 
 static struct device_list bus_data_devices;
Index: sys/sys/devctl.h
===================================================================
--- sys/sys/devctl.h
+++ sys/sys/devctl.h
@@ -19,6 +19,7 @@
     const char *__type, const char *__data);
 struct sbuf;
 void devctl_safe_quote_sb(struct sbuf *__sb, const char *__src);
+void devctl_safe_quote_sb_len(struct sbuf *sb, const char *src, size_t len);
 #endif
 
 #endif /* _SYS_DEVCTL_H_ */