From cfd6fd5ad186dcb66d4014e811dc7d9a4f7348bc Mon Sep 17 00:00:00 2001
From: Scott Long <scottl@FreeBSD.org>
Date: Sun, 1 Oct 2017 15:35:21 +0000
Subject: [PATCH] Improve the debug parsing to allow flags to be added and
 subtracted from the existing set.

Submitted by:	rea@freebsd.org
---
 share/man/man4/mpr.4 |  5 +++++
 share/man/man4/mps.4 |  5 +++++
 sys/dev/mpr/mpr.c    | 30 +++++++++++++++++++++++++++++-
 sys/dev/mps/mps.c    | 31 ++++++++++++++++++++++++++++++-
 4 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/share/man/man4/mpr.4 b/share/man/man4/mpr.4
index 42069388a79..66846c8b516 100644
--- a/share/man/man4/mpr.4
+++ b/share/man/man4/mpr.4
@@ -354,6 +354,11 @@ All
 variables can be named by either an integer value or a text string.
 Multiple values can be specified together by either ORing the
 integer values or by providing a comma-separated list of names.
+A text string prefixed by
+.Qq +
+adds the specified debug levels to the existing set, while the prefix
+.Qq -
+removes them from the existing set.
 The current
 .Va debug_level
 status is reported in both formats for convenience.
diff --git a/share/man/man4/mps.4 b/share/man/man4/mps.4
index 0554541a6fd..efafccb9c46 100644
--- a/share/man/man4/mps.4
+++ b/share/man/man4/mps.4
@@ -330,6 +330,11 @@ All
 variables can be named by either an integer value or a text string.
 Multiple values can be specified together by either ORing the
 integer values or by providing a comma-separated list of names.
+A text string prefixed by
+.Qq +
+adds the specified debug levels to the existing set, while the prefix
+.Qq -
+removes them from the existing set.
 The current
 .Va debug_level
 status is reported in both formats for convenience.
diff --git a/sys/dev/mpr/mpr.c b/sys/dev/mpr/mpr.c
index 4f98ce12f0a..1a75707cbe3 100644
--- a/sys/dev/mpr/mpr.c
+++ b/sys/dev/mpr/mpr.c
@@ -1834,6 +1834,12 @@ static struct mpr_debug_string {
 	{"trace", MPR_TRACE}
 };
 
+enum mpr_debug_level_combiner {
+	COMB_NONE,
+	COMB_ADD,
+	COMB_SUB
+};
+
 static int
 mpr_debug_sysctl(SYSCTL_HANDLER_ARGS)
 {
@@ -1885,6 +1891,7 @@ static void
 mpr_parse_debug(struct mpr_softc *sc, char *list)
 {
 	struct mpr_debug_string *string;
+	enum mpr_debug_level_combiner op;
 	char *token, *endtoken;
 	size_t sz;
 	int flags, i;
@@ -1892,6 +1899,17 @@ mpr_parse_debug(struct mpr_softc *sc, char *list)
 	if (list == NULL || *list == '\0')
 		return;
 
+	if (*list == '+') {
+		op = COMB_ADD;
+		list++;
+	} else if (*list == '-') {
+		op = COMB_SUB;
+		list++;
+	} else
+		op = COMB_NONE;
+	if (*list == '\0')
+		return;
+
 	flags = 0;
 	sz = sizeof(mpr_debug_strings) / sizeof(mpr_debug_strings[0]);
 	while ((token = strsep(&list, ":,")) != NULL) {
@@ -1911,7 +1929,17 @@ mpr_parse_debug(struct mpr_softc *sc, char *list)
 		}
 	}
 
-	sc->mpr_debug = flags;
+	switch (op) {
+	case COMB_NONE:
+		sc->mpr_debug = flags;
+		break;
+	case COMB_ADD:
+		sc->mpr_debug |= flags;
+		break;
+	case COMB_SUB:
+		sc->mpr_debug &= (~flags);
+		break;
+	}
 	return;
 }
 
diff --git a/sys/dev/mps/mps.c b/sys/dev/mps/mps.c
index f2b7b121413..8bc461db3ab 100644
--- a/sys/dev/mps/mps.c
+++ b/sys/dev/mps/mps.c
@@ -1696,6 +1696,12 @@ static struct mps_debug_string {
 	{"trace", MPS_TRACE}
 };
 
+enum mps_debug_level_combiner {
+	COMB_NONE,
+	COMB_ADD,
+	COMB_SUB
+};
+
 static int
 mps_debug_sysctl(SYSCTL_HANDLER_ARGS)
 {
@@ -1747,6 +1753,7 @@ static void
 mps_parse_debug(struct mps_softc *sc, char *list)
 {
 	struct mps_debug_string *string;
+	enum mps_debug_level_combiner op;
 	char *token, *endtoken;
 	size_t sz;
 	int flags, i;
@@ -1754,6 +1761,17 @@ mps_parse_debug(struct mps_softc *sc, char *list)
 	if (list == NULL || *list == '\0')
 		return;
 
+	if (*list == '+') {
+		op = COMB_ADD;
+		list++;
+	} else if (*list == '-') {
+		op = COMB_SUB;
+		list++;
+	} else
+		op = COMB_NONE;
+	if (*list == '\0')
+		return;
+
 	flags = 0;
 	sz = sizeof(mps_debug_strings) / sizeof(mps_debug_strings[0]);
 	while ((token = strsep(&list, ":,")) != NULL) {
@@ -1773,7 +1791,18 @@ mps_parse_debug(struct mps_softc *sc, char *list)
 		}
 	}
 
-	sc->mps_debug = flags;
+	switch (op) {
+	case COMB_NONE:
+		sc->mps_debug = flags;
+		break;
+	case COMB_ADD:
+		sc->mps_debug |= flags;
+		break;
+	case COMB_SUB:
+		sc->mps_debug &= (~flags);
+		break;
+	}
+
 	return;
 }