[PATCH 15/16] dyndbg: allow inverted-flag-chars in modflags

From: Jim Cromie
Date: Wed Nov 27 2019 - 12:51:57 EST


Extend flags modifications to allow [PFMLT_XYZ] inverted flags.
This allows control-queries like:

#> Q () { echo file inode.c $* > control } # to type less
#> Q -P # same as +p
#> Q +X # same as -x
#> Q xyz-P # same as xyz+p

This allows flags in a callsite to be simultaneously set and cleared,
while still starting with the current flagstate (with +- ops).
Generally, you chose -p or +p 1st, then set or clear flags
accordingly.

# enable print on callsites with 'xy'; and re-mark with just 'z'
#> Q xy+pXYz

Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
Documentation/admin-guide/dynamic-debug-howto.rst | 8 +++++---
lib/dynamic_debug.c | 6 ++++--
2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 5404e23eeac8..493e74a14bdd 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -250,9 +250,11 @@ only callsites with x&y cleared.

Flagsets cannot contain ``xX`` etc, a flag cannot be true and false.

-modflags containing upper-case flags is reserved/undefined for now.
-inverted-flags are currently ignored, usage gets trickier if given
-``-pXy``, it should leave x set.
+modflags may contain upper-case flags also, using these lets you
+invert the flag setting implied by the OP; '-pX' means disable
+printing, and mark that callsite with usr-x flag to create a group,
+for optional further manipulation. Generally, '+p' and '-p' is your
+main choice, and use of inverted flags in modflags is rare.

Notes::

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index b2630df0c3a5..82daf95b8f64 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -488,15 +488,17 @@ static int ddebug_parse_flags(const char *str,

/* calculate final mods: flags, mask based upon op */
switch (op) {
+ unsigned int tmp;
case '=':
mods->mask = 0;
break;
case '+':
- mods->mask = ~0U;
+ mods->mask = ~mods->mask;
break;
case '-':
+ tmp = mods->mask;
mods->mask = ~mods->flags;
- mods->flags = 0;
+ mods->flags = tmp;
break;
}

--
2.23.0