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

From: Jim Cromie
Date: Fri Jun 05 2020 - 12:28:41 EST


Extend flags modifications to allow [PFMLTU] negating flags.
This allows control-queries like:

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

Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
Documentation/admin-guide/dynamic-debug-howto.rst | 10 ++++++----
lib/dynamic_debug.c | 6 ++++--
2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 26a19f511afa..45470c9f0dad 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -252,9 +252,11 @@ only callsites with ``u`` and ``f`` cleared.

Flagsets cannot contain ``pP`` 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; '-pU' means disable
+printing, and mark that callsite with the user-flag to create a group,
+for optional further manipulation. Generally, '+p' and '-p' is your
+main choice, and use of negating flags in modflags is rare.

Notes::

@@ -264,7 +266,7 @@ For ``print_hex_dump_debug()`` and ``print_hex_dump_bytes()``, only
For display, the flags are preceded by ``=``
(mnemonic: what the flags are currently equal to).

-Note the regexp ``^[-+=][flmptu_]+$`` matches a flags specification.
+Note the regexp ``/^[-+=][flmptu_]+$/i`` matches a flags specification.
To clear all flags at once, use ``=_`` or ``-flmptu``.


diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index ee92e93cf23d..63ae6f77a0e4 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -485,15 +485,17 @@ 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;
}

--
2.26.2