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Message-Id: <20200613155738.2249399-18-jim.cromie@gmail.com>
Date: Sat, 13 Jun 2020 09:57:31 -0600
From: Jim Cromie <jim.cromie@...il.com>
To: jbaron@...mai.com, linux-kernel@...r.kernel.org,
akpm@...uxfoundation.org, gregkh@...uxfoundation.org
Cc: linux@...musvillemoes.dk, Jim Cromie <jim.cromie@...il.com>,
Jonathan Corbet <corbet@....net>,
Andrew Morton <akpm@...ux-foundation.org>,
Petr Mladek <pmladek@...e.com>, Will Deacon <will@...nel.org>,
Orson Zhai <orson.zhai@...soc.com>, linux-doc@...r.kernel.org
Subject: [PATCH v2 17/24] dyndbg: add user-flag, negating-flags, and filtering on flags
1. Add a user-flag [u] which works like the [pfmlt] flags, but has no
effect on callsite behavior; it allows incremental marking of
arbitrary sets of callsites.
2. Add [PFMLTU] flags, which negate their counterparts; P===!p etc.
And in ddebug_read_flags():
current code does: [pfmltu_] -> flags
copy it to: [PFMLTU_] -> mask
also disallow both of a pair: ie no 'pP', no true & false.
3. Add filtering ops into ddebug_change(), right after all the
callsite-property selections are complete. These filter on the
callsite's current flagstate before applying modflags.
Why ?
The 'u' flag lets the user assemble an arbitary set of callsites.
Then using filter flags, user can activate the 'u' set.
#> echo 'file foo.c +u; file bar.c +u' > control # and repeat
#> echo 'u+p' > control
Using negating-flags in your filter-flags, you can completely specify
the matching flagstate; not just required flags, but also prohibited
flags.
The user flag isn't strictly needed, but with it you can avoid using
[fmlt] flags for marking, which would alter logging when enabled.
---
.../admin-guide/dynamic-debug-howto.rst | 31 ++++++++++++++++---
include/linux/dynamic_debug.h | 1 +
lib/dynamic_debug.c | 31 ++++++++++++++-----
3 files changed, 51 insertions(+), 12 deletions(-)
diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
index 4f343e6036f5..45d3adf889ba 100644
--- a/Documentation/admin-guide/dynamic-debug-howto.rst
+++ b/Documentation/admin-guide/dynamic-debug-howto.rst
@@ -238,16 +238,39 @@ The flags are::
l Include line number in the printed message
m Include module name in the printed message
t Include thread ID in messages not generated from interrupt context
+ u user flag, to mark callsites into a group
_ No flags are set. (Or'd with others on input)
-For ``print_hex_dump_debug()`` and ``print_hex_dump_bytes()``, only ``p`` flag
-have meaning, other flags ignored.
+Additionally, the flag-chars ``[pflmtu]`` have negating flag-chars
+``[PFMLTU]``, which invert the meanings above. Their use follows.
+
+Using Filters::
+
+Filter-flags specify an optional additional selector on pr_debug
+callsites; with them you can compose an arbitrary set of callsites, by
+iteratively marking them with ``+u``, then enabling them all with
+``u+p``. You can also use ``fmlt`` flags for this, unless the format
+changes are inconvenient.
+
+Filters can also contain the negating flags, like ``UF``, which select
+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.
+
+Notes::
+
+For ``print_hex_dump_debug()`` and ``print_hex_dump_bytes()``, only
+``p`` flag has meaning, other flags are ignored.
For display, the flags are preceded by ``=``
(mnemonic: what the flags are currently equal to).
-Note the regexp ``^[-+=][flmpt_]+$`` matches a flags specification.
-To clear all flags at once, use ``=_`` or ``-flmpt``.
+Note the regexp ``^[-+=][flmptu_]+$`` matches a flags specification.
+To clear all flags at once, use ``=_`` or ``-flmptu``.
Debug messages during Boot Process
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index aa9ff9e1c0b3..59960a8dd9f9 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -32,6 +32,7 @@ struct _ddebug {
#define _DPRINTK_FLAGS_INCL_FUNCNAME (1<<2)
#define _DPRINTK_FLAGS_INCL_LINENO (1<<3)
#define _DPRINTK_FLAGS_INCL_TID (1<<4)
+#define _DPRINTK_FLAGS_USR (1<<5)
#if defined DEBUG
#define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT
#else
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index b3c262c009d2..b02cde1cfc2f 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -83,13 +83,14 @@ static inline const char *trim_prefix(const char *path)
return path + skip;
}
-static struct { unsigned flag:8; char opt_char; } opt_array[] = {
- { _DPRINTK_FLAGS_PRINT, 'p' },
- { _DPRINTK_FLAGS_INCL_MODNAME, 'm' },
- { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
- { _DPRINTK_FLAGS_INCL_LINENO, 'l' },
- { _DPRINTK_FLAGS_INCL_TID, 't' },
- { _DPRINTK_FLAGS_NONE, '_' },
+static struct { unsigned flag:8; char opt_char, not_char; } opt_array[] = {
+ { _DPRINTK_FLAGS_PRINT, 'p', 'P' },
+ { _DPRINTK_FLAGS_INCL_MODNAME, 'm', 'M' },
+ { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f', 'F' },
+ { _DPRINTK_FLAGS_INCL_LINENO, 'l', 'L' },
+ { _DPRINTK_FLAGS_INCL_TID, 't', 'T' },
+ { _DPRINTK_FLAGS_NONE, '_', '_' },
+ { _DPRINTK_FLAGS_USR, 'u', 'U' },
};
struct flagsbuf { char buf[ARRAY_SIZE(opt_array)+1]; };
@@ -195,6 +196,13 @@ static int ddebug_change(const struct ddebug_query *query,
dp->lineno > query->last_lineno)
continue;
+ /* filter for required flags */
+ if ((dp->flags & filter->flags) != filter->flags)
+ continue;
+ /* filter on prohibited bits */
+ if ((~dp->flags & filter->mask) != filter->mask)
+ continue;
+
nfound++;
newflags = (dp->flags & mods->mask) | mods->flags;
@@ -428,10 +436,17 @@ static int ddebug_read_flags(const char *str, struct flagsettings *f)
if (*str == opt_array[i].opt_char) {
f->flags |= opt_array[i].flag;
break;
+ } else if (*str == opt_array[i].not_char) {
+ f->mask |= opt_array[i].flag;
+ break;
}
}
if (i < 0) {
- pr_err("unknown flag '%c' in \"%s\"\n", *str, str);
+ pr_err("unknown flag '%c'", *str);
+ return -EINVAL;
+ }
+ if (f->flags & f->mask) {
+ pr_err("flag '%c' conflicts with previous\n", *str);
return -EINVAL;
}
}
--
2.26.2
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