From: Jim Cromie <jim.cromie@gmail.com>
To: jbaron@akamai.com, gregkh@linuxfoundation.org,
linux-kernel@vger.kernel.org
Cc: Jim Cromie <jim.cromie@gmail.com>
Subject: [RFC PATCH v2 12/19] dyndbg: allow deleting site info via control interface
Date: Fri, 25 Dec 2020 13:19:37 -0700 [thread overview]
Message-ID: <20201225201944.3701590-13-jim.cromie@gmail.com> (raw)
In-Reply-To: <20201225201944.3701590-1-jim.cromie@gmail.com>
Allow users & subsystems to selectively delete callsite info for
individual pr-debug callsites, or groups of them.
Its purpose is for subsystems such as DRM which:
- use distinct categories for logging, and can map them over to a
format prefix, like: "drm:core:", "drm:kms:", etc.
- are happy with group control of all the callsites in a class/cateory.
individual control is still possible using queries including line numbers
- don't need dynamic "module:function:line:" prefixes in log messages
- don't care about loss of context in /proc/dynamic_debug/control
before:
init/initramfs.c:485 [initramfs]unpack_to_rootfs =_ "Detected %s compressed data\012"
init/main.c:1337 [main]run_init_process =pm " %s\012"
init/main.c:1335 [main]run_init_process =pm " with environment:\012"
init/main.c:1334 [main]run_init_process =pm " %s\012"
init/main.c:1332 [main]run_init_process =pm " with arguments:\012"
init/main.c:1121 [main]initcall_blacklisted =pm "initcall %s blacklisted\012"
init/main.c:1082 [main]initcall_blacklist =pm "blacklisting initcall %s\012"
then:
bash-5.0# echo file init/main.c +D > /proc/dynamic_debug/control
after:
init/initramfs.c:485 [initramfs]unpack_to_rootfs =_ "Detected %s compressed data\012"
[main]:1337 =pmD " %s\012"
[main]:1335 =pmD " with environment:\012"
[main]:1334 =pmD " %s\012"
[main]:1332 =pmD " with arguments:\012"
[main]:1121 =pmD "initcall %s blacklisted\012"
[main]:1082 =pmD "blacklisting initcall %s\012"
Notes:
If Drm adopted dyndbg, i915 + drm* would add ~1600 prdebugs, amdgpu +
drm* would add ~3200 callsites, so the additional memory costs are
substantial. In trade, drm and drivers would avoid lots of calls to
drm_debug_enabled(). This patch should reduce the costs.
Using this interface, drm could drop site info for all categories /
prefixes controlled by bits in drm.debug, while preserving site info
and individual selectivity for any uncategorized prdebugs.
Lastly, because lineno field was not moved into _ddebug_callsite, it
can be used to modify a single[*] callsite even if drm has dropped all
the callsite data:
echo module $mod format ^$prefix line $line +p >control
Dropping a _callsite a one-way, information losing operation, so minor
misuse is possible. Worst case is maybe (depending upon previous
settings) some loss of logging context/decorations.
echo +D > /proc/dynamic_debug/control
[*] amdgpu has some macros invoking clusters of pr_debugs; each use of
them creates a cluster of pr-debugs with the same line number.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
include/linux/dynamic_debug.h | 1 +
lib/dynamic_debug.c | 9 +++++++++
2 files changed, 10 insertions(+)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index ea07a91a43bc..49fa1390d1f8 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -40,6 +40,7 @@ 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_DELETE_SITE (1<<7) /* drop site info to save ram */
#define _DPRINTK_FLAGS_INCL_ANYSITE \
(_DPRINTK_FLAGS_INCL_MODNAME \
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 6203a6ad1706..2d10fc1e16cd 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -90,6 +90,7 @@ static struct { unsigned flag:8; char opt_char; } opt_array[] = {
{ _DPRINTK_FLAGS_INCL_LINENO, 'l' },
{ _DPRINTK_FLAGS_INCL_TID, 't' },
{ _DPRINTK_FLAGS_NONE, '_' },
+ { _DPRINTK_FLAGS_DELETE_SITE, 'D' },
};
struct flagsbuf { char buf[ARRAY_SIZE(opt_array)+1]; };
@@ -198,6 +199,14 @@ static inline void ddebug_alter_site(struct _ddebug *dp,
} else if (modifiers->flags & _DPRINTK_FLAGS_PRINT)
static_branch_enable(&dp->key.dd_key_true);
#endif
+ /* delete site info for this callsite */
+ if (modifiers->flags & _DPRINTK_FLAGS_DELETE_SITE) {
+ if (dp->site) {
+ vpr_info("dropping site info %s.%s.%d\n", dp->site->filename,
+ dp->site->function, dp->lineno);
+ dp->site = NULL;
+ }
+ }
}
/*
--
2.29.2
next prev parent reply other threads:[~2020-12-25 20:22 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-25 20:19 [RFC PATCH v2 00/19] dynamic debug diet plan Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 01/19] dyndbg: fix use before null check Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 02/19] dyndbg: split struct _ddebug, move display fields to new _ddebug_callsite Jim Cromie
2020-12-31 2:34 ` [dyndbg] e83b4a5011: leaking-addresses.proc.__dyndbg_callsites kernel test robot
2020-12-25 20:19 ` [RFC PATCH v2 03/19] dyndbg: refactor part of ddebug_change to ddebug_match_site Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 04/19] dyndbg: accept null site in ddebug_match_site Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 05/19] dyndbg: hoist ->site out of ddebug_match_site Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 06/19] dyndbg: accept null site in ddebug_change Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 07/19] dyndbg: accept null site in dynamic_emit_prefix Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 08/19] dyndbg: accept null site in ddebug_proc_show Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 09/19] dyndbg: optimize ddebug_emit_prefix Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 10/19] dyndbg: avoid calling dyndbg_emit_prefix when it has no work Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 11/19] dyndbg: refactor ddebug_alter_site out of ddebug_change Jim Cromie
2020-12-25 20:19 ` Jim Cromie [this message]
2020-12-25 20:19 ` [RFC PATCH v2 13/19] dyndbg: verify __dyndbg & __dyndbg_callsite invariant Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 14/19] dyndbg+module: expose ddebug_callsites to modules Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 15/19] dyndbg: add ddebug_site_get/put api with pass-thru impl Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 16/19] dyndbg: ddebug_site_get/put api commentary Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 17/19] dyndbg: rearrange struct ddebug_callsites Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 18/19] dyndbg: add module_index to struct _ddebug Jim Cromie
2020-12-25 20:19 ` [RFC PATCH v2 19/19] dyndbg: try DEFINE_DYNAMIC_DEBUG_TABLE Jim Cromie
2020-12-29 18:56 ` [RFC PATCH v2 00/19] dynamic debug diet plan Joe Perches
2021-01-06 17:50 ` jim.cromie
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