From 4b334484fa7f44baa369db0bbab534f853520f64 Mon Sep 17 00:00:00 2001 From: Jim Cromie Date: Sun, 19 Jul 2020 17:10:56 -0600 Subject: [PATCH] dyndbg: allow anchored match on format query term This should work: echo module=amd* format=^[IF_TRACE]: +p >/proc/dynamic_debug/control consider drivers/gpu/drm/amd/display/include/logger_types.h: It has 11 defines like: #define DC_LOG_IF_TRACE(...) pr_debug("[IF_TRACE]:"__VA_ARGS__) These defines are used 804 times at recent count; they are a good use case to evaluate existing format-message based classifications of *pr_debug*. Those macros prefix the supplied format with a fixed string, I'd expect most existing message classification schemes to do something similar. Hence we want to be able to anchor our match to the beginning of the format string, allowing easy construction of clear and precise queries, leveraging the existing classification scheme to enable and disable those callsites. Note that unlike other search terms, formats are implicitly floating substring matches, without the need for explicit wildcards. This makes no attempt at wider regex features, just the one we need. TLDR: Using the anchor also means the []s are less helpful for disamiguating the prefix from a random in-message occurrence, allowing shorter prefixes. Acked-by: Signed-off-by: Jim Cromie Link: https://lore.kernel.org/r/20200719231058.1586423-17-jim.cromie@gmail.com Signed-off-by: Greg Kroah-Hartman --- lib/dynamic_debug.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index c983049e986d..c72bb4d2eb7e 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -181,9 +181,16 @@ static int ddebug_change(const struct ddebug_query *query, continue; /* match against the format */ - if (query->format && - !strstr(dp->format, query->format)) - continue; + if (query->format) { + if (*query->format == '^') { + char *p; + /* anchored search. match must be at beginning */ + p = strstr(dp->format, query->format+1); + if (p != dp->format) + continue; + } else if (!strstr(dp->format, query->format)) + continue; + } /* match against the line number range */ if (query->first_lineno &&