From: Artem Savkov <asavkov@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, live-patching@vger.kernel.org,
Artem Savkov <asavkov@redhat.com>
Subject: [PATCH v2] ftrace: return first found result in lookup_rec()
Date: Fri, 6 Mar 2020 18:43:17 +0100 [thread overview]
Message-ID: <20200306174317.21699-1-asavkov@redhat.com> (raw)
In-Reply-To: <20200306121246.5dac2573@gandalf.local.home>
It appears that ip ranges can overlap so. In that case lookup_rec()
returns whatever results it got last even if it found nothing in last
searched page.
This breaks an obscure livepatch late module patching usecase:
- load livepatch
- load the patched module
- unload livepatch
- try to load livepatch again
To fix this return from lookup_rec() as soon as it found the record
containing searched-for ip. This used to be this way prior lookup_rec()
introduction.
v2: break instead of two returns
Fixes: 7e16f581a817 ("ftrace: Separate out functionality from ftrace_location_range()")
Signed-off-by: Artem Savkov <asavkov@redhat.com>
---
kernel/trace/ftrace.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3f7ee102868a..fd81c7de77a7 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1547,6 +1547,8 @@ static struct dyn_ftrace *lookup_rec(unsigned long start, unsigned long end)
rec = bsearch(&key, pg->records, pg->index,
sizeof(struct dyn_ftrace),
ftrace_cmp_recs);
+ if (rec)
+ break;
}
return rec;
}
--
2.21.1
next prev parent reply other threads:[~2020-03-06 17:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-06 8:10 [PATCH] ftrace: return first found result in lookup_rec() Artem Savkov
2020-03-06 17:12 ` Steven Rostedt
2020-03-06 17:43 ` Artem Savkov [this message]
2020-03-10 19:38 ` [PATCH v2] " Steven Rostedt
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