lkml.org 
[lkml]   [2020]   [Mar]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] ftrace: return first found result in lookup_rec()
Date
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.

Fixes: 7e16f581a817 ("ftrace: Separate out functionality from ftrace_location_range()")
Signed-off-by: Artem Savkov <asavkov@redhat.com>
---
kernel/trace/ftrace.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3f7ee102868a..b0f5ee1fd6e4 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1547,8 +1547,10 @@ 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)
+ return rec;
}
- return rec;
+ return NULL;
}

/**
--
2.21.1
\
 
 \ /
  Last update: 2020-03-06 09:12    [W:0.049 / U:0.700 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site