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From: Andy Isaacson on 15 Jul 2010 13:30
blktrace fails to completely clean up after itself if BLKTRACESTOP is
called before the final trace file is closed:

% blktrace /dev/sdb &
% exec 6</sys/kernel/debug/block/sdb/trace0
% kill %1
% find /sys/kernel/debug/block/
/sys/kernel/debug/block/
/sys/kernel/debug/block/sdb
/sys/kernel/debug/block/sdb/trace0
% exec 6<&-
% find /sys/kernel/debug/block/
/sys/kernel/debug/block/
/sys/kernel/debug/block/sdb

The proper fix is to move cleanup from BLKTRACESTOP to the close
routine, but that's nontrivial, so here's a simple fix to remove
debug/block/<dev> when the last trace%d file is closed.

Cc: stable(a)kernel.org
Signed-off-by: Andy Isaacson <adi(a)hexapodia.org>
---
kernel/trace/blktrace.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 347fe8e..9b78930 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -383,8 +383,12 @@ static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,

static int blk_remove_buf_file_callback(struct dentry *dentry)
{
+ struct dentry *parent = dentry->d_parent;
debugfs_remove(dentry);

+ if (simple_empty(parent))
+ debugfs_remove(parent);
+
return 0;
}

--
1.7.1
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Prev: [PATCH 1/2] blktrace: use cmpxchg
Next: kmemleak: Add support for NO_BOOTMEM configurations