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    Subject[PATCH v2 4/7] blktrace: fix memory leak when freeing struct blk_io_trace
    When mixing the use of ioctl-based blktrace and ftrace-based blktrace,
    we can leak memory in this way:
    # btrace /dev/sda > /dev/null &
    # echo 0 > /sys/block/sda/sda1/trace/enable
    now we leak bt->dropped_file, bt->msg_file, bt->rchan...

    Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
    ---
    kernel/trace/blktrace.c | 29 ++++++++++++-----------------
    1 files changed, 12 insertions(+), 17 deletions(-)

    diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
    index 8d6bd12..2f21d77 100644
    --- a/kernel/trace/blktrace.c
    +++ b/kernel/trace/blktrace.c
    @@ -247,7 +247,7 @@ record_it:
    static struct dentry *blk_tree_root;
    static DEFINE_MUTEX(blk_tree_mutex);

    -static void blk_trace_cleanup(struct blk_trace *bt)
    +static void blk_trace_free(struct blk_trace *bt)
    {
    debugfs_remove(bt->msg_file);
    debugfs_remove(bt->dropped_file);
    @@ -255,6 +255,11 @@ static void blk_trace_cleanup(struct blk_trace *bt)
    free_percpu(bt->sequence);
    free_percpu(bt->msg_data);
    kfree(bt);
    +}
    +
    +static void blk_trace_cleanup(struct blk_trace *bt)
    +{
    + blk_trace_free(bt);
    if (atomic_dec_and_test(&blk_probes_ref))
    blk_unregister_tracepoints();
    }
    @@ -410,11 +415,11 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
    if (buts->name[i] == '/')
    buts->name[i] = '_';

    - ret = -ENOMEM;
    bt = kzalloc(sizeof(*bt), GFP_KERNEL);
    if (!bt)
    - goto err;
    + return -ENOMEM;

    + ret = -ENOMEM;
    bt->sequence = alloc_percpu(unsigned long);
    if (!bt->sequence)
    goto err;
    @@ -483,17 +488,7 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,

    return 0;
    err:
    - if (bt) {
    - if (bt->msg_file)
    - debugfs_remove(bt->msg_file);
    - if (bt->dropped_file)
    - debugfs_remove(bt->dropped_file);
    - free_percpu(bt->sequence);
    - free_percpu(bt->msg_data);
    - if (bt->rchan)
    - relay_close(bt->rchan);
    - kfree(bt);
    - }
    + blk_trace_free(bt);
    return ret;
    }

    @@ -1091,6 +1086,7 @@ static void blk_tracer_print_header(struct seq_file *m)

    static void blk_tracer_start(struct trace_array *tr)
    {
    + blk_tracer_enabled = true;
    trace_flags &= ~TRACE_ITER_CONTEXT_INFO;
    }

    @@ -1098,18 +1094,17 @@ static int blk_tracer_init(struct trace_array *tr)
    {
    blk_tr = tr;
    blk_tracer_start(tr);
    - blk_tracer_enabled = true;
    return 0;
    }

    static void blk_tracer_stop(struct trace_array *tr)
    {
    + blk_tracer_enabled = false;
    trace_flags |= TRACE_ITER_CONTEXT_INFO;
    }

    static void blk_tracer_reset(struct trace_array *tr)
    {
    - blk_tracer_enabled = false;
    blk_tracer_stop(tr);
    }

    @@ -1250,7 +1245,7 @@ static int blk_trace_remove_queue(struct request_queue *q)
    if (atomic_dec_and_test(&blk_probes_ref))
    blk_unregister_tracepoints();

    - kfree(bt);
    + blk_trace_free(bt);
    return 0;
    }

    --
    1.5.4.rc3




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