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    Subject[PATCH v4 11/39] dyndbg: don't close trace instance when in use
    Date
    Don't allow trace instance to be closed when it
    is still being used by at least one callsite.

    Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
    ---
    lib/dynamic_debug.c | 35 +++++++++++++++++++++++++++++++++++
    1 file changed, 35 insertions(+)

    diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
    index d0d1057911e8..6668f265f2c3 100644
    --- a/lib/dynamic_debug.c
    +++ b/lib/dynamic_debug.c
    @@ -81,6 +81,7 @@ struct flag_settings {
    struct dd_private_tracebuf {
    const char *name;
    struct trace_array *arr;
    + int use_cnt;
    };

    /*
    @@ -279,6 +280,7 @@ static int handle_trace_open_cmd(const char *arg)
    goto end;
    }

    + buf->use_cnt = 0;
    set_bit(idx, trc_tbl.bmap);
    v3pr_info("opened trace instance idx=%d, name=%s\n", idx, arg);
    end:
    @@ -301,6 +303,14 @@ static int handle_trace_close_cmd(const char *arg)

    buf = &trc_tbl.buf[idx];

    + WARN_ON(buf->use_cnt < 0);
    + if (buf->use_cnt) {
    + pr_err("trace instance is being used name=%s, use_cnt=%d\n",
    + buf->name, buf->use_cnt);
    + ret = -EBUSY;
    + goto end;
    + }
    +
    trace_array_put(buf->arr);
    /*
    * don't destroy trace instance but let user do it manually
    @@ -321,6 +331,22 @@ static int handle_trace_close_cmd(const char *arg)
    return ret;
    }

    +static
    +void update_tr_dst(const struct _ddebug *desc, const struct dd_ctrl *nctrl)
    +{
    + int odst = get_trace_dst(desc);
    + int ndst = nctrl->trace_dst;
    +
    + if (odst == ndst)
    + return;
    +
    + if (odst)
    + trc_tbl.buf[odst].use_cnt--;
    +
    + if (ndst)
    + trc_tbl.buf[ndst].use_cnt++;
    +}
    +
    static int ddebug_parse_cmd(char *words[], int nwords)
    {
    if (nwords != 1)
    @@ -447,6 +473,7 @@ static int ddebug_change(const struct ddebug_query *query,
    dt->mod_name, dp->function,
    ddebug_describe_flags(get_flags(dp), &fbuf),
    ddebug_describe_flags(nctrl.flags, &nbuf));
    + update_tr_dst(dp, &nctrl);
    set_ctrl(dp, &nctrl);
    }
    }
    @@ -1628,6 +1655,14 @@ int ddebug_dyndbg_module_param_cb(char *param, char *val, const char *module)

    static void ddebug_table_free(struct ddebug_table *dt)
    {
    + int dst, i;
    +
    + for (i = 0; i < dt->num_ddebugs; i++) {
    + dst = get_trace_dst(&dt->ddebugs[i]);
    + if (dst)
    + trc_tbl.buf[dst].use_cnt--;
    + }
    +
    list_del_init(&dt->link);
    kfree(dt);
    }
    --
    2.43.0.687.g38aa6559b0-goog

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