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    Subject[PATCH tip/core/rcu 18/18] rcu/nocb: Suppress uninitialized false-positive in nocb_gp_wait()
    Date
    Some compilers complain that wait_gp_seq might be used uninitialized
    in nocb_gp_wait(). This cannot actually happen because when wait_gp_seq
    is uninitialized, needwait_gp must be false, which prevents wait_gp_seq
    from being used. But this analysis is apparently beyond some compilers,
    so this commit adds a bogus initialization of wait_gp_seq for the sole
    purpose of suppressing the false-positive warning.

    Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
    ---
    kernel/rcu/tree_plugin.h | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
    index 1847fffdfa0a..c1dfbac8cd39 100644
    --- a/kernel/rcu/tree_plugin.h
    +++ b/kernel/rcu/tree_plugin.h
    @@ -1668,12 +1668,12 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
    unsigned long cur_gp_seq;
    unsigned long flags;
    bool gotcbs;
    - bool needwait_gp = false;
    + bool needwait_gp = false; // This prevents actual uninitialized use.
    bool needwake;
    bool needwake_gp;
    struct rcu_data *rdp;
    struct rcu_node *rnp;
    - unsigned long wait_gp_seq;
    + unsigned long wait_gp_seq = 0; // Suppress "use uninitialized" warning.

    /*
    * Each pass through the following loop checks for CBs and for the
    --
    2.17.1
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