rcu/nocb: Suppress uninitialized false-positive in nocb_gp_wait()

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>

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 1847fff..c1dfbac 100644 (file)
--- 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