rcu: Suppress levelspread uninitialized messages

paulmckrcu · paulmckrcu · commit 36b5dae64513 · 2019-10-30T08:34:53.000-07:00
New tools bring new warnings, and with v5.3 comes:

kernel/rcu/srcutree.c: warning: 'levelspread[&lt;U aa0&gt;]' may be used uninitialized in this function [-Wuninitialized]:  =&gt; 121:34

This commit suppresses this warning by initializing the full array
to INT_MIN, which will result in failures should any out-of-bounds
references appear.

Reported-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Reported-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
Reviewed-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
@@ -299,6 +299,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
 {
 	int i;
 
+	for (i = 0; i < RCU_NUM_LVLS; i++)
+		levelspread[i] = INT_MIN;
 	if (rcu_fanout_exact) {
 		levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
 		for (i = rcu_num_lvls - 2; i >= 0; i--)

Original file line number	Diff line number	Diff line change
`@@ -299,6 +299,8 @@ static inline void rcu_init_levelspread(int levelspread, const int levelcnt)`
`299`	`299`	`{`
`300`	`300`	`int i;`
`301`	`301`
	`302`	`+ for (i = 0; i < RCU_NUM_LVLS; i++)`
	`303`	`+ levelspread[i] = INT_MIN;`
`302`	`304`	`if (rcu_fanout_exact) {`
`303`	`305`	`levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;`
`304`	`306`	`for (i = rcu_num_lvls - 2; i >= 0; i--)`