* Re: [patch -next] rcu: off by one in gp_state_getname()
2015-11-19 19:34 [patch -next] rcu: off by one in gp_state_getname() Dan Carpenter
@ 2015-11-19 21:18 ` Paul E. McKenney
2015-11-20 10:30 ` Dan Carpenter
0 siblings, 1 reply; 4+ messages in thread
From: Paul E. McKenney @ 2015-11-19 21:18 UTC (permalink / raw)
To: Dan Carpenter
Cc: Josh Triplett, Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan,
linux-kernel, kernel-janitors
On Thu, Nov 19, 2015 at 10:34:09PM +0300, Dan Carpenter wrote:
> It should be >= ARRAY_SIZE() instead of > ARRAY_SIZE().
>
> Fixes: 6231da675578 ('rcu: Print symbolic name for ->gp_state')
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Good catch! I folded this into the original commit with attribution,
please see below.
Thanx, Paul
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 6a5e1c4..6559b3c 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -1203,7 +1203,7 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
> */
> static char *gp_state_getname(short gs)
> {
> - if (gs < 0 || gs > ARRAY_SIZE(gp_state_names))
> + if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
> return "???";
> return gp_state_names[gs];
> }
------------------------------------------------------------------------
commit 31bf937d2dcbe71a329e5bc6c7726f3a5949089a
Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Tue Nov 17 14:39:26 2015 -0800
rcu: Print symbolic name for ->gp_state
Currently, ->gp_state is printed as an integer, which slows debugging.
This commit therefore prints a symbolic name in addition to the integer.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ Updated to fix relational operator called out by Daniel Carpenter. ]
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index e768fc64583f..6559b3cb5ea6 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1199,6 +1199,16 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
}
/*
+ * Convert a ->gp_state value to a character string.
+ */
+static char *gp_state_getname(short gs)
+{
+ if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
+ return "???";
+ return gp_state_names[gs];
+}
+
+/*
* Complain about starvation of grace-period kthread.
*/
static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
@@ -1209,10 +1219,11 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp)
j = jiffies;
gpa = READ_ONCE(rsp->gp_activity);
if (j - gpa > 2 * HZ) {
- pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x s%d ->state=%#lx\n",
+ pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x %s(%d) ->state=%#lx\n",
rsp->name, j - gpa,
rsp->gpnum, rsp->completed,
- rsp->gp_flags, rsp->gp_state,
+ rsp->gp_flags,
+ gp_state_getname(rsp->gp_state), rsp->gp_state,
rsp->gp_kthread ? rsp->gp_kthread->state : ~0);
if (rsp->gp_kthread)
sched_show_task(rsp->gp_kthread);
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 6cbec31f99d6..5c70b09a85d4 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -546,6 +546,15 @@ struct rcu_state {
#define RCU_GP_DOING_FQS 4 /* Wait done for force-quiescent-state time. */
#define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */
#define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */
+static char * const gp_state_names[] = {
+ "RCU_GP_IDLE",
+ "RCU_GP_WAIT_GPS",
+ "RCU_GP_DONE_GPS",
+ "RCU_GP_WAIT_FQS",
+ "RCU_GP_DOING_FQS",
+ "RCU_GP_CLEANUP",
+ "RCU_GP_CLEANED",
+};
extern struct list_head rcu_struct_flavors;
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