Commit 21d0d79a authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Inline RCU task stall-warning helper functions 



The rcu_print_detail_task_stall(), rcu_print_task_stall_begin(), and
rcu_print_task_stall_end() functions were defined to allow long-gone
Kconfig options to provide an abbreviated RCU CPU stall warning printout.
This commit saves a few lines of code by inlining them into their sole
callers.

While in the area, a useless call of rcu_print_detail_task_stall_rnp()
on the root rcu_node structure was eliminated.  If there is only one
rcu_node structure, its tasks get printed twice, but if there are more,
the root rcu_node structure is guaranteed to have an empty list of blocked
tasks, hence the uselessness.  (Long ago, root rcu_node structures with
non-empty ->blkd_tasks lists could happen, but no longer.)

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.ibm.com>
parent 32255d51

kernel/rcu/tree.h

+0 −1
Original line number Diff line number Diff line
@@ -445,7 +445,6 @@ static void rcu_dynticks_task_enter(void); 
static void rcu_dynticks_task_exit(void);



/* Forward declarations for tree_stall.h */

static void rcu_print_detail_task_stall(void);

static int rcu_print_task_stall(struct rcu_node *rnp);

static void record_gp_stall_check_time(void);

static void check_cpu_stall(struct rcu_data *rdp);

kernel/rcu/tree_stall.h

+7 −29
Original line number Diff line number Diff line
@@ -94,30 +94,6 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp) 
	raw_spin_unlock_irqrestore_rcu_node(rnp, flags);

}



/*

 * Dump detailed information for all tasks blocking the current RCU

 * grace period.

 */

static void rcu_print_detail_task_stall(void)

{

	struct rcu_node *rnp = rcu_get_root();



	rcu_print_detail_task_stall_rnp(rnp);

	rcu_for_each_leaf_node(rnp)

		rcu_print_detail_task_stall_rnp(rnp);

}



static void rcu_print_task_stall_begin(struct rcu_node *rnp)

{

	pr_err("\tTasks blocked on level-%d rcu_node (CPUs %d-%d):",

	       rnp->level, rnp->grplo, rnp->grphi);

}



static void rcu_print_task_stall_end(void)

{

	pr_cont("\n");

}



/*

 * Scan the current list of tasks blocked within RCU read-side critical

 * sections, printing out the tid of each.
@@ -129,14 +105,15 @@ static int rcu_print_task_stall(struct rcu_node *rnp) 


	if (!rcu_preempt_blocked_readers_cgp(rnp))

		return 0;

	rcu_print_task_stall_begin(rnp);

	pr_err("\tTasks blocked on level-%d rcu_node (CPUs %d-%d):",

	       rnp->level, rnp->grplo, rnp->grphi);

	t = list_entry(rnp->gp_tasks->prev,

		       struct task_struct, rcu_node_entry);

	list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry) {

		pr_cont(" P%d", t->pid);

		ndetected++;

	}

	rcu_print_task_stall_end();

	pr_cont("\n");

	return ndetected;

}
@@ -146,7 +123,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp) 
 * Because preemptible RCU does not exist, we never have to check for

 * tasks blocked within RCU read-side critical sections.

 */

static void rcu_print_detail_task_stall(void)

static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp)

{

}
@@ -253,7 +230,7 @@ static void print_other_cpu_stall(unsigned long gp_seq) 
	unsigned long gpa;

	unsigned long j;

	int ndetected = 0;

	struct rcu_node *rnp = rcu_get_root();

	struct rcu_node *rnp;

	long totqlen = 0;



	/* Kick and suppress, if so configured. */
@@ -291,7 +268,8 @@ static void print_other_cpu_stall(unsigned long gp_seq) 
		rcu_dump_cpu_stacks();



		/* Complain about tasks blocking the grace period. */

		rcu_print_detail_task_stall();

		rcu_for_each_leaf_node(rnp)

			rcu_print_detail_task_stall_rnp(rnp);

	} else {

		if (rcu_seq_current(&rcu_state.gp_seq) != gp_seq) {

			pr_err("INFO: Stall ended before state dump start\n");

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