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rcu: Extract synchronize_rcu_expedited_stall() from synchronize_rcu_expedited_wait()

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This commit extracts the RCU CPU stall-warning report code from
synchronize_rcu_expedited_wait() and places it in a new function named
synchronize_rcu_expedited_stall().  This is strictly a code-movement
commit.  A later commit will use this reorganization to avoid printing
expedited RCU CPU stall warnings while there are ongoing CSD-lock stall
reports.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
This commit is contained in:
Paul E. McKenney 2024-07-01 21:19:06 -07:00 committed by Neeraj Upadhyay
parent 1dd01c0650
commit 27d5749d07
1 changed files with 60 additions and 51 deletions
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111
kernel/rcu/tree_exp.h
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@ -542,6 +542,65 @@ static bool synchronize_rcu_expedited_wait_once(long tlimit)
return false;
}
/*
* Print out an expedited RCU CPU stall warning message.
*/
static void synchronize_rcu_expedited_stall(unsigned long jiffies_start, unsigned long j)
{
int cpu;
unsigned long mask;
int ndetected;
struct rcu_node *rnp;
struct rcu_node *rnp_root = rcu_get_root();
pr_err("INFO: %s detected expedited stalls on CPUs/tasks: {", rcu_state.name);
ndetected = 0;
rcu_for_each_leaf_node(rnp) {
ndetected += rcu_print_task_exp_stall(rnp);
for_each_leaf_node_possible_cpu(rnp, cpu) {
struct rcu_data *rdp;
mask = leaf_node_cpu_bit(rnp, cpu);
if (!(READ_ONCE(rnp->expmask) & mask))
continue;
ndetected++;
rdp = per_cpu_ptr(&rcu_data, cpu);
pr_cont(" %d-%c%c%c%c", cpu,
"O."[!!cpu_online(cpu)],
"o."[!!(rdp->grpmask & rnp->expmaskinit)],
"N."[!!(rdp->grpmask & rnp->expmaskinitnext)],
"D."[!!data_race(rdp->cpu_no_qs.b.exp)]);
}
}
pr_cont(" } %lu jiffies s: %lu root: %#lx/%c\n",
j - jiffies_start, rcu_state.expedited_sequence, data_race(rnp_root->expmask),
".T"[!!data_race(rnp_root->exp_tasks)]);
if (ndetected) {
pr_err("blocking rcu_node structures (internal RCU debug):");
rcu_for_each_node_breadth_first(rnp) {
if (rnp == rnp_root)
continue; /* printed unconditionally */
if (sync_rcu_exp_done_unlocked(rnp))
continue;
pr_cont(" l=%u:%d-%d:%#lx/%c",
rnp->level, rnp->grplo, rnp->grphi, data_race(rnp->expmask),
".T"[!!data_race(rnp->exp_tasks)]);
}
pr_cont("\n");
}
rcu_for_each_leaf_node(rnp) {
for_each_leaf_node_possible_cpu(rnp, cpu) {
mask = leaf_node_cpu_bit(rnp, cpu);
if (!(READ_ONCE(rnp->expmask) & mask))
continue;
preempt_disable(); // For smp_processor_id() in dump_cpu_task().
dump_cpu_task(cpu);
preempt_enable();
}
rcu_exp_print_detail_task_stall_rnp(rnp);
}
}
/*
* Wait for the expedited grace period to elapse, issuing any needed
* RCU CPU stall warnings along the way.
@ -553,10 +612,8 @@ static void synchronize_rcu_expedited_wait(void)
unsigned long jiffies_stall;
unsigned long jiffies_start;
unsigned long mask;
int ndetected;
struct rcu_data *rdp;
struct rcu_node *rnp;
struct rcu_node *rnp_root = rcu_get_root();
unsigned long flags;
trace_rcu_exp_grace_period(rcu_state.name, rcu_exp_gp_seq_endval(), TPS("startwait"));
@ -593,55 +650,7 @@ static void synchronize_rcu_expedited_wait(void)
j = jiffies;
rcu_stall_notifier_call_chain(RCU_STALL_NOTIFY_EXP, (void *)(j - jiffies_start));
trace_rcu_stall_warning(rcu_state.name, TPS("ExpeditedStall"));
pr_err("INFO: %s detected expedited stalls on CPUs/tasks: {",
rcu_state.name);
ndetected = 0;
rcu_for_each_leaf_node(rnp) {
ndetected += rcu_print_task_exp_stall(rnp);
for_each_leaf_node_possible_cpu(rnp, cpu) {
struct rcu_data *rdp;
mask = leaf_node_cpu_bit(rnp, cpu);
if (!(READ_ONCE(rnp->expmask) & mask))
continue;
ndetected++;
rdp = per_cpu_ptr(&rcu_data, cpu);
pr_cont(" %d-%c%c%c%c", cpu,
"O."[!!cpu_online(cpu)],
"o."[!!(rdp->grpmask & rnp->expmaskinit)],
"N."[!!(rdp->grpmask & rnp->expmaskinitnext)],
"D."[!!data_race(rdp->cpu_no_qs.b.exp)]);
}
}
pr_cont(" } %lu jiffies s: %lu root: %#lx/%c\n",
j - jiffies_start, rcu_state.expedited_sequence,
data_race(rnp_root->expmask),
".T"[!!data_race(rnp_root->exp_tasks)]);
if (ndetected) {
pr_err("blocking rcu_node structures (internal RCU debug):");
rcu_for_each_node_breadth_first(rnp) {
if (rnp == rnp_root)
continue; /* printed unconditionally */
if (sync_rcu_exp_done_unlocked(rnp))
continue;
pr_cont(" l=%u:%d-%d:%#lx/%c",
rnp->level, rnp->grplo, rnp->grphi,
data_race(rnp->expmask),
".T"[!!data_race(rnp->exp_tasks)]);
}
pr_cont("\n");
}
rcu_for_each_leaf_node(rnp) {
for_each_leaf_node_possible_cpu(rnp, cpu) {
mask = leaf_node_cpu_bit(rnp, cpu);
if (!(READ_ONCE(rnp->expmask) & mask))
continue;
preempt_disable(); // For smp_processor_id() in dump_cpu_task().
dump_cpu_task(cpu);
preempt_enable();
}
rcu_exp_print_detail_task_stall_rnp(rnp);
}
synchronize_rcu_expedited_stall(jiffies_start, j);
jiffies_stall = 3 * rcu_exp_jiffies_till_stall_check() + 3;
panic_on_rcu_stall();
}