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Subject[PATCH tip/core/rcu 04/18] torture: Forgive -EBUSY from boottime CPU-hotplug operations
Date
From: "Paul E. McKenney" <paulmck@kernel.org>

During boot, CPU hotplug is often disabled, for example by PCI probing.
On large systems that take substantial time to boot, this can result
in spurious RCU_HOTPLUG errors. This commit therefore forgives any
boottime -EBUSY CPU-hotplug failures by adjusting counters to pretend
that the corresponding attempt never happened. A non-splat record
of the failed attempt is emitted to the console with the added string
"(-EBUSY forgiven during boot)".

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/torture.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/kernel/torture.c b/kernel/torture.c
index 7c13f55..e377b5b 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -84,6 +84,7 @@ bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
{
unsigned long delta;
int ret;
+ char *s;
unsigned long starttime;

if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
@@ -99,10 +100,16 @@ bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
(*n_offl_attempts)++;
ret = cpu_down(cpu);
if (ret) {
+ s = "";
+ if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
+ // PCI probe frequently disables hotplug during boot.
+ (*n_offl_attempts)--;
+ s = " (-EBUSY forgiven during boot)";
+ }
if (verbose)
pr_alert("%s" TORTURE_FLAG
- "torture_onoff task: offline %d failed: errno %d\n",
- torture_type, cpu, ret);
+ "torture_onoff task: offline %d failed%s: errno %d\n",
+ torture_type, cpu, s, ret);
} else {
if (verbose > 1)
pr_alert("%s" TORTURE_FLAG
@@ -137,6 +144,7 @@ bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
{
unsigned long delta;
int ret;
+ char *s;
unsigned long starttime;

if (cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
@@ -150,10 +158,16 @@ bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
(*n_onl_attempts)++;
ret = cpu_up(cpu);
if (ret) {
+ s = "";
+ if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
+ // PCI probe frequently disables hotplug during boot.
+ (*n_onl_attempts)--;
+ s = " (-EBUSY forgiven during boot)";
+ }
if (verbose)
pr_alert("%s" TORTURE_FLAG
- "torture_onoff task: online %d failed: errno %d\n",
- torture_type, cpu, ret);
+ "torture_onoff task: online %d failed%s: errno %d\n",
+ torture_type, cpu, s, ret);
} else {
if (verbose > 1)
pr_alert("%s" TORTURE_FLAG
--
2.9.5
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