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-rw-r--r--drivers/acpi/processor_driver.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index bd4e5dc..a4352b8 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -852,8 +852,22 @@ static int acpi_processor_handle_eject(struct acpi_processor *pr)
if (cpu_online(pr->id))
cpu_down(pr->id);
+ get_online_cpus();
+ /*
+ * The cpu might become online again at this point. So we check whether
+ * the cpu has been onlined or not. If the cpu became online, it means
+ * that someone wants to use the cpu. So acpi_processor_handle_eject()
+ * returns -EAGAIN.
+ */
+ if (unlikely(cpu_online(pr->id))) {
+ put_online_cpus();
+ pr_warn("Failed to remove CPU %d, because other task "
+ "brought the CPU back online\n", pr->id);
+ return -EAGAIN;
+ }
arch_unregister_cpu(pr->id);
acpi_unmap_lsapic(pr->id);
+ put_online_cpus();
return (0);
}
#else