[Skiboot] [PATCH] core/cpu: fix next_ungarded_primary

[Nicholas Piggin]

next_unguarded_primary dereferences NULL CPU -> UB -> infinite loop

Fast reboot works again after this patch.

Fixes: 98f5834253c7e ("cpu: Keep track of the "ec_primary" in big core more")
Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 core/cpu.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/core/cpu.c b/core/cpu.c
index ff0442a8a..d30bef8e0 100644
--- a/core/cpu.c
+++ b/core/cpu.c
@@ -823,11 +823,9 @@ struct cpu_thread *first_ungarded_cpu(void)
 
 struct cpu_thread *next_ungarded_primary(struct cpu_thread *cpu)
 {
-	bool is_primary;
 	do {
-		cpu = next_cpu(cpu);
-		is_primary = cpu == cpu->primary || cpu == cpu->ec_primary;
-	} while(cpu && (cpu->state == cpu_state_unavailable || !is_primary));
+		cpu = next_ungarded_cpu(cpu);
+	} while (cpu && !(cpu == cpu->primary || cpu == cpu->ec_primary));
 
 	return cpu;
 }
-- 
2.23.0