[PATCH] riscv: Fix fast_unaligned_access_speed_key not getting initialized

From: Nam Cao

Date: Tue Apr 07 2026 - 08:06:58 EST


The static key fast_unaligned_access_speed_key is supposed to be
initialized after check_unaligned_access_all_cpus() has been completed.

However, check_unaligned_access_all_cpus() has been moved to late_initcall
while setting fast_unaligned_access_speed_key still happens at
arch_initcall_sync, thus the static key does not get properly initialized.

fast_unaligned_access_speed_key can still be initialized in CPU hotplug
events, but that cannot be relied on.

Move fast_unaligned_access_speed_key's initialization into
check_unaligned_access_all_cpus() to fix this issue. This also prevent
someone from moving one initcall while forgetting the other in the future.

Fixes: 6455c6c11827 ("riscv: Clean up & optimize unaligned scalar access probe")
Reported-by: Michael Neuling <mikey@xxxxxxxxxxx>
Closes: https://lore.kernel.org/linux-riscv/CAEjGV6y0=bSLp_wrS0uHFj1S2TCRtz4GKzaU5O-L1VV-EL7Nnw@xxxxxxxxxxxxxx/
Signed-off-by: Nam Cao <namcao@xxxxxxxxxxxxx>
---
arch/riscv/kernel/unaligned_access_speed.c | 15 ++++-----------
1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/arch/riscv/kernel/unaligned_access_speed.c b/arch/riscv/kernel/unaligned_access_speed.c
index 485ab1d105d3..11c781a4de73 100644
--- a/arch/riscv/kernel/unaligned_access_speed.c
+++ b/arch/riscv/kernel/unaligned_access_speed.c
@@ -235,17 +235,6 @@ static void set_unaligned_access_static_branches(void)
modify_unaligned_access_branches(&fast_and_online, num_online_cpus());
}

-static int __init lock_and_set_unaligned_access_static_branch(void)
-{
- cpus_read_lock();
- set_unaligned_access_static_branches();
- cpus_read_unlock();
-
- return 0;
-}
-
-arch_initcall_sync(lock_and_set_unaligned_access_static_branch);
-
static int riscv_online_cpu(unsigned int cpu)
{
int ret = cpu_online_unaligned_access_init(cpu);
@@ -440,6 +429,10 @@ static int __init check_unaligned_access_all_cpus(void)
cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "riscv:online",
riscv_online_cpu_vec, NULL);

+ cpus_read_lock();
+ set_unaligned_access_static_branches();
+ cpus_read_unlock();
+
return 0;
}

--
2.47.3