On Fri, May 23, 2025 at 12:19:24PM +0200, Clément Léger wrote:
schedule_on_each_cpu() was used without any good reason while documented as very slow. This call was in the boot path, so better use on_each_cpu() for scalar misaligned checking. Vector misaligned check still needs to use schedule_on_each_cpu() since it requires irqs to be enabled but that's less of a problem since this code is ran in a kthread. Add a comment to explicit that.
Signed-off-by: Clément Léger cleger@rivosinc.com Reviewed-by: Andrew Jones ajones@ventanamicro.com
Reviewed-by: Charlie Jenkins charlie@rivosinc.com Tested-by: Charlie Jenkins charlie@rivosinc.com
arch/riscv/kernel/traps_misaligned.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c index 592b1a28e897..34b4a4e9dfca 100644 --- a/arch/riscv/kernel/traps_misaligned.c +++ b/arch/riscv/kernel/traps_misaligned.c @@ -627,6 +627,10 @@ bool __init check_vector_unaligned_access_emulated_all_cpus(void) { int cpu;
- /*
* While being documented as very slow, schedule_on_each_cpu() is used since* kernel_vector_begin() expects irqs to be enabled or it will panic()*/for_each_online_cpu(cpu) @@ -647,7 +651,7 @@ bool __init check_vector_unaligned_access_emulated_all_cpus(void) static bool unaligned_ctl __read_mostly; -static void check_unaligned_access_emulated(struct work_struct *work __always_unused) +static void check_unaligned_access_emulated(void *arg __always_unused) { int cpu = smp_processor_id(); long *mas_ptr = per_cpu_ptr(&misaligned_access_speed, cpu); @@ -688,7 +692,7 @@ bool __init check_unaligned_access_emulated_all_cpus(void) * accesses emulated since tasks requesting such control can run on any * CPU. */
- schedule_on_each_cpu(check_unaligned_access_emulated);
- on_each_cpu(check_unaligned_access_emulated, NULL, 1);
for_each_online_cpu(cpu) if (per_cpu(misaligned_access_speed, cpu) -- 2.49.0