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 <[email protected]> > Reviewed-by: Andrew Jones <[email protected]>
Reviewed-by: Charlie Jenkins <[email protected]> Tested-by: Charlie Jenkins <[email protected]> > --- > 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() > + */ > schedule_on_each_cpu(check_vector_unaligned_access_emulated); > > 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 >
