On 13/03/2025 13:57, Andrew Jones wrote: > On Mon, Mar 10, 2025 at 04:12:12PM +0100, 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@xxxxxxxxxxxx> >> --- >> arch/riscv/kernel/traps_misaligned.c | 9 +++++++-- >> 1 file changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c >> index 90ac74191357..ffac424faa88 100644 >> --- a/arch/riscv/kernel/traps_misaligned.c >> +++ b/arch/riscv/kernel/traps_misaligned.c >> @@ -616,6 +616,11 @@ bool check_vector_unaligned_access_emulated_all_cpus(void) >> return false; >> } >> >> + /* >> + * 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(). > > which expects Hum that would yield the following: "schedule_on_each_cpu() is used since kernel_vector_begin() that is called inside the vector code 'which' expects irqs to be enabled or it will panic()." which seems wrong as well. I guess something like this would be better: "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()" Thanks, Clément > >> + */ >> schedule_on_each_cpu(check_vector_unaligned_access_emulated); >> >> for_each_online_cpu(cpu) >> @@ -636,7 +641,7 @@ bool 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); >> @@ -677,7 +682,7 @@ bool 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) >> -- >> 2.47.2 >> > > Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>