--- zzzz-none-000/linux-3.10.107/Documentation/local_ops.txt 2017-06-27 09:49:32.000000000 +0000 +++ scorpion-7490-727/linux-3.10.107/Documentation/local_ops.txt 2021-02-04 17:41:59.000000000 +0000 @@ -8,6 +8,11 @@ properly. It also stresses on the precautions that must be taken when reading those local variables across CPUs when the order of memory writes matters. +Note that local_t based operations are not recommended for general kernel use. +Please use the this_cpu operations instead unless there is really a special purpose. +Most uses of local_t in the kernel have been replaced by this_cpu operations. +this_cpu operations combine the relocation with the local_t like semantics in +a single instruction and yield more compact and faster executing code. * Purpose of local atomic operations @@ -87,10 +92,10 @@ local_inc(&get_cpu_var(counters)); put_cpu_var(counters); -If you are already in a preemption-safe context, you can directly use -__get_cpu_var() instead. +If you are already in a preemption-safe context, you can use +this_cpu_ptr() instead. - local_inc(&__get_cpu_var(counters)); + local_inc(this_cpu_ptr(&counters)); @@ -134,7 +139,7 @@ { /* Increment the counter from a non preemptible context */ printk("Increment on cpu %d\n", smp_processor_id()); - local_inc(&__get_cpu_var(counters)); + local_inc(this_cpu_ptr(&counters)); /* This is what incrementing the variable would look like within a * preemptible context (it disables preemption) :