The definition of sysctl_sched_migration_cost, sysctl_sched_nr_migrate and sysctl_sched_time_avg includes the attribute const_debug. This attribute is not part of the extern declaration of these variables in include/linux/sched/sysctl.h, while it is in kernel/sched/sched.h, and as a result Clang generates warnings like this: kernel/sched/sched.h:1618:33: warning: section attribute is specified on redeclared variable [-Wsection] extern const_debug unsigned int sysctl_sched_time_avg; ^ ./include/linux/sched/sysctl.h:42:21: note: previous declaration is here extern unsigned int sysctl_sched_time_avg; The header only declares the variables when CONFIG_SCHED_DEBUG is defined, therefore it is not necessary to duplicate the definition of const_debug. Instead we can use the attribute __read_mostly, which is the expansion of const_debug when CONFIG_SCHED_DEBUG=y is set.
Unified · Split
| @@ -37,9 +37,9 @@ extern unsigned int sysctl_numa_balancing_scan_period_max; · 36 unmodified lines | ||
| 37 | 37 | extern unsigned int sysctl_numa_balancing_scan_size; |
| 38 | 38 | |
| 39 | 39 | #ifdef CONFIG_SCHED_DEBUG |
| 40 | −extern unsigned int sysctl_sched_migration_cost; | |
| 41 | −extern unsigned int sysctl_sched_nr_migrate; | |
| 42 | −extern unsigned int sysctl_sched_time_avg; | |
| 40 | +extern __read_mostly unsigned int sysctl_sched_migration_cost; | |
| 41 | +extern __read_mostly unsigned int sysctl_sched_nr_migrate; | |
| 42 | +extern __read_mostly unsigned int sysctl_sched_time_avg; | |
| 43 | 43 | |
| 44 | 44 | int sched_proc_update_handler(struct ctl_table *table, int write, |
| 45 | 45 | void __user *buffer, size_t *length, |