4.9-stable review patch. If anyone has any objections, please let me know.
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From: Matthias Kaehlcke mka@chromium.org
commit a9903f04e0a4ea522d959c2f287cdf0ab029e324 upstream.
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.
Signed-off-by: Matthias Kaehlcke mka@chromium.org Reviewed-by: Nick Desaulniers nick.desaulniers@gmail.com Cc: Douglas Anderson dianders@chromium.org Cc: Guenter Roeck groeck@chromium.org Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Shile Zhang shile.zhang@nokia.com Cc: Thomas Gleixner tglx@linutronix.de Link: http://lkml.kernel.org/r/20171030180816.170850-1-mka@chromium.org Signed-off-by: Ingo Molnar mingo@kernel.org [nc: Backport to 4.9] Signed-off-by: Nathan Chancellor natechancellor@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/sched/sysctl.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/include/linux/sched/sysctl.h +++ b/include/linux/sched/sysctl.h @@ -33,9 +33,9 @@ extern unsigned int sysctl_numa_balancin extern unsigned int sysctl_numa_balancing_scan_size;
#ifdef CONFIG_SCHED_DEBUG -extern unsigned int sysctl_sched_migration_cost; -extern unsigned int sysctl_sched_nr_migrate; -extern unsigned int sysctl_sched_time_avg; +extern __read_mostly unsigned int sysctl_sched_migration_cost; +extern __read_mostly unsigned int sysctl_sched_nr_migrate; +extern __read_mostly unsigned int sysctl_sched_time_avg; extern unsigned int sysctl_sched_shares_window;
int sched_proc_update_handler(struct ctl_table *table, int write,