drivers: base: cacheinfo: Ensure cpu hotplug work is done before Intel RDT

The cacheinfo structures are alloced/freed by cpu online/offline
callbacks. Originally these were only used by sysfs to expose the
cache topology to user space. Without any in-kernel dependencies
CPUHP_AP_ONLINE_DYN was an appropriate choice.

resctrl has started using these structures to identify CPUs that
share a cache. It updates its 'domain' structures from cpu
online/offline callbacks. These depend on the cacheinfo structures
(resctrl_online_cpu()->domain_add_cpu()->get_cache_id()->
 get_cpu_cacheinfo()).
These also run as CPUHP_AP_ONLINE_DYN.

Now that there is an in-kernel dependency, move the cacheinfo
work earlier so we know its done before resctrl's CPUHP_AP_ONLINE_DYN
work runs.

Fixes: 2264d9c74dda1 ("x86/intel_rdt: Build structures for each resource based on cache topology")
Cc: <stable@vger.kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: James Morse <james.morse@arm.com>
Link: https://lore.kernel.org/r/20190624173656.202407-1-james.morse@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index a735953..b444f89 100644 (file)
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -655,7 +655,8 @@ static int cacheinfo_cpu_pre_down(unsigned int cpu)
 
 static int __init cacheinfo_sysfs_init(void)
 {
-       return cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "base/cacheinfo:online",
+       return cpuhp_setup_state(CPUHP_AP_BASE_CACHEINFO_ONLINE,
+                                "base/cacheinfo:online",
                                 cacheinfo_cpu_online, cacheinfo_cpu_pre_down);
 }
 device_initcall(cacheinfo_sysfs_init);

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 6a38159..50c893f 100644 (file)
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -175,6 +175,7 @@ enum cpuhp_state {
        CPUHP_AP_WATCHDOG_ONLINE,
        CPUHP_AP_WORKQUEUE_ONLINE,
        CPUHP_AP_RCUTREE_ONLINE,
+       CPUHP_AP_BASE_CACHEINFO_ONLINE,
        CPUHP_AP_ONLINE_DYN,
        CPUHP_AP_ONLINE_DYN_END         = CPUHP_AP_ONLINE_DYN + 30,
        CPUHP_AP_X86_HPET_ONLINE,