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authorThomas Gleixner <tglx@linutronix.de>2017-01-10 16:01:05 +0300
committerThomas Gleixner <tglx@linutronix.de>2017-01-16 15:20:05 +0300
commit4205e4786d0b9fc3b4fec7b1910cf645a0468307 (patch)
tree685ccb486409197b936c785eb9d173c3edff45a1 /kernel
parent7e164ce4e8ecd7e9a58a83750bd3ee03125df154 (diff)
downloadlinux-4205e4786d0b9fc3b4fec7b1910cf645a0468307.tar.xz
cpu/hotplug: Provide dynamic range for prepare stage
Mathieu reported that the LTTNG modules are broken as of 4.10-rc1 due to the removal of the cpu hotplug notifiers. Usually I don't care much about out of tree modules, but LTTNG is widely used in distros. There are two ways to solve that: 1) Reserve a hotplug state for LTTNG 2) Add a dynamic range for the prepare states. While #1 is the simplest solution, #2 is the proper one as we can convert in tree users, which do not care about ordering, to the dynamic range as well. Add a dynamic range which allows LTTNG to request states in the prepare stage. Reported-and-tested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Sewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701101353010.3401@nanos Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cpu.c22
1 files changed, 18 insertions, 4 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c
index f75c4d031eeb..c47506357519 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1302,10 +1302,24 @@ static int cpuhp_cb_check(enum cpuhp_state state)
*/
static int cpuhp_reserve_state(enum cpuhp_state state)
{
- enum cpuhp_state i;
+ enum cpuhp_state i, end;
+ struct cpuhp_step *step;
- for (i = CPUHP_AP_ONLINE_DYN; i <= CPUHP_AP_ONLINE_DYN_END; i++) {
- if (!cpuhp_ap_states[i].name)
+ switch (state) {
+ case CPUHP_AP_ONLINE_DYN:
+ step = cpuhp_ap_states + CPUHP_AP_ONLINE_DYN;
+ end = CPUHP_AP_ONLINE_DYN_END;
+ break;
+ case CPUHP_BP_PREPARE_DYN:
+ step = cpuhp_bp_states + CPUHP_BP_PREPARE_DYN;
+ end = CPUHP_BP_PREPARE_DYN_END;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ for (i = state; i <= end; i++, step++) {
+ if (!step->name)
return i;
}
WARN(1, "No more dynamic states available for CPU hotplug\n");
@@ -1323,7 +1337,7 @@ static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name,
mutex_lock(&cpuhp_state_mutex);
- if (state == CPUHP_AP_ONLINE_DYN) {
+ if (state == CPUHP_AP_ONLINE_DYN || state == CPUHP_BP_PREPARE_DYN) {
ret = cpuhp_reserve_state(state);
if (ret < 0)
goto out;