diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2017-01-10 14:01:05 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-01-16 13:20:05 +0100 |
| commit | 4205e4786d0b9fc3b4fec7b1910cf645a0468307 (patch) | |
| tree | 685ccb486409197b936c785eb9d173c3edff45a1 /kernel/cpu.c | |
| parent | 7e164ce4e8ecd7e9a58a83750bd3ee03125df154 (diff) | |
| download | linux-4205e4786d0b9fc3b4fec7b1910cf645a0468307.tar.bz2 | |
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/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 22 |
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; |