Commit-ID: 4205e4786d0b9fc3b4fec7b1910cf645a0468307 Gitweb: http://git.kernel.org/tip/4205e4786d0b9fc3b4fec7b1910cf645a0468307 Author: Thomas Gleixner <[email protected]> AuthorDate: Tue, 10 Jan 2017 14:01:05 +0100 Committer: Thomas Gleixner <[email protected]> CommitDate: Mon, 16 Jan 2017 13:20:05 +0100
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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Reviewed-by: Mathieu Desnoyers <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Sebastian Sewior <[email protected]> Cc: Steven Rostedt <[email protected]> Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1701101353010.3401@nanos Signed-off-by: Thomas Gleixner <[email protected]> --- include/linux/cpuhotplug.h | 2 ++ kernel/cpu.c | 22 ++++++++++++++++++---- 2 files changed, 20 insertions(+), 4 deletions(-) diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 20bfefb..d936a00 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -74,6 +74,8 @@ enum cpuhp_state { CPUHP_ZCOMP_PREPARE, CPUHP_TIMERS_DEAD, CPUHP_MIPS_SOC_PREPARE, + CPUHP_BP_PREPARE_DYN, + CPUHP_BP_PREPARE_DYN_END = CPUHP_BP_PREPARE_DYN + 20, CPUHP_BRINGUP_CPU, CPUHP_AP_IDLE_DEAD, CPUHP_AP_OFFLINE, diff --git a/kernel/cpu.c b/kernel/cpu.c index f75c4d0..c475063 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;
