diff options
| -rw-r--r-- | kernel/stop_machine.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index c530bc5be7cf..84571e09c907 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -20,6 +20,7 @@ #include <linux/kallsyms.h> #include <linux/smpboot.h> #include <linux/atomic.h> +#include <linux/lglock.h> /* * Structure to determine completion condition and record errors. May @@ -43,6 +44,14 @@ static DEFINE_PER_CPU(struct cpu_stopper, cpu_stopper); static DEFINE_PER_CPU(struct task_struct *, cpu_stopper_task); static bool stop_machine_initialized = false; +/* + * Avoids a race between stop_two_cpus and global stop_cpus, where + * the stoppers could get queued up in reverse order, leading to + * system deadlock. Using an lglock means stop_two_cpus remains + * relatively cheap. + */ +DEFINE_STATIC_LGLOCK(stop_cpus_lock); + static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo) { memset(done, 0, sizeof(*done)); @@ -276,6 +285,7 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void * return -ENOENT; } + lg_local_lock(&stop_cpus_lock); /* * Queuing needs to be done by the lowest numbered CPU, to ensure * that works are always queued in the same order on every CPU. @@ -284,6 +294,7 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void * smp_call_function_single(min(cpu1, cpu2), &irq_cpu_stop_queue_work, &call_args, 0); + lg_local_unlock(&stop_cpus_lock); preempt_enable(); wait_for_completion(&done.completion); @@ -335,10 +346,10 @@ static void queue_stop_cpus_work(const struct cpumask *cpumask, * preempted by a stopper which might wait for other stoppers * to enter @fn which can lead to deadlock. */ - preempt_disable(); + lg_global_lock(&stop_cpus_lock); for_each_cpu(cpu, cpumask) cpu_stop_queue_work(cpu, &per_cpu(stop_cpus_work, cpu)); - preempt_enable(); + lg_global_unlock(&stop_cpus_lock); } static int __stop_cpus(const struct cpumask *cpumask, |