diff options
| -rw-r--r-- | kernel/smp.c | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/kernel/smp.c b/kernel/smp.c index e6c1d839c187..f6f8529a8003 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -871,15 +871,14 @@ static void smp_call_function_many_cond(const struct cpumask *mask, unsigned int scf_flags, smp_cond_func_t cond_func) { - int cpu, last_cpu, this_cpu = smp_processor_id(); struct cpumask *cpumask, *task_mask; bool wait = scf_flags & SCF_WAIT; struct call_function_data *cfd; + int cpu, last_cpu, this_cpu; bool run_remote = false; int nr_cpus = 0; - lockdep_assert_preemption_disabled(); - + this_cpu = get_cpu(); cfd = this_cpu_ptr(&cfd_data); task_mask = smp_task_ipi_mask(current); if (task_mask) @@ -965,6 +964,16 @@ static void smp_call_function_many_cond(const struct cpumask *mask, local_irq_restore(flags); } + /* + * The IPI work has been queued and dispatched. On PREEMPT kernels, + * tasks created through dup_task_struct() have task-local wait masks. + * The boot init_task can fall back to cfd->cpumask when the mask is + * not inlined, but other tasks still use task-local masks and cannot + * overwrite it. On !PREEMPT kernels, preempt_enable() cannot schedule + * another task, so the per-CPU mask remains protected. + */ + put_cpu(); + if (run_remote && wait) { for_each_cpu(cpu, cpumask) { call_single_data_t *csd; @@ -977,15 +986,14 @@ static void smp_call_function_many_cond(const struct cpumask *mask, /** * smp_call_function_many() - Run a function on a set of CPUs. - * @mask: The set of cpus to run on (only runs on online subset). - * @func: The function to run. This must be fast and non-blocking. - * @info: An arbitrary pointer to pass to the function. - * @wait: If true, wait (atomically) until function has completed - * on other CPUs. + * @mask: The set of cpus to run on (only runs on online subset). + * @func: The function to run. This must be fast and non-blocking. + * @info: An arbitrary pointer to pass to the function. + * @wait: If true, wait (atomically) until function has completed + * on other CPUs. * * You must not call this function with disabled interrupts or from a - * hardware interrupt handler or from a bottom half handler. Preemption - * must be disabled when calling this function. + * hardware interrupt handler or from a bottom half handler. * * @func is not called on the local CPU even if @mask contains it. Consider * using on_each_cpu_cond_mask() instead if this is not desirable. |