arm_pmu: add armpmu_alloc_atomic()

In ACPI systems, we don't know the makeup of CPUs until we hotplug them
on, and thus have to allocate the PMU datastructures at hotplug time.
Thus, we must use GFP_ATOMIC allocations.

Let's add an armpmu_alloc_atomic() that we can use in this case.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

3 files changed, 16 insertions, 4 deletions

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 373dfd7d8a1d..4f73c5e8d623 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -760,18 +760,18 @@ static void cpu_pmu_destroy(struct arm_pmu *cpu_pmu)
                                             &cpu_pmu->node);
 }
 
-struct arm_pmu *armpmu_alloc(void)
+static struct arm_pmu *__armpmu_alloc(gfp_t flags)
 {
         struct arm_pmu *pmu;
         int cpu;
 
-        pmu = kzalloc(sizeof(*pmu), GFP_KERNEL);
+        pmu = kzalloc(sizeof(*pmu), flags);
         if (!pmu) {
                 pr_info("failed to allocate PMU device!\n");
                 goto out;
         }
 
-        pmu->hw_events = alloc_percpu(struct pmu_hw_events);
+        pmu->hw_events = alloc_percpu_gfp(struct pmu_hw_events, flags);
         if (!pmu->hw_events) {
                 pr_info("failed to allocate per-cpu PMU data.\n");
                 goto out_free_pmu;
@@ -817,6 +817,17 @@ out:
         return NULL;
 }
 
+struct arm_pmu *armpmu_alloc(void)
+{
+        return __armpmu_alloc(GFP_KERNEL);
+}
+
+struct arm_pmu *armpmu_alloc_atomic(void)
+{
+        return __armpmu_alloc(GFP_ATOMIC);
+}
+
+
 void armpmu_free(struct arm_pmu *pmu)
 {
         free_percpu(pmu->hw_events);
diff --git a/drivers/perf/arm_pmu_acpi.c b/drivers/perf/arm_pmu_acpi.c
index 705f1a390e31..30c5f2bbce59 100644
--- a/drivers/perf/arm_pmu_acpi.c
+++ b/drivers/perf/arm_pmu_acpi.c
@@ -127,7 +127,7 @@ static struct arm_pmu *arm_pmu_acpi_find_alloc_pmu(void)
                 return pmu;
         }
 
-        pmu = armpmu_alloc();
+        pmu = armpmu_alloc_atomic();
         if (!pmu) {
                 pr_warn("Unable to allocate PMU for CPU%d\n",
                         smp_processor_id());
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index 899bc7ef0881..1f8bb83ef42f 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -157,6 +157,7 @@ static inline int arm_pmu_acpi_probe(armpmu_init_fn init_fn) { return 0; }
 
 /* Internal functions only for core arm_pmu code */
 struct arm_pmu *armpmu_alloc(void);
+struct arm_pmu *armpmu_alloc_atomic(void);
 void armpmu_free(struct arm_pmu *pmu);
 int armpmu_register(struct arm_pmu *pmu);
 int armpmu_request_irq(struct arm_pmu *armpmu, int cpu);