Adapt lttng-modules to Linux 4.10 cpu hotplug state machine

[lttng-modules.git] / lib / ringbuffer / ring_buffer_backend.c

diff --git a/lib/ringbuffer/ring_buffer_backend.c b/lib/ringbuffer/ring_buffer_backend.c
index 27554a1e46b447464b81f48c48d02eb87906a490..f760836cfe50032e18c9d3774a0e1cd7c6338ed5 100644 (file)
--- a/lib/ringbuffer/ring_buffer_backend.c
+++ b/lib/ringbuffer/ring_buffer_backend.c
@@ -249,7 +249,42 @@ void channel_backend_reset(struct channel_backend *chanb)
        chanb->start_tsc = config->cb.ring_buffer_clock_read(chan);
 }
 
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
+
+/*
+ * No need to implement a "dead" callback to do a buffer switch here,
+ * because it will happen when tracing is stopped, or will be done by
+ * switch timer CPU DEAD callback.
+ * We don't free buffers when CPU go away, because it would make trace
+ * data vanish, which is unwanted.
+ */
+int lttng_cpuhp_rb_backend_prepare(unsigned int cpu,
+               struct lttng_cpuhp_node *node)
+{
+       struct channel_backend *chanb = container_of(node,
+                       struct channel_backend, cpuhp_prepare);
+       const struct lib_ring_buffer_config *config = &chanb->config;
+       struct lib_ring_buffer *buf;
+       int ret;
+
+       CHAN_WARN_ON(chanb, config->alloc == RING_BUFFER_ALLOC_GLOBAL);
+
+       buf = per_cpu_ptr(chanb->buf, cpu);
+       ret = lib_ring_buffer_create(buf, chanb, cpu);
+       if (ret) {
+               printk(KERN_ERR
+                 "ring_buffer_cpu_hp_callback: cpu %d "
+                 "buffer creation failed\n", cpu);
+               return ret;
+       }
+       return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_cpuhp_rb_backend_prepare);
+
+#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
+
 #ifdef CONFIG_HOTPLUG_CPU
+
 /**
  *     lib_ring_buffer_cpu_hp_callback - CPU hotplug callback
  *     @nb: notifier block
@@ -293,8 +328,11 @@ int lib_ring_buffer_cpu_hp_callback(struct notifier_block *nb,
        }
        return NOTIFY_OK;
 }
+
 #endif
 
+#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
+
 /**
  * channel_backend_init - initialize a channel backend
  * @chanb: channel backend
@@ -371,39 +409,50 @@ int channel_backend_init(struct channel_backend *chanb,
                if (!chanb->buf)
                        goto free_cpumask;
 
-               /*
-                * In case of non-hotplug cpu, if the ring-buffer is allocated
-                * in early initcall, it will not be notified of secondary cpus.
-                * In that off case, we need to allocate for all possible cpus.
-                */
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
+               chanb->cpuhp_prepare.component = LTTNG_RING_BUFFER_BACKEND;
+               ret = cpuhp_state_add_instance(lttng_rb_hp_prepare,
+                       &chanb->cpuhp_prepare.node);
+               if (ret)
+                       goto free_bufs;
+#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
+
+               {
+                       /*
+                        * In case of non-hotplug cpu, if the ring-buffer is allocated
+                        * in early initcall, it will not be notified of secondary cpus.
+                        * In that off case, we need to allocate for all possible cpus.
+                        */
 #ifdef CONFIG_HOTPLUG_CPU
-               /*
-                * buf->backend.allocated test takes care of concurrent CPU
-                * hotplug.
-                * Priority higher than frontend, so we create the ring buffer
-                * before we start the timer.
-                */
-               chanb->cpu_hp_notifier.notifier_call =
-                               lib_ring_buffer_cpu_hp_callback;
-               chanb->cpu_hp_notifier.priority = 5;
-               register_hotcpu_notifier(&chanb->cpu_hp_notifier);
-
-               get_online_cpus();
-               for_each_online_cpu(i) {
-                       ret = lib_ring_buffer_create(per_cpu_ptr(chanb->buf, i),
-                                                chanb, i);
-                       if (ret)
-                               goto free_bufs; /* cpu hotplug locked */
-               }
-               put_online_cpus();
+                       /*
+                        * buf->backend.allocated test takes care of concurrent CPU
+                        * hotplug.
+                        * Priority higher than frontend, so we create the ring buffer
+                        * before we start the timer.
+                        */
+                       chanb->cpu_hp_notifier.notifier_call =
+                                       lib_ring_buffer_cpu_hp_callback;
+                       chanb->cpu_hp_notifier.priority = 5;
+                       register_hotcpu_notifier(&chanb->cpu_hp_notifier);
+
+                       get_online_cpus();
+                       for_each_online_cpu(i) {
+                               ret = lib_ring_buffer_create(per_cpu_ptr(chanb->buf, i),
+                                                        chanb, i);
+                               if (ret)
+                                       goto free_bufs; /* cpu hotplug locked */
+                       }
+                       put_online_cpus();
 #else
-               for_each_possible_cpu(i) {
-                       ret = lib_ring_buffer_create(per_cpu_ptr(chanb->buf, i),
-                                                chanb, i);
-                       if (ret)
-                               goto free_bufs; /* cpu hotplug locked */
-               }
+                       for_each_possible_cpu(i) {
+                               ret = lib_ring_buffer_create(per_cpu_ptr(chanb->buf, i),
+                                                        chanb, i);
+                               if (ret)
+                                       goto free_bufs;
+                       }
 #endif
+               }
+#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
        } else {
                chanb->buf = kzalloc(sizeof(struct lib_ring_buffer), GFP_KERNEL);
                if (!chanb->buf)
@@ -418,17 +467,24 @@ int channel_backend_init(struct channel_backend *chanb,
 
 free_bufs:
        if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
+               ret = cpuhp_state_remove_instance(lttng_rb_hp_prepare,
+                               &chanb->cpuhp_prepare.node);
+               WARN_ON(ret);
+#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
+#ifdef CONFIG_HOTPLUG_CPU
+               put_online_cpus();
+               unregister_hotcpu_notifier(&chanb->cpu_hp_notifier);
+#endif
+#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
                for_each_possible_cpu(i) {
-                       struct lib_ring_buffer *buf = per_cpu_ptr(chanb->buf, i);
+                       struct lib_ring_buffer *buf =
+                               per_cpu_ptr(chanb->buf, i);
 
                        if (!buf->backend.allocated)
                                continue;
                        lib_ring_buffer_free(buf);
                }
-#ifdef CONFIG_HOTPLUG_CPU
-               put_online_cpus();
-               unregister_hotcpu_notifier(&chanb->cpu_hp_notifier);
-#endif
                free_percpu(chanb->buf);
        } else
                kfree(chanb->buf);
@@ -448,8 +504,17 @@ void channel_backend_unregister_notifiers(struct channel_backend *chanb)
 {
        const struct lib_ring_buffer_config *config = &chanb->config;
 
-       if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
+       if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
+               int ret;
+
+               ret = cpuhp_state_remove_instance(lttng_rb_hp_prepare,
+                               &chanb->cpuhp_prepare.node);
+               WARN_ON(ret);
+#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
                unregister_hotcpu_notifier(&chanb->cpu_hp_notifier);
+#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
+       }
 }
 
 /**