/**
* lib_ring_buffer_cpu_hp_callback - CPU hotplug callback
* @nb: notifier block
* @action: hotplug action to take
* @hcpu: CPU number
*
* Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
*/
static
int lib_ring_buffer_cpu_hp_callback(struct notifier_block *nb,
unsigned long action,
void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu;
struct channel_backend *chanb = container_of(nb, struct channel_backend,
cpu_hp_notifier);
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);
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
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 NOTIFY_BAD;
}
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
/* No need to do a buffer switch here, because it will happen
* when tracing is stopped, or will be done by switch timer CPU
* DEAD callback. */
break;
}
return NOTIFY_OK;
}
/*
* 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;
}
/**
* channel_backend_init - initialize a channel backend
* @chanb: channel backend
* @name: channel name
* @config: client ring buffer configuration
* @parent: dentry of parent directory, %NULL for root directory
* @subbuf_size: size of sub-buffers (> page size, power of 2)
* @num_subbuf: number of sub-buffers (power of 2)
* @lttng_ust_shm_handle: shared memory handle
* @stream_fds: stream file descriptors.
*
* Returns channel pointer if successful, %NULL otherwise.
*
* Creates per-cpu channel buffers using the sizes and attributes
* specified. The created channel buffer files will be named
* name_0...name_N-1. File permissions will be %S_IRUSR.
*
* Called with CPU hotplug disabled.
*/
int channel_backend_init(struct channel_backend *chanb,
const char *name,
const struct lttng_ust_lib_ring_buffer_config *config,
size_t subbuf_size, size_t num_subbuf,
struct lttng_ust_shm_handle *handle,
const int *stream_fds)
{
struct channel *chan = caa_container_of(chanb, struct channel, backend);
unsigned int i;
int ret;
size_t shmsize = 0, num_subbuf_alloc;
long page_size;
if (!name)
return -EPERM;
page_size = sysconf(_SC_PAGE_SIZE);
if (page_size <= 0) {
return -ENOMEM;
}
/* Check that the subbuffer size is larger than a page. */
if (subbuf_size < page_size)
return -EINVAL;
/*
* Make sure the number of subbuffers and subbuffer size are
* power of 2, and nonzero.
*/
if (!subbuf_size || (subbuf_size & (subbuf_size - 1)))
return -EINVAL;
if (!num_subbuf || (num_subbuf & (num_subbuf - 1)))
return -EINVAL;
/*
* Overwrite mode buffers require at least 2 subbuffers per
* buffer.
*/
if (config->mode == RING_BUFFER_OVERWRITE && num_subbuf < 2)
return -EINVAL;
ret = subbuffer_id_check_index(config, num_subbuf);
if (ret)
return ret;
chanb->buf_size = num_subbuf * subbuf_size;
chanb->subbuf_size = subbuf_size;
chanb->buf_size_order = get_count_order(chanb->buf_size);
chanb->subbuf_size_order = get_count_order(subbuf_size);
chanb->num_subbuf_order = get_count_order(num_subbuf);
chanb->extra_reader_sb =
(config->mode == RING_BUFFER_OVERWRITE) ? 1 : 0;
chanb->num_subbuf = num_subbuf;
strncpy(chanb->name, name, NAME_MAX);
chanb->name[NAME_MAX - 1] = '\0';
memcpy(&chanb->config, config, sizeof(*config));
/* Per-cpu buffer size: control (prior to backend) */
shmsize = offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer));
shmsize += sizeof(struct lttng_ust_lib_ring_buffer);
/* Per-cpu buffer size: backend */
/* num_subbuf + 1 is the worse case */
num_subbuf_alloc = num_subbuf + 1;
shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp));
shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc;
shmsize += offset_align(shmsize, page_size);
shmsize += subbuf_size * num_subbuf_alloc;
shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages));
shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages) * num_subbuf_alloc;
shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_subbuffer));
shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_subbuffer) * num_subbuf;
/* Per-cpu buffer size: control (after backend) */
shmsize += offset_align(shmsize, __alignof__(struct commit_counters_hot));
shmsize += sizeof(struct commit_counters_hot) * num_subbuf;
shmsize += offset_align(shmsize, __alignof__(struct commit_counters_cold));
shmsize += sizeof(struct commit_counters_cold) * num_subbuf;
if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
struct lttng_ust_lib_ring_buffer *buf;
/*
* We need to allocate for all possible cpus.
*/
for_each_possible_cpu(i) {
struct shm_object *shmobj;
shmobj = shm_object_table_alloc(handle->table, shmsize,
SHM_OBJECT_SHM, stream_fds[i]);
if (!shmobj)
goto end;
align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer));
set_shmp(chanb->buf[i].shmp, zalloc_shm(shmobj, sizeof(struct lttng_ust_lib_ring_buffer)));
buf = shmp(handle, chanb->buf[i].shmp);
if (!buf)
goto end;
set_shmp(buf->self, chanb->buf[i].shmp._ref);
ret = lib_ring_buffer_create(buf, chanb, i,
handle, shmobj);
if (ret)
goto free_bufs; /* cpu hotplug locked */
}
} else {
/**
* channel_backend_init - initialize a channel backend
* @chanb: channel backend
* @name: channel name
* @config: client ring buffer configuration
* @priv: client private data
* @parent: dentry of parent directory, %NULL for root directory
* @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2)
* @num_subbuf: number of sub-buffers (power of 2)
*
* Returns channel pointer if successful, %NULL otherwise.
*
* Creates per-cpu channel buffers using the sizes and attributes
* specified. The created channel buffer files will be named
* name_0...name_N-1. File permissions will be %S_IRUSR.
*
* Called with CPU hotplug disabled.
*/
int channel_backend_init(struct channel_backend *chanb,
const char *name,
const struct lib_ring_buffer_config *config,
void *priv, size_t subbuf_size, size_t num_subbuf)
{
struct channel *chan = container_of(chanb, struct channel, backend);
unsigned int i;
int ret;
if (!name)
return -EPERM;
/* Check that the subbuffer size is larger than a page. */
if (subbuf_size < PAGE_SIZE)
return -EINVAL;
/*
* Make sure the number of subbuffers and subbuffer size are
* power of 2 and nonzero.
*/
if (!subbuf_size || (subbuf_size & (subbuf_size - 1)))
return -EINVAL;
if (!num_subbuf || (num_subbuf & (num_subbuf - 1)))
return -EINVAL;
/*
* Overwrite mode buffers require at least 2 subbuffers per
* buffer.
*/
if (config->mode == RING_BUFFER_OVERWRITE && num_subbuf < 2)
return -EINVAL;
ret = subbuffer_id_check_index(config, num_subbuf);
if (ret)
return ret;
chanb->priv = priv;
chanb->buf_size = num_subbuf * subbuf_size;
chanb->subbuf_size = subbuf_size;
chanb->buf_size_order = get_count_order(chanb->buf_size);
chanb->subbuf_size_order = get_count_order(subbuf_size);
chanb->num_subbuf_order = get_count_order(num_subbuf);
chanb->extra_reader_sb =
(config->mode == RING_BUFFER_OVERWRITE) ? 1 : 0;
chanb->num_subbuf = num_subbuf;
strlcpy(chanb->name, name, NAME_MAX);
memcpy(&chanb->config, config, sizeof(chanb->config));
if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
if (!zalloc_cpumask_var(&chanb->cpumask, GFP_KERNEL))
return -ENOMEM;
}
if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
/* Allocating the buffer per-cpu structures */
chanb->buf = alloc_percpu(struct lib_ring_buffer);
if (!chanb->buf)
goto free_cpumask;
#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();
#else
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 {
