diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index e101b0764b398b2f4869fbdb4c0fcf87b92dee15..58afc83afc9d5a1ba412d8f78d2e3f2d4066e068 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8349,12 +8349,34 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, return ret; } +/* An ioctl call with cmd 0 to the ring buffer file will wake up all waiters */ +static long tracing_buffers_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct ftrace_buffer_info *info = file->private_data; + struct trace_iterator *iter = &info->iter; + + if (cmd) + return -ENOIOCTLCMD; + + mutex_lock(&trace_types_lock); + + iter->wait_index++; + /* Make sure the waiters see the new wait_index */ + smp_wmb(); + + ring_buffer_wake_waiters(iter->array_buffer->buffer, iter->cpu_file); + + mutex_unlock(&trace_types_lock); + return 0; +} + static const struct file_operations tracing_buffers_fops = { .open = tracing_buffers_open, .read = tracing_buffers_read, .poll = tracing_buffers_poll, .release = tracing_buffers_release, .splice_read = tracing_buffers_splice_read, + .unlocked_ioctl = tracing_buffers_ioctl, .llseek = no_llseek, };