diff options
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 465989585135..95ae7c4e5835 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6712,6 +6712,22 @@ static int tracing_wait_pipe(struct file *filp) return 1; } +static bool update_last_data_if_empty(struct trace_array *tr) +{ + if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) + return false; + + if (!ring_buffer_empty(tr->array_buffer.buffer)) + return false; + + /* + * If the buffer contains the last boot data and all per-cpu + * buffers are empty, reset it from the kernel side. + */ + update_last_data(tr); + return true; +} + /* * Consumer reader. */ @@ -6743,6 +6759,9 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, } waitagain: + if (update_last_data_if_empty(iter->tr)) + return 0; + sret = tracing_wait_pipe(filp); if (sret <= 0) return sret; @@ -8321,6 +8340,9 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, if (ret < 0) { if (trace_empty(iter) && !iter->closed) { + if (update_last_data_if_empty(iter->tr)) + return 0; + if ((filp->f_flags & O_NONBLOCK)) return -EAGAIN; @@ -8662,10 +8684,6 @@ static int tracing_buffers_mmap(struct file *filp, struct vm_area_struct *vma) if (iter->tr->flags & TRACE_ARRAY_FL_MEMMAP) return -ENODEV; - /* Currently the boot mapped buffer is not supported for mmap */ - if (iter->tr->flags & TRACE_ARRAY_FL_BOOT) - return -ENODEV; - ret = get_snapshot_map(iter->tr); if (ret) return ret; |