Hi Steve,
On 13.12.23 01:15, Steven Rostedt wrote:
On Wed, 13 Dec 2023 00:04:45 +0000
Alexander Graf <graf@xxxxxxxxxx> wrote:
With KHO (Kexec HandOver), we want to preserve trace buffers across
kexec. To carry over their state between kernels, the kernel needs a
common handle for them that exists on both sides. As handle we introduce
names for ring buffers. In a follow-up patch, the kernel can then use
these names to recover buffer contents for specific ring buffers.
Is there a way to use the trace_array name instead?
The trace_array is the structure that represents each tracing instance. And
it already has a name field. And if you can get the associated ring buffer
from that too.
struct trace_array *tr;
tr->array_buffer.buffer
tr->name
When you do: mkdir /sys/kernel/tracing/instance/foo
You create a new trace_array instance where tr->name = "foo" and allocates
the buffer for it as well.
The name in the ring buffer is pretty much just a copy of the trace
array name. I use it to reconstruct which buffer we're actually
referring to inside __ring_buffer_alloc().
I'm all ears for alternative suggestions. I suppose we could pass tr as
argument to ring_buffer_alloc() instead of the name?
Alex
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