From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 30 Jul 2025 23:16:58 +0000 (-0700)
Subject: Merge tag 'trace-ringbuffer-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git... 
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d50b07d05ca53fdb6c6d1581b9084c09d4e98f54;p=thirdparty%2Fkernel%2Flinux.git

Merge tag 'trace-ringbuffer-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull ring-buffer updates from Steven Rostedt:

 - Rewind persistent ring buffer on boot

   When the persistent ring buffer is being used for live kernel tracing
   and the system crashes, the tool that is reading the trace may not
   have recorded the data when the system crashed.

   Although the persistent ring buffer still has that data, when reading
   it after a reboot, it will start where it left off. That is, what was
   read will not be accessible.

   Instead, on reboot, have the persistent ring buffer restart where the
   data starts and this will allow the tooling to recover what was lost
   when the crash occurred.

 - Remove the ring_buffer_read_prepare_sync() logic

   Reading the trace file required stopping writing to the ring buffer
   as the trace file is only an iterator and does not consume what it
   read. It was originally not safe to read the ring buffer in this mode
   and required disabling writing. The ring_buffer_read_prepare_sync()
   logic was used to stop each per_cpu ring buffer, call
   synchronize_rcu() and then start the iterator. This was used instead
   of calling synchronize_rcu() for each per_cpu buffer.

   Today, the iterator has been updated where it is safe to read the
   trace file while writing to the ring buffer is still occurring. There
   is no more need to do this synchronization and it is causing large
   delays on machines with many CPUs. Remove this unneeded
   synchronization.

 - Make static string array a constant in show_irq_str()

   Making the string array into a constant has shown to decrease code
   text/data size.

* tag 'trace-ringbuffer-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Make the const read-only 'type' static
  ring-buffer: Remove ring_buffer_read_prepare_sync()
  tracing: ring_buffer: Rewind persistent ring buffer on reboot
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d50b07d05ca53fdb6c6d1581b9084c09d4e98f54