This series extends the recently introduced trace remotes
infrastructure, bringing useful features for developers:
* dump_on_panic: Dump the trace remote buffer on system panic.
* dmesg: Redirect remote events to dmesg.
* trace_remote=: Configure a trace_remote from the commandline.
* poll_ms: Modify the polling period.
It also brings a couple of optimisations:
* In-header compressed length support for small events.
* Single work thread for remote polling.
And some misc improvements:
* Use kstrtobool where possible
* Free resources on remote registration failure
Changelog:
v7:
* Check for printk timestamps in dmesg selftest. (Sashiko)
* Touch NMI watchdog in the panic dump loop. (Sashiko)
* Add READ_ONCE()/WRITE_ONCE() for panic_on. (Sashiko)
* Defer dmesg and tracing enabling after all cmdline options are parsed. (Sashiko)
* Guard sysrq panic trigger in dump_on_panic.tc with TRIGGER_PANIC env variable. (Sashiko)
* Rebase on 7.3-rc4
v6 (https://lore.kernel.org/all/20260817135517.3919534-1-vdonnefort@google.com/):
* Replace WARN_ON with pr_warn for buf_size in cmdline parsing. (Sashiko)
* Add READ_ONCE()/WRITE_ONCE() for poll_ms (Sashiko)
* Add support for HAVE_64BIT_ALIGNED_ACCESS arch is set in simple_ring_buffer. (Sashiko)
* Add selftest tracefs file requirements, TMPDIR leak, and awk regex. (Sashiko)
* Rebase on 7.2
v5 (https://lore.kernel.org/all/20260812161340.2417322-1-vdonnefort@google.com/):
* Use seq_buf_str() for safe, properly terminated trace_seq extraction. (Steven)
* Remove destructive dmesg -c from selftests and rely on timestamp matching instead. (Steven)
* Allow several trace_remote=XXX cmdline options.
* Rebase on 7.2-rc7
v4 (https://lore.kernel.org/all/20260804140333.797210-1-vdonnefort@google.com/):
* Rebase on 7.2-rc6
* Use trace_append_boot_param() to parse cmdline options.
* Fix trace_remote_iterator cleanup order for non-consuming iterators
(Sashiko).
v3 (https://lore.kernel.org/all/20260721103603.342266-1-vdonnefort@google.com/):
* Make sure dmesg and panic handlers are using null-terminated
trace_seq.
* Make struct trace_remote more compact
* Fix dump_on_panic test unloaded case (Sashiko)
* Rebase on 7.2-rc4
v2 (https://lore.kernel.org/all/20260605163825.1762953-1-vdonnefort@google.com/):
Sashiko had a few spot-on comments on the v1 which forced me to heavily
re-arrange the series, so I thought it'd be alright to send a v2
already including those changes.
* dump_on_oops -> dump_on_panic
* printk -> dmesg
* Allow to configure poll_ms
* Make the ring_buffer_iter functions panic-friendly
* Gate tracefs .open on remote registration (Sashiko)
* Use irqsave for reader lock (Sashiko)
* Fix iter locking for TRI_DMESG (Sashiko)
* Yield in the dmesg work (Sashiko)
v1 (https://lore.kernel.org/all/20260602171146.2238998-1-vdonnefort@google.com/)
Vincent Donnefort (20):
tracing/remotes: Gate tracefs files opening on trace remote
registration
tracing/remotes: Release tracefs,eventfs on registration failure
tracing/remotes: Use kstrtobool for boolean tracefs files
tracing/remotes: Initialise pos in trace_start()
tracing/remotes: Annotate remote shared fields with
READ_ONCE/WRITE_ONCE
tracing/remotes: Use a single per-remote polling work
tracing/simple_ring_buffer: Add support for compressed length
tracing/remotes: Add dmesg tracefs file
tracing/remotes: selftests: Add a test for the dmesg tracefs file
tracing/remotes: selftests: Prefix hypervisor folder
ring-buffer: Use irqsave for the reader lock in
ring_buffer_poll_remote
ring-buffer: Use panic-friendly locking in ring_buffer_iter interface
ring-buffer: Add ring_buffer_read_remote_meta_page()
ring-buffer: Add kerneldoc for ring_buffer_poll_remote
tracing/remotes: Add dump_on_panic tracefs file
tracing/remotes: selftests: Add a test for the dump_on_panic tracefs
file
tracing/remotes: Add poll_ms tracefs file
tracing/remotes: Add trace_remote cmdline options
Documentation: tracing/remotes: Add detailed tracefs layout
Documentation/kernel-parameters: Add trace_remote
.../admin-guide/kernel-parameters.txt | 19 +
Documentation/trace/remotes.rst | 66 +-
include/linux/ring_buffer.h | 1 +
kernel/trace/ring_buffer.c | 88 +-
kernel/trace/simple_ring_buffer.c | 23 +-
kernel/trace/trace_remote.c | 841 +++++++++++++++---
.../buffer_size.tc | 0
.../test.d/remotes/00hypervisor/dmesg.tc | 11 +
.../remotes/00hypervisor/dump_on_panic.tc | 11 +
.../{hypervisor => 00hypervisor}/hotplug.tc | 0
.../{hypervisor => 00hypervisor}/reset.tc | 0
.../{hypervisor => 00hypervisor}/trace.tc | 0
.../trace_pipe.tc | 0
.../{hypervisor => 00hypervisor}/unloading.tc | 0
.../selftests/ftrace/test.d/remotes/dmesg.tc | 86 ++
.../ftrace/test.d/remotes/dump_on_panic.tc | 50 ++
.../selftests/ftrace/test.d/remotes/functions | 2 +
17 files changed, 1050 insertions(+), 148 deletions(-)
rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/buffer_size.tc (100%)
create mode 100644 tools/testing/selftests/ftrace/test.d/remotes/00hypervisor/dmesg.tc
create mode 100644 tools/testing/selftests/ftrace/test.d/remotes/00hypervisor/dump_on_panic.tc
rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/hotplug.tc (100%)
rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/reset.tc (100%)
rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/trace.tc (100%)
rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/trace_pipe.tc (100%)
rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/unloading.tc (100%)
create mode 100644 tools/testing/selftests/ftrace/test.d/remotes/dmesg.tc
create mode 100644 tools/testing/selftests/ftrace/test.d/remotes/dump_on_panic.tc
base-commit: 93f51579e7df248780214094418f205253383cc5
--
2.56.0.rc1.310.g51773c2048-goog