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McKenney" , Petr Tesarik , Shengming Hu , Yaxiong Tian , Alexei Starovoitov Subject: [GIT PULL] tracing updates for v7.0 Message-ID: <20260213115814.6ac46ad3@gandalf.local.home> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: isuede38t4dia1toeukkc5kmtae6okde X-Rspamd-Server: rspamout04 X-Rspamd-Queue-Id: D922520027 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX18yq5asYLFx7G3RTc8r4ADnmyUHKChDVfk= X-HE-Tag: 1771001905-781074 X-HE-Meta: U2FsdGVkX1+HRwC1e3UXXvtBNrTM+0MAkZtOY4IgHS6P3rrQ0//pepYBn0OhUNJfnISf5NLnWerFypA8o3So8xkfX6nKZXv+19zKd7YdXSV3jGlfuH4+Q8jG6PA2YJL8XNU/EZ1e6919Po1uzuLiGIOtIY4KJLjvZTelZAhfLsgbiDSlz60hc9YI/0mhHI5IjAYuc/95na2tv0O58wf6JkW4TiqqkqdD9RyC6IZtReAeC9pI1Rz8ZP2tfoyNYy6WA9l85es0iX+PF+3Hwa6lkLYxCOshMJkbfZNBgAku98QKBnPFEZoDIA0NlT89MN8Vdat8FSqurVWOIAEgMeuBy5drt7qDQ5ndug0ZlU9uLoIdBsjmLdPmcw== Linus, [ Note, there's two merge conflicts: 1. With BPF code. This PR made tracepoint callbacks preemptable. BPF needs to run on the same CPU until completion. Alexei recommended using rcu_read_lock_dont_migrate() in the BPF callback. This conflicted with some other changes in the BPF tree. 2. With mm tree. This PR moved trace_printk() code out of trace.c and into trace_printk.c. A change in Andrew Morton's mm tree removed the string size parameter from __trace_puts(). That function was one of the functions moved to trace_printk.c. That update now needs to happen in that file instead. The updates in linux-next master branch have the proper merge resolution. ] tracing updates for 7.0: User visible changes: - Add an entry into MAINTAINERS file for RUST versions of code There's now RUST code for tracing and static branches. To differentiate that code from the C code, add entries in for the RUST version (with "[RUST]" around it) so that the right maintainers get notified on changes. - New bitmask-list option added to tracefs When this is set, bitmasks in trace event are not displayed as hex numbers, but instead as lists: e.g. 0-5,7,9 instead of 0000015f - New show_event_filters file in tracefs Instead of having to search all events/*/*/filter for any active filters enabled in the trace instance, the file show_event_filters will list them so that there's only one file that needs to be examined to see if any filters are active. - New show_event_triggers file in tracefs Instead of having to search all events/*/*/trigger for any active triggers enabled in the trace instance, the file show_event_triggers will list them so that there's only one file that needs to be examined to see if any triggers are active. - Have traceoff_on_warning disable trace pintk buffer too Recently recording of trace_printk() could go to other trace instances instead of the top level instance. But if traceoff_on_warning triggers, it doesn't stop the buffer with trace_printk() and that data can easily be lost by being overwritten. Have traceoff_on_warning also disable the instance that has trace_printk() being written to it. - Update the hist_debug file to show what function the field uses When CONFIG_HIST_TRIGGERS_DEBUG is enabled, a hist_debug file exists for every event. This displays the internal data of any histogram enabled for that event. But it is lacking the function that is called to process one of its fields. This is very useful information that was missing when debugging histograms. - Up the histogram stack size from 16 to 31 Stack traces can be used as keys for event histograms. Currently the size of the stack that is stored is limited to just 16 entries. But the storage space in the histogram is 256 bytes, meaning that it can store up to 31 entries (plus one for the count of entries). Instead of letting that space go to waste, up the limit from 16 to 31. This makes the keys much more useful. - Fix permissions of per CPU file buffer_size_kb The per CPU file of buffer_size_kb was incorrectly set to read only in a previous cleanup. It should be writable. - Reset "last_boot_info" if the persistent buffer is cleared The last_boot_info shows address information of a persistent ring buffer if it contains data from a previous boot. It is cleared when recording starts again, but it is not cleared when the buffer is reset. The data is useless after a reset so clear it on reset too. Internal changes: - A change was made to allow tracepoint callbacks to have preemption enabled, and instead be protected by SRCU. This required some updates to the callbacks for perf and BPF. perf needed to disable preemption directly in its callback because it expects preemption disabled in the later code. BPF needed to disable migration, as its code expects to run completely on the same CPU. - Have irq_work wake up other CPU if current CPU is "isolated" When there's a waiter waiting on ring buffer data and a new event happens, an irq work is triggered to wake up that waiter. This is noisy on isolated CPUs (running NO_HZ_FULL). Trigger an IPI to a house keeping CPU instead. - Use proper free of trigger_data instead of open coding it in. - Remove redundant call of event_trigger_reset_filter() It was called immediately in a function that was called right after it. - Workqueue cleanups - Report errors if tracing_update_buffers() were to fail. - Make the enum update workqueue generic for other parts of tracing On boot up, a work queue is created to convert enum names into their numbers in the trace event format files. This work queue can also be used for other aspects of tracing that takes some time and shouldn't be called by the init call code. The blk_trace initialization takes a bit of time. Have the initialization code moved to the new tracing generic work queue function. - Skip kprobe boot event creation call if there's no kprobes defined on cmdline The kprobe initialization to set up kprobes if they are defined on the cmdline requires taking the event_mutex lock. This can be held by other tracing code doing initialization for a long time. Since kprobes added to the kernel command line need to be setup immediately, as they may be tracing early initialization code, they cannot be postponed in a work queue and must be setup in the initcall code. If there's no kprobe on the kernel cmdline, there's no reason to take the mutex and slow down the boot up code waiting to get the lock only to find out there's nothing to do. Simply exit out early if there's no kprobes on the kernel cmdline. If there are kprobes on the cmdline, then someone cares more about tracing over the speed of boot up. - Clean up the trigger code a bit - Move code out of trace.c and into their own files trace.c is now over 11,000 lines of code and has become more difficult to maintain. Start splitting it up so that related code is in their own files. Move all the trace_printk() related code into trace_printk.c. Move the __always_inline stack functions into trace.h. Move the pid filtering code into a new trace_pid.c file. - Better define the max latency and snapshot code The latency tracers have a "max latency" buffer that is a copy of the main buffer and gets swapped with it when a new high latency is detected. This keeps the trace up to the highest latency around where this max_latency buffer is never written to. It is only used to save the last max latency trace. A while ago a snapshot feature was added to tracefs to allow user space to perform the same logic. It could also enable events to trigger a "snapshot" if one of their fields hit a new high. This was built on top of the latency max_latency buffer logic. Because snapshots came later, they were dependent on the latency tracers to be enabled. In reality, the latency tracers depend on the snapshot code and not the other way around. It was just that they came first. Restructure the code and the kconfigs to have the latency tracers depend on snapshot code instead. This actually simplifies the logic a bit and allows to disable more when the latency tracers are not defined and the snapshot code is. - Fix a "false sharing" in the hwlat tracer code The loop to search for latency in hardware was using a variable that could be changed by user space for each sample. If the user change this variable, it could cause a bus contention, and reading that variable can show up as a large latency in the trace causing a false positive. Read this variable at the start of the sample with a READ_ONCE() into a local variable and keep the code from sharing cache lines with readers. - Fix function graph tracer static branch optimization code When only one tracer is defined for function graph tracing, it uses a static branch to call that tracer directly. When another tracer is added, it goes into loop logic to call all the registered callbacks. The code was incorrect when going back to one tracer and never re-enabled the static branch again to do the optimization code. - And other small fixes and cleanups. Please pull the latest trace-v7.0 tree, which can be found at: git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git trace-v7.0 Tag SHA1: 550103013647f1293433ce34d38faa20b0aeb8c9 Head SHA1: 53b2fae90ff01fede6520ca744ed5e8e366497ba Aaron Tomlin (3): tracing: Add bitmask-list option for human-readable bitmask display tracing: Add show_event_filters to expose active event filters tracing: Add show_event_triggers to expose active event triggers Alice Ryhl (1): MAINTAINERS: add Rust files to STATIC BRANCH/CALL and TRACING Colin Lord (1): tracing: Fix false sharing in hwlat get_sample() Guenter Roeck (1): ftrace: Introduce and use ENTRIES_PER_PAGE_GROUP macro Haoyang LIU (1): tracing: Fix indentation of return statement in print_trace_fmt() Marco Crivellari (1): tracing: Replace use of system_wq with system_dfl_wq Masami Hiramatsu (Google) (2): tracing: Fix to set write permission to per-cpu buffer_size_kb tracing: Reset last_boot_info if ring buffer is reset Miaoqian Lin (1): tracing: Properly process error handling in event_hist_trigger_parse() Paul E. McKenney (1): srcu: Fix warning to permit SRCU-fast readers in NMI handlers Petr Tesarik (1): ring-buffer: Use a housekeeping CPU to wake up waiters Shengming Hu (1): function_graph: Restore direct mode when callbacks drop to one Steven Rostedt (29): tracing: Remove redundant call to event_trigger_reset_filter() in event_hist_trigger_parse() tracing: Check the return value of tracing_update_buffers() tracing: Have show_event_trigger/filter format a bit more in columns tracing: Disable trace_printk buffer on warning too tracing: Have hist_debug show what function a field uses tracing: Remove notrace from trace_event_raw_event_synth() tracing: Up the hist stacktrace size from 16 to 31 tracing: Remove duplicate ENABLE_EVENT_STR and DISABLE_EVENT_STR macros tracing: perf: Have perf tracepoint callbacks always disable preemption bpf: Have __bpf_trace_run() use rcu_read_lock_dont_migrate() tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast tracing: Add kerneldoc to trace_event_buffer_reserve() tracing: Have all triggers expect a file parameter tracing: Move tracing_set_filter_buffering() into trace_events_hist.c tracing: Clean up use of trace_create_maxlat_file() tracing: Make tracing_disabled global for tracing system tracing: Make tracing_selftest_running global to the tracing subsystem tracing: Move __trace_buffer_{un}lock_*() functions to trace.h tracing: Move ftrace_trace_stack() out of trace.c and into trace.h tracing: Make printk_trace global for tracing system tracing: Make tracing_update_buffers() take NULL for global_trace tracing: Have trace_printk functions use flags instead of using global_trace tracing: Use system_state in trace_printk_init_buffers() tracing: Move trace_printk functions out of trace.c and into trace_printk.c tracing: Move pid filtering into trace_pid.c tracing: Rename trace_array field max_buffer to snapshot_buffer tracing: Add tracer_uses_snapshot() helper to remove #ifdefs tracing: Better separate SNAPSHOT and MAX_TRACE options tracing: Move d_max_latency out of CONFIG_FSNOTIFY protection Yaxiong Tian (3): tracing: Rename `eval_map_wq` and allow other parts of tracing use it blktrace: Make init_blk_tracer() asynchronous tracing/kprobes: Skip setup_boot_kprobe_events() when no cmdline event ---- Documentation/trace/ftrace.rst | 25 + MAINTAINERS | 15 + include/linux/trace_events.h | 8 +- include/linux/trace_seq.h | 12 +- include/linux/tracepoint.h | 9 +- include/trace/perf.h | 4 +- include/trace/stages/stage3_trace_output.h | 4 +- include/trace/trace_events.h | 4 +- kernel/rcu/srcutree.c | 3 +- kernel/trace/Kconfig | 8 +- kernel/trace/Makefile | 1 + kernel/trace/blktrace.c | 23 +- kernel/trace/bpf_trace.c | 5 +- kernel/trace/fgraph.c | 2 +- kernel/trace/ftrace.c | 7 +- kernel/trace/ring_buffer.c | 24 +- kernel/trace/trace.c | 1059 ++++------------------------ kernel/trace/trace.h | 131 +++- kernel/trace/trace_events.c | 163 ++++- kernel/trace/trace_events_filter.c | 2 +- kernel/trace/trace_events_hist.c | 101 ++- kernel/trace/trace_events_synth.c | 6 +- kernel/trace/trace_events_trigger.c | 62 +- kernel/trace/trace_hwlat.c | 15 +- kernel/trace/trace_kprobe.c | 6 +- kernel/trace/trace_output.c | 30 +- kernel/trace/trace_pid.c | 246 +++++++ kernel/trace/trace_printk.c | 431 +++++++++++ kernel/trace/trace_selftest.c | 10 +- kernel/trace/trace_seq.c | 29 +- kernel/tracepoint.c | 18 +- 31 files changed, 1389 insertions(+), 1074 deletions(-) create mode 100644 kernel/trace/trace_pid.c ---------------------------