kernel/linux.git/tools/tracing/rtla/src/timerlat_bpf.h, branch linux-7.1.y

Merge tag 'trace-rtla-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-04-16T00:48:24+00:00

Pull RTLA updates from Steven Rostedt: - Simplify option parsing Auto-generate getopt_long() optstring for short options from long options array, avoiding the need to specify it manually and reducing the surface for mistakes. - Add unit tests Implement unit tests (make unit-tests) using libcheck, next to existing runtime tests (make check). Currently, three functions from utils.c are tested. - Add --stack-format option In addition to stopping stack pointer decoding (with -s/--stack option) on first unresolvable pointer, allow also skipping unresolvable pointers and displaying everything, configurable with a new option. - Unify number of CPUs into one global variable Use one global variable, nr_cpus, to store the number of CPUs instead of retrieving it and passing it at multiple places. - Fix behavior in various corner cases Make RTLA behave correctly in several corner cases: memory allocation failure, invalid value read from kernel side, thread creation failure, malformed time value input, and read/write failure or interruption by signal. - Improve string handling Simplify several places in the code that handle strings, including parsing of action arguments. A few new helper functions and variables are added for that purpose. - Get rid of magic numbers Few places handling paths use a magic number of 1024. Replace it with MAX_PATH and ARRAY_SIZE() macro. - Unify threshold handling Code that handles response to latency threshold is duplicated between tools, which has led to bugs in the past. Unify it into a new helper as much as possible. - Fix segfault on SIGINT during cleanup The SIGINT handler touches dynamically allocated memory. Detach it before freeing it during cleanup to prevent segmentation fault and discarding of output buffers. Also, properly document SIGINT handling while at it. * tag 'trace-rtla-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (28 commits) Documentation/rtla: Document SIGINT behavior rtla: Fix segfault on multiple SIGINTs rtla/utils: Fix loop condition in PID validation rtla/utils: Fix resource leak in set_comm_sched_attr() rtla/trace: Fix I/O handling in save_trace_to_file() rtla/trace: Fix write loop in trace_event_save_hist() rtla/timerlat: Simplify RTLA_NO_BPF environment variable check rtla: Use str_has_prefix() for option prefix check rtla: Enforce exact match for time unit suffixes rtla: Use str_has_prefix() for prefix checks rtla: Add str_has_prefix() helper function rtla: Handle pthread_create() failure properly rtla/timerlat: Add bounds check for softirq vector rtla: Simplify code by caching string lengths rtla: Replace magic number with MAX_PATH rtla: Introduce common_threshold_handler() helper rtla/actions: Simplify argument parsing rtla: Use strdup() to simplify code rtla: Exit on memory allocation failures during initialization tools/rtla: Remove unneeded nr_cpus from for_each_monitored_cpu ...

rtla: Fix build without libbpf header

2026-03-30T16:44:48+00:00

rtla supports building without libbpf. However, BPF actions patchset [1] adds an include of bpf/libbpf.h into timerlat_bpf.h, which breaks build on systems that don't have libbpf headers installed. This is a leftover from a draft version of the patchset where timerlat_bpf_set_action() (which takes a struct bpf_program * argument) was defined in the header. timerlat_bpf.c already includes bpf/libbpf.h via timerlat.skel.h when libbpf is present. Remove the redundant include to fix build on systems without libbpf headers. [1] https://lore.kernel.org/linux-trace-kernel/20251126144205.331954-1-tglozar@redhat.com/T/ Cc: John Kacur Cc: Luis Goncalves Cc: Crystal Wood Cc: Costa Shulyupin Link: https://patch.msgid.link/20260330091207.16184-1-tglozar@redhat.com Reported-by: Steven Rostedt (Google) Closes: https://lore.kernel.org/linux-trace-kernel/20260329122202.65a8b575@robin/ Fixes: 8cd0f08ac72e ("rtla/timerlat: Support tail call from BPF program") Signed-off-by: Tomas Glozar Reviewed-by: Wander Lairson Costa Signed-off-by: Steven Rostedt (Google)

tools/rtla: Remove unneeded nr_cpus arguments

2026-03-09T07:49:17+00:00

nr_cpus does not change at runtime, so passing it through function arguments is unnecessary. Use the global nr_cpus instead of propagating it via parameters. Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20260306194953.2511960-3-costa.shul@redhat.com Signed-off-by: Tomas Glozar

rtla/timerlat: Add --bpf-action option

2026-01-07T14:57:16+00:00

Add option --bpf-action that allows the user to attach an external BPF program that will be executed via BPF tail call on latency threshold overflow. Executing additional BPF code on latency threshold overflow allows doing low-latency and in-kernel troubleshooting of the cause of the overflow. The option takes an argument, which is a path to a BPF ELF file expected to contain a function named "action_handler" in a section named "tp/timerlat_action" (the section is necessary for libbpf to assign the correct BPF program type to it). Link: https://lore.kernel.org/r/20251126144205.331954-3-tglozar@redhat.com Signed-off-by: Tomas Glozar

rtla/timerlat: Support tail call from BPF program

2026-01-07T14:57:15+00:00

Add a map to the rtla-timerlat BPF program that holds a file descriptor of another BPF program, to be executed on threshold overflow. timerlat_bpf_set_action() is added as an interface to set the program. Link: https://lore.kernel.org/r/20251126144205.331954-2-tglozar@redhat.com Signed-off-by: Tomas Glozar

rtla/timerlat_bpf: Allow resuming tracing

2025-07-25T20:43:56+00:00

Currently, rtla-timerlat BPF program uses a global variable stored in a .bss section to store whether tracing has been stopped. Move the information to a separate map, so that it is easily writable from userspace, and add a function that clears the value, resuming tracing after it has been stopped. Cc: John Kacur Cc: Luis Goncalves Cc: Arnaldo Carvalho de Melo Cc: Chang Yin Cc: Costa Shulyupin Cc: Crystal Wood Cc: Gabriele Monaco Link: https://lore.kernel.org/20250626123405.1496931-4-tglozar@redhat.com Signed-off-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)

rtla/timerlat: Add BPF skeleton to collect samples

2025-03-04T17:35:18+00:00

Add BPF program that attaches to the osnoise:timerlat_sample tracepoint and collects both the summary and the histogram (if requested) into BPF maps (one map of each kind per context). The program is designed to be used for both timerlat-top and timerlat-hist. If using with timerlat-top, the "entries" parameter is set to zero, which prevents the BPF program from recording histogram entries. In that case, the maps for histograms do not have to be created, as the BPF verifier will identify the code using them as unreachable. An IRQ or thread latency threshold might be supplied to stop recording if hit, similar to the timerlat tracer threshold, which stops ftrace tracing if hit. A BPF ringbuffer is used to signal threshold overflow to userspace. In aa-only mode, this is the only function of the BPF program. Cc: John Kacur Cc: Luis Goncalves Cc: Gabriele Monaco Cc: Clark Williams Link: https://lore.kernel.org/20250218145859.27762-5-tglozar@redhat.com Signed-off-by: Tomas Glozar Signed-off-by: Steven Rostedt (Google)