kernel/linux.git/tools/tracing/rtla/src/common.c, branch v7.2-rc1

rtla: Parse cmdline using libsubcmd

2026-05-28T11:02:48+00:00

Instead of using getopt_long() directly to parse the command line arguments given to an RTLA tool, use libsubcmd's parse_options(). Utilizing libsubcmd for parsing command line arguments has several benefits: - A help message is automatically generated by libsubcmd from the specification, removing the need of writing it by hand. - Options are sorted into groups based on which part of tracing (CPU, thread, auto-analysis, tuning, histogram) they relate to. - Common parsing patterns for numerical and boolean values now share code, with the target variable being stored in the option array. To avoid duplication of the option parsing logic, RTLA-specific macros defining struct option values are created: - RTLA_OPT_* for options common to all tools - OSNOISE_OPT_* and TIMERLAT_OPT_* for options specific to osnoise/timerlat tools - HIST_OPT_* macros for options specific to histogram-based tools. Individual *_parse_args() functions then construct an array out of these macros that is then passed to libsubcmd's parse_options(). All code specific to command line options parsing is moved out of the individual tool files into a new file, cli.c, which also contains the contents of the rtla.c file. A private header, cli_p.h, is added alongside the public header cli.h, so that unit tests are able to test statically declared option callbacks. Minor changes: - The return value of tool-level help option changes to 129, as this is the value set by libsubcmd; this is reflected in affected test cases. The implementation of help for command-level and tracer-level help is set to 129 as well for consistency, and the change is reflected in exit value documentation. - Related to the above, {rtla,osnoise,timerlat}_usage() are marked __noreturn and exit() is removed from after they are called for cleaner code. - The error messages for invalid argument for options --dma-latency and -E/--entries were corrected, fixing off-by-one in the limits. Note that unsetting options (using --no- syntax) is currently not implemented for options that use custom callbacks. For --irq and --thread, it will never be implemented, as they conflict with already existing --no-irq and --no-thread with a different meaning. Assisted-by: Composer:composer-1.5 Link: https://lore.kernel.org/r/20260528103254.2990068-5-tglozar@redhat.com Signed-off-by: Tomas Glozar

rtla: Stop the record trace on interrupt

2026-05-18T09:00:52+00:00

Before, when rtla got a signal, it stopped the main trace but not the record trace. With "--on-end trace", this can lead to save_trace_to_file() failing to keep up, especially on a debug kernel. Plus, it adds post-stoppage noise to the trace file. Signed-off-by: Crystal Wood Fixes: c73cab9dbed0 ("rtla/timerlat_hist: Stop timerlat tracer on signal") Fixes: a4dfce7559d7 ("rtla/timerlat_top: Stop timerlat tracer on signal") Fixes: 3aadb65db5d6 ("rtla/timerlat: Add action on end feature") Link: https://lore.kernel.org/r/20260512173731.2151841-1-crwood@redhat.com Signed-off-by: Tomas Glozar

rtla: Fix segfault on multiple SIGINTs

2026-03-20T13:41:36+00:00

Detach stop_trace() from SIGINT/SIGALRM on tool clean-up to prevent it from crashing RTLA by accessing freed memory. This prevents a crash when multiple SIGINTs are received. Fixes: d6899e560366 ("rtla/timerlat_hist: Abort event processing on second signal") Fixes: 80967b354a76 ("rtla/timerlat_top: Abort event processing on second signal") Reviewed-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260310160725.144443-1-tglozar@redhat.com Signed-off-by: Tomas Glozar

rtla: Handle pthread_create() failure properly

2026-03-11T14:29:50+00:00

Add proper error handling when pthread_create() fails to create the timerlat user-space dispatcher thread. Previously, the code only logged an error message but continued execution, which could lead to undefined behavior when the tool later expects the thread to be running. When pthread_create() returns an error, the function now jumps to the out_trace error path to properly clean up resources and exit. This ensures consistent error handling and prevents the tool from running in an invalid state without the required user-space thread. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260309195040.1019085-10-wander@redhat.com Signed-off-by: Tomas Glozar

rtla: Introduce common_threshold_handler() helper

2026-03-10T09:32:37+00:00

Several functions duplicate the logic for handling threshold actions. When a threshold is reached, these functions stop the trace, perform configured actions, and restart the trace if --on-threshold continue is set. Create common_threshold_handler() to centralize this shared logic and avoid code duplication. The function executes the configured threshold actions and restarts the necessary trace instances when appropriate. Also add should_continue_tracing() helper to encapsulate the check for whether tracing should continue after a threshold event, improving code readability at call sites. In timerlat_top_bpf_main_loop(), use common_params directly instead of casting through timerlat_params when only common fields are needed. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260309195040.1019085-5-wander@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Consolidate nr_cpus usage across all tools

2026-03-09T07:49:16+00:00

sysconf(_SC_NPROCESSORS_CONF) (via get_nprocs_conf) reflects cpu_possible_mask, which is fixed at boot time, so querying it repeatedly is unnecessary. Replace multiple calls to sysconf(_SC_NPROCESSORS_CONF) with a single global nr_cpus variable initialized once at startup. `#pragma once` in timerlat_u.h is needed for pre-C23 compilers to avoid redefinition errors. Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20260306194953.2511960-2-costa.shul@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Generate optstring from long options

2026-03-02T13:53:41+00:00

getopt_long() processes short and long options independently. RTLA, like the majority of applications, uses both short and long variants for each logical option. Since the val member of struct option holds the letter of the short variant, the string of short options can be reconstructed from the array of long options. Add getopt_auto() to generate optstring from an array of long options, eliminating the need to maintain separate short option strings. Signed-off-by: Costa Shulyupin Reviewed-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260108095011.2115719-1-costa.shul@redhat.com Signed-off-by: Tomas Glozar

rtla: Make stop_tracing variable volatile

2026-01-07T14:57:55+00:00

The stop_tracing global variable is accessed from both the signal handler context and the main program flow without synchronization. This creates a potential race condition where compiler optimizations could cache the variable value in registers, preventing the signal handler's updates from being visible to other parts of the program. Add the volatile qualifier to stop_tracing in both common.c and common.h to ensure all accesses to this variable bypass compiler optimizations and read directly from memory. This guarantees that when the signal handler sets stop_tracing, the change is immediately visible to the main program loop, preventing potential hangs or delayed shutdown when termination signals are received. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260106133655.249887-16-wander@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Consolidate -H/--house-keeping option parsing

2026-01-07T14:57:17+00:00

Each rtla tool duplicates parsing of -H/--house-keeping. Migrate the option parsing from individual tools to the common_parse_options(). Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20251209100047.2692515-8-costa.shul@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Consolidate -P/--priority option parsing

2026-01-07T14:57:17+00:00

Each rtla tool duplicates parsing of -P/--priority. Migrate the option parsing from individual tools to the common_parse_options(). Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20251209100047.2692515-7-costa.shul@redhat.com Signed-off-by: Tomas Glozar