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

rtla: Fix parsing of multi-character short options

2026-06-04T08:53:25+00:00

A bug was reported where the parsing of multi-character short options, be it a short option with an argument specified without space (e.g. "-p100") or multiple short options in one argument (e.g. -un), ignores options specific to individual tools. Furthermore, if the rest of the option is supposed to be an argument, it gets reinterpreted as a string of options. For example, -p100 gets interpreted as -100, which is due to hackish implementation read as --no-thread --no-irq --no-irq with timerlat hist, causing rtla to error out: $ rtla timerlat hist -p100 no-irq and no-thread set, there is nothing to do here This behavior is caused by getopt_long() being called twice on each argument, once in common_parse_options(), once in [tool]_parse_args(): - common_parse_options() calls getopt_long() with an array of options common for all rtla tools, while suppressing errors (opterr = 0). - If the option fails to parse, common_parse_options() returns 0. - If 0 is returned from common_parse_options(), [tool]_parse_args() calls getopt_long() again, with its own set of options. * [tool] means one of {osnoise,timerlat}_{top,hist} At least in glibc, getopt_long() increments its internal nextchar variable even if the option is not recognized. That means that in the case of "-p100", common_parse_options() sets nextchar pointing to '1', and timerlat_hist_parse_args() sees '1', not 'p'; the same then repeats for the first and second '0'. As there is no way to restore the correct internal state of getopt_long() reliably, fix the issue by merging the common options back to the longopt array and option string of the [tool]_parse_args() functions using a macro; only the switch part is left in the original function, which is renamed to set_common_option(). Fixes: 850cd24cb6d6 ("tools/rtla: Add common_parse_options()") Reported-by: John Kacur Tested-by: John Kacur Link: https://lore.kernel.org/r/20260602125506.3325345-1-tglozar@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: Remove unneeded nr_cpus from for_each_monitored_cpu

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

nr_cpus does not change at runtime, so passing it through the macro argument is unnecessary. Remove the argument and use the global nr_cpus instead. Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20260306194953.2511960-5-costa.shul@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: Add common_parse_options()

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

Each rtla tool duplicates parsing of many common options. This creates maintenance overhead and risks inconsistencies when updating these options. Add common_parse_options() to centralize parsing of options used across all tools. Common options to be migrated in future patches. Changes since v1: - restore opterr Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20251209100047.2692515-1-costa.shul@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Add common_usage()

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

The rtla tools have significant code quadruplication in their usage functions. Each tool implements its own version of the same help text formatting and option descriptions, leading to maintenance overhead and inconsistencies. Documentation/tools/rtla/common_options.rst lists 14 common options. Add common_usage() infrastructure to consolidate help formatting. Subsequent patches will extend this to handle other common options. The refactored output is almost identical to the original, with the following changes: - add square brackets to specify optionality: `usage: [rtla] ...` - remove `-q` from timerlat hist because hist tools don't support it - minor spacing Signed-off-by: Costa Shulyupin Link: https://lore.kernel.org/r/20251124063204.845425-1-costa.shul@redhat.com Signed-off-by: Tomas Glozar

rtla: Set stop threshold after all instances are enabled

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

This avoids startup races where one of the instances hit a threshold before all instances were enabled, and thus tracing stops without the relevant event. In particular, this is not uncommon with the tests that set a very tight threshold and then complain if there's no analysis. This also ensures that we don't stop tracing during a warmup. The downside is a small chance of having an event over the threshold early in the output, without stopping on it, which could cause user confusion. This should be less likely if the warmup feature is used, but that doesn't eliminate the race window, just the odds of an unusual spike right at that moment. Signed-off-by: Crystal Wood Link: https://lore.kernel.org/r/20251112152529.956778-6-crwood@redhat.com Signed-off-by: Tomas Glozar

tools/rtla: Add for_each_monitored_cpu() helper

2025-11-20T12:15:53+00:00

The rtla tools have many instances of iterating over CPUs while checking if they are monitored. Add a for_each_monitored_cpu() helper macro to make the code more readable and reduce code duplication. Signed-off-by: Costa Shulyupin Reviewed-by: Tomas Glozar Link: https://lore.kernel.org/r/20251002123553.389467-1-costa.shul@redhat.com Signed-off-by: Tomas Glozar