kernel/linux.git/tools/tracing/rtla/src/utils.c, branch v7.1-rc5

rtla/utils: Fix loop condition in PID validation

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

The procfs_is_workload_pid() function iterates through a directory entry name to validate if it represents a process ID. The loop condition checks if the pointer t_name is non-NULL, but since incrementing a pointer never makes it NULL, this condition is always true within the loop's context. Although the inner isdigit() check catches the NUL terminator and breaks out of the loop, the condition is semantically misleading and not idiomatic for C string processing. Correct the loop condition from checking the pointer (t_name) to checking the character it points to (*t_name). This ensures the loop terminates when the NUL terminator is reached, aligning with standard C string iteration practices. While the original code functioned correctly due to the existing character validation, this change improves code clarity and maintainability. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260309195040.1019085-19-wander@redhat.com Signed-off-by: Tomas Glozar

rtla/utils: Fix resource leak in set_comm_sched_attr()

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

The set_comm_sched_attr() function opens the /proc directory via opendir() but fails to call closedir() on its successful exit path. If the function iterates through all processes without error, it returns 0 directly, leaking the DIR stream pointer. Fix this by refactoring the function to use a single exit path. A retval variable is introduced to track the success or failure status. All exit points now jump to a unified out label that calls closedir() before the function returns, ensuring the resource is always freed. Fixes: dada03db9bb19 ("rtla: Remove procps-ng dependency") Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260309195040.1019085-18-wander@redhat.com Signed-off-by: Tomas Glozar

rtla: Enforce exact match for time unit suffixes

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

The parse_ns_duration() function currently uses prefix matching for detecting time units. This approach is problematic as it silently accepts malformed strings such as "100nsx" or "100us_invalid" by ignoring the trailing characters, leading to potential configuration errors. Introduce a match_time_unit() helper that checks the suffix matches exactly and is followed by either end-of-string or a ':' delimiter. The ':' is needed because parse_ns_duration() is also called from get_long_ns_after_colon() when parsing SCHED_DEADLINE priority specifications in the format "d:runtime:period" (e.g., "d:10ms:100ms"). A plain strcmp() would reject valid deadline strings because the suffix "ms" is followed by ":100ms", not end-of-string. Similarly, strncmp_static() would fail because ARRAY_SIZE() includes the NUL terminator, making it equivalent to strcmp() for this comparison. The match_time_unit() helper solves both problems: it rejects malformed input like "100msx" while correctly handling the colon-delimited deadline format. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260309195040.1019085-13-wander@redhat.com Signed-off-by: Tomas Glozar

rtla: Use str_has_prefix() for prefix checks

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

The code currently uses strncmp() combined with strlen() to check if a string starts with a specific prefix. This pattern is verbose and prone to errors if the length does not match the prefix string. Replace this pattern with the str_has_prefix() helper function in both trace.c and utils.c. This improves code readability and safety by handling the prefix length calculation automatically. In addition, remove the unused retval variable from trace_event_save_hist() in trace.c to clean up the function and silence potential compiler warnings. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260309195040.1019085-12-wander@redhat.com Signed-off-by: Tomas Glozar

rtla: Simplify code by caching string lengths

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

Simplify trace_event_save_hist() and set_comm_cgroup() by computing string lengths once and storing them in local variables, rather than calling strlen() multiple times on the same unchanged strings. This makes the code clearer by eliminating redundant function calls and improving readability. In trace_event_save_hist(), the write loop previously called strlen() on the hist buffer twice per iteration for both the size calculation and loop condition. Store the length in hist_len before entering the loop. In set_comm_cgroup(), strlen() was called on cgroup_path up to three times in succession. Store the result in cg_path_len to use in both the offset calculation and size parameter for subsequent append operations. This simplification makes the code easier to read and maintain without changing program behavior. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260309195040.1019085-7-wander@redhat.com Signed-off-by: Tomas Glozar

rtla: Exit on memory allocation failures during initialization

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

Most memory allocations in rtla happen during early initialization before any resources are acquired that would require cleanup. In these cases, propagating allocation errors just adds complexity without any benefit. There's nothing to clean up, and the program must exit anyway. This patch introduces fatal allocation wrappers (calloc_fatal, reallocarray_fatal, strdup_fatal) that call fatal() on allocation failure. These wrappers simplify the code by eliminating unnecessary error propagation paths. The patch converts early allocations to use these wrappers in actions_init() and related action functions, osnoise_context_alloc() and osnoise_init_tool(), trace_instance_init() and trace event functions, and parameter structure allocations in main functions. This simplifies the code while maintaining the same behavior: immediate exit on allocation failure during initialization. Allocations that require cleanup, such as those in histogram allocation functions with goto cleanup paths, are left unchanged and continue to return errors. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260309195040.1019085-2-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

rtla/timerlat: Add --stack-format option

2026-03-04T14:51:56+00:00

In the current implementation, the auto-analysis code for printing the stack captured in the tracefs buffer of the aa instance stops at the first encountered address that cannot be resolved into a function symbol. This is not always the desired behavior on all platforms; sometimes, there might be resolvable entries after unresolvable ones, and sometimes, the user might want to inspect the raw pointers for the unresolvable entries. Add a new option, --stack-format, with three values: - truncate: stop at first unresolvable entry. This is the current behavior, and is kept as the default. - skip: skip unresolvable entries, but do not stop on them. - full: print all entries, including unresolvable ones. To make this work, the "size" field of the stack entry is now also read and used as the maximum number of entries to print, capped at 64, since that is the fixed length of the "caller" field. Link: https://lore.kernel.org/r/20260119115222.744150-1-tglozar@redhat.com Signed-off-by: Tomas Glozar

rtla: Fix parse_cpu_set() bug introduced by strtoi()

2026-01-13T07:32:52+00:00

The patch 'Replace atoi() with a robust strtoi()' introduced a bug in parse_cpu_set(), which relies on partial parsing of the input string. The function parses CPU specifications like '0-3,5' by incrementing a pointer through the string. strtoi() rejects strings with trailing characters, causing parse_cpu_set() to fail on any CPU list with multiple entries. Restore the original use of atoi() in parse_cpu_set(). Fixes: 7e9dfccf8f11 ("rtla: Replace atoi() with a robust strtoi()") Signed-off-by: Costa Shulyupin Reviewed-by: Masami Hiramatsu (Google) Link: https://lore.kernel.org/r/20260112192642.212848-2-costa.shul@redhat.com Signed-off-by: Tomas Glozar

rtla: Fix parse_cpu_set() return value documentation

2026-01-07T14:57:56+00:00

Correct the return value documentation for parse_cpu_set() function in utils.c. The comment incorrectly stated that the function returns 1 on success and 0 on failure, but the actual implementation returns 0 on success and 1 on failure, following the common error-on-nonzero convention used throughout the codebase. This documentation fix ensures that developers reading the code understand the correct return value semantics and prevents potential misuse of the function's return value in conditional checks. Signed-off-by: Wander Lairson Costa Link: https://lore.kernel.org/r/20260106133655.249887-18-wander@redhat.com Signed-off-by: Tomas Glozar