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-<opt> 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/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
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: dada03db9b ("rtla: Remove procps-ng dependency")
Signed-off-by: Wander Lairson Costa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
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/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
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: 7e9dfccf8f ("rtla: Replace atoi() with a robust strtoi()")
Signed-off-by: Costa Shulyupin <[email protected]>
Reviewed-by: Masami Hiramatsu (Google) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
Add explicit null termination and buffer initialization for read()
operations in procfs_is_workload_pid() and get_self_cgroup() functions.
The read() system call does not null-terminate the data it reads, and
when the buffer is filled to capacity, subsequent string operations
will read past the buffer boundary searching for a null terminator.
In procfs_is_workload_pid(), explicitly set buffer[MAX_PATH-1] to '\0'
to ensure the buffer is always null-terminated before passing it to
strncmp(). In get_self_cgroup(), use memset() to zero the path buffer
before reading, which ensures null termination when retval is less than
MAX_PATH. Additionally, set path[MAX_PATH-1] to '\0' after the read to
handle the case where the buffer is filled completely.
These defensive buffer handling practices prevent potential buffer
overruns and align with the ongoing buffer safety improvements across
the rtla codebase.
Signed-off-by: Wander Lairson Costa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
The atoi() function does not perform error checking, which can lead to
undefined behavior when parsing invalid or out-of-range strings. This
can cause issues when parsing user-provided numerical inputs, such as
signal numbers, PIDs, or CPU lists.
To address this, introduce a new strtoi() helper function that safely
converts a string to an integer. This function validates the input and
checks for overflows, returning a negative value on failure.
Replace all calls to atoi() with the new strtoi() function and add
proper error handling to make the parsing more robust and prevent
potential issues.
Signed-off-by: Wander Lairson Costa <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
Both set_pid_cgroup() and set_comm_cgroup() functions contain
identical code for opening the cgroup.procs file.
Extract this common code into a new helper function open_cgroup_procs()
to reduce code duplication and improve maintainability.
Signed-off-by: Costa Shulyupin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
Currently, user can only specify cgroup to the tracer's thread the
following ways:
`-C[cgroup]`
`-C[=cgroup]`
`--cgroup[=cgroup]`
If user tries to specify cgroup as `-C [cgroup]` or `--cgroup [cgroup]`,
the parser silently fails and rtla's cgroup is used for the tracer
threads.
To make interface more user-friendly, allow user to specify cgroup in
the aforementioned way, i.e. `-C [cgroup]` and `--cgroup [cgroup]`.
Refactor identical logic between -t/--trace and -C/--cgroup into a
common function.
Change documentation to reflect this user interface change.
Fixes: a957cbc025 ("rtla: Add -C cgroup support")
Signed-off-by: Ivan Pravdin <[email protected]>
Reviewed-by: Tomas Glozar <[email protected]>
Link: https://lore.kernel.org/r/16132f1565cf5142b5fbd179975be370b529ced7.1762186418.git.ipravdin.official@gmail.com
[ use capital letter in subject, as required by tracing subsystem ]
Signed-off-by: Tomas Glozar <[email protected]>
The code contains some technical debt in error handling,
which complicates the consolidation of duplicated code.
Introduce an fatal() function to replace the common pattern of
err_msg() followed by exit(EXIT_FAILURE), reducing the length of an
already long function.
Further patches using fatal() follow.
Signed-off-by: Costa Shulyupin <[email protected]>
Reviewed-by: Tomas Glozar <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
When executing "make -C tools/tracing/rtla" on LoongArch, there exists
the following error:
src/utils.c:237:24: error: '__NR_sched_setattr' undeclared
Just define __NR_sched_setattr for LoongArch if not exist.
Link: https://lore.kernel.org/[email protected]
Reported-by: Haiyong Sun <[email protected]>
Signed-off-by: Tiezhu Yang <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
Add functions to utils.c to disable idle states through functions of
libcpupower. This will serve as the basis for disabling idle states
per cpu when running timerlat.
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Tomas Glozar <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
glibc commit 21571ca0d703 ("Linux: Add the sched_setattr
and sched_getattr functions") now also provides 'struct sched_attr'
and sched_setattr() which collide with the ones from rtla.
In file included from src/trace.c:11:
src/utils.h:49:8: error: redefinition of ‘struct sched_attr’
49 | struct sched_attr {
| ^~~~~~~~~~
In file included from /usr/include/bits/sched.h:60,
from /usr/include/sched.h:43,
from /usr/include/tracefs/tracefs.h:10,
from src/trace.c:4:
/usr/include/linux/sched/types.h:98:8: note: originally defined here
98 | struct sched_attr {
| ^~~~~~~~~~
Define 'struct sched_attr' conditionally, similar to what strace did:
https://lore.kernel.org/all/[email protected]/
and rename rtla's version of sched_setattr() to avoid collision.
Link: https://lore.kernel.org/8088f66a7a57c1b209cd8ae0ae7c336a7f8c930d.1728572865.git.jstancek@redhat.com
Signed-off-by: Jan Stancek <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
Variable found is not being initialized, in the case where the desired
mount is not found the variable contains garbage. Fix this by initializing
it to zero.
Link: https://lore.kernel.org/all/[email protected]/
Fixes: a957cbc025 ("rtla: Add -C cgroup support")
Signed-off-by: Colin Ian King <[email protected]>
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Daniel Wagner reported to me that readproc.h got deprecated. Also,
while the procps-ng library was available on Fedora, it was not available
on RHEL, which is a piece of evidence that it was not that used.
rtla uses procps-ng only to find the PID of the tracers' workload.
I used the procps-ng library to avoid reinventing the wheel. But in this
case, reinventing the wheel took me less time than the time we already
took trying to work around problems.
Implement a function that reads /proc/ entries, checking if:
- the entry is a directory
- the directory name is composed only of digits (PID)
- the directory contains the comm file
- the comm file contains a comm that matches the tracers'
workload prefix.
- then return true; otherwise, return false.
And use it instead of procps-ng.
Link: https://lkml.kernel.org/r/e8276e122ee9eb2c5a0ba8e673fb6488b924b825.1652423574.git.bristot@kernel.org
Cc: John Kacur <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Tao Zhou <[email protected]>
Fixes: b1696371d8 ("rtla: Helper functions for rtla")
Reported-by: Daniel Wagner <[email protected]>
Reviewed-by: Daniel Wagner <[email protected]>
Signed-off-by: Daniel Bristot de Oliveira <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
Tomas Glozar