lwn.git/samples/trace_events/trace-events-sample.h, branch v6.9

tracing: Remove second parameter to __assign_rel_str()

2024-03-18T14:33:05+00:00

The second parameter of __assign_rel_str() is no longer used. It can be removed. Note, the only real users of rel_string is user events. This code is just in the sample code for testing purposes. This makes __assign_rel_str() different than __assign_str() but that's fine. __assign_str() is used over 700 places and has a larger impact. That change will come later. Link: https://lore.kernel.org/linux-trace-kernel/20240223162519.2beb8112@gandalf.local.home Cc: Mathieu Desnoyers Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google)

tracing: Add __string_len() example

2024-03-18T14:33:05+00:00

There's no example code that uses __string_len(), and since the sample code is used for testing the event logic, add a use case. Link: https://lore.kernel.org/linux-trace-kernel/20240223152827.5f9f78e2@gandalf.local.home Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Signed-off-by: Steven Rostedt (Google)

tracing: Remove __assign_str_len()

2024-03-18T14:33:05+00:00

Now that __assign_str() gets the length from the __string() (and __string_len()) macros, there's no reason to have a separate __assign_str_len() macro as __assign_str() can get the length of the string needed. Also remove __assign_rel_str() although it had no users anyway. Link: https://lore.kernel.org/linux-trace-kernel/20240223152206.0b650659@gandalf.local.home Cc: Jeff Layton Acked-by: Chuck Lever Signed-off-by: Steven Rostedt (Google)

samples: Replace strlcpy() with strscpy()

2023-11-30T20:20:53+00:00

strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated[1]. Additionally, it returns the size of the source string, not the resulting size of the destination string. In an effort to remove strlcpy() completely[2], replace strlcpy() here with strscpy(). Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1] Link: https://github.com/KSPP/linux/issues/89 [2] Cc: Masami Hiramatsu Cc: Valentin Schneider Cc: "Steven Rostedt (Google)" Cc: Chuck Lever Cc: Geliang Tang Cc: Greg Kroah-Hartman Cc: Christophe JAILLET Cc: Thomas Gleixner Cc: Arnd Bergmann Acked-by: "Steven Rostedt (Google)" Link: https://lore.kernel.org/r/20231116191510.work.550-kees@kernel.org Signed-off-by: Kees Cook

tracing: Fix cpumask() example typo

2022-12-14T16:17:55+00:00

The sample code for using cpumask used the wrong field for the __get_cpumask() helper. It used "cpus" which is the bitmask (but would still give a proper example) instead of the "cpum" that was there to be used. Although it produces the same output, fix it, because it's an example and is confusing in how to properly use the cpumask() macro. Link: https://lore.kernel.org/linux-trace-kernel/20221213221227.56560374@gandalf.local.home Cc: Andrew Morton Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google)

tracing: Add __cpumask to denote a trace event field that is a cpumask_t

2022-11-24T00:08:30+00:00

The trace events have a __bitmask field that can be used for anything that requires bitmasks. Although currently it is only used for CPU masks, it could be used in the future for any type of bitmasks. There is some user space tooling that wants to know if a field is a CPU mask and not just some random unsigned long bitmask. Introduce "__cpumask()" helper functions that work the same as the current __bitmask() helpers but displays in the format file: field:__data_loc cpumask_t *[] mask; offset:36; size:4; signed:0; Instead of: field:__data_loc unsigned long[] mask; offset:32; size:4; signed:0; The main difference is the type. Instead of "unsigned long" it is "cpumask_t *". Note, this type field needs to be a real type in the __dynamic_array() logic that both __cpumask and__bitmask use, but the comparison field requires it to be a scalar type whereas cpumask_t is a structure (non-scalar). But everything works when making it a pointer. Valentin added changes to remove the need of passing in "nr_bits" and the __cpumask will always use nr_cpumask_bits as its size. Link: https://lkml.kernel.org/r/20221014080456.1d32b989@rorschach.local.home Requested-by: Valentin Schneider Reviewed-by: Valentin Schneider Signed-off-by: Valentin Schneider Signed-off-by: Steven Rostedt (Google)

tracing: Add example and documentation for new __vstring() macro

2022-07-24T23:11:17+00:00

Update the sample trace events to include an example that uses the new __vstring() helpers for TRACE_EVENTS. Link: https://lkml.kernel.org/r/20220715175555.16375a3b@gandalf.local.home Signed-off-by: Steven Rostedt (Google)

tracing: Fix mismatched comment in __string_len

2022-01-13T21:23:05+00:00

Here __assign_str_len() should be used for the __string_len type, instead of __assign_str() in the comment. Link: https://lkml.kernel.org/r/5c012db463392d0e6d4f0636203d778962ad060a.1640170494.git.geliang.tang@suse.com Reviewed-by: Masami Hiramatsu Fixes: 883b4aee4dec6 ("tracing: Add trace_event helper macros __string_len() and __assign_str_len()") Signed-off-by: Geliang Tang Signed-off-by: Steven Rostedt

samples/trace_event: Add '__rel_loc' using sample event

2021-12-06T20:37:22+00:00

Add '__rel_loc' using sample event for testing. User can use this for testing purpose. There is no reason to use this macro from the kernel. Link: https://lkml.kernel.org/r/163757343050.510314.2876529802471645178.stgit@devnote2 Cc: Beau Belgrave Cc: Namhyung Kim Cc: Tom Zanussi Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing: Add trace_event helper macros __string_len() and __assign_str_len()

2021-08-17T15:47:52+00:00

There's a few cases that a string that is to be recorded in a trace event, does not have a terminating 'nul' character, and instead, the tracepoint passes in the length of the string to record. Add two helper macros to the trace event code that lets this work easier, than tricks with "%.*s" logic. __string_len() which is similar to __string() for declaration, but takes a length argument. __assign_str_len() which is similar to __assign_str() for assiging the string, but it too takes a length argument. Note, the TRACE_EVENT() macro will allocate the location on the ring buffer to 'len + 1', that will be used to store the string into. It is a requirement that the 'len' used for this is a most the length of the string being recorded. This string can still use __get_str() just like strings created with __string() can use to retrieve the string. Link: https://lore.kernel.org/linux-nfs/20210513105018.7539996a@gandalf.local.home/ Tested-by: Chuck Lever Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Chuck Lever