linux-toradex.git/kernel/trace/trace_seq.c, branch v7.0-rc5

tracing: Add bitmask-list option for human-readable bitmask display

2026-01-26T22:00:50+00:00

Add support for displaying bitmasks in human-readable list format (e.g.,
0,2-5,7) in addition to the default hexadecimal bitmap representation.
This is particularly useful when tracing CPU masks and other large
bitmasks where individual bit positions are more meaningful than their
hexadecimal encoding.

When the "bitmask-list" option is enabled, the printk "%*pbl" format
specifier is used to render bitmasks as comma-separated ranges, making
trace output easier to interpret for complex CPU configurations and
large bitmask values.

Link: https://patch.msgid.link/20251226160724.2246493-2-atomlin@atomlin.com
Signed-off-by: Aaron Tomlin 
Signed-off-by: Steven Rostedt (Google)

tracing: Fix typo in trace_seq.c

2025-12-05T20:43:41+00:00

Fix typo "wont" to "won't".

Link: https://patch.msgid.link/20251121221835.28032-15-mhi@mailbox.org
Signed-off-by: Maurice Hieronymus 
Signed-off-by: Steven Rostedt (Google)

trace_seq: Increase the buffer size to almost two pages

2023-12-19T04:14:16+00:00

Now that trace_marker can hold more than 1KB string, and can write as much
as the ring buffer can hold, the trace_seq is not big enough to hold
writes:

 ~# a="1234567890"
 ~# cnt=4080
 ~# s=""
 ~# while [ $cnt -gt 10 ]; do
 ~#	s="${s}${a}"
 ~#	cnt=$((cnt-10))
 ~# done
 ~# echo $s > trace_marker
 ~# cat trace
 # tracer: nop
 #
 # entries-in-buffer/entries-written: 2/2   #P:8
 #
 #                                _-----=> irqs-off/BH-disabled
 #                               / _----=> need-resched
 #                              | / _---=> hardirq/softirq
 #                              || / _--=> preempt-depth
 #                              ||| / _-=> migrate-disable
 #                              |||| /     delay
 #           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
 #              | |         |   |||||     |         |
            <...>-860     [002] .....   105.543465: tracing_mark_write[LINE TOO BIG]
            <...>-860     [002] .....   105.543496: tracing_mark_write: 789012345678901234567890

By increasing the trace_seq buffer to almost two pages, it can now print
out the first line.

This also subtracts the rest of the trace_seq fields from the buffer, so
that the entire trace_seq is now PAGE_SIZE aligned.

Link: https://lore.kernel.org/linux-trace-kernel/20231209175220.19867af4@gandalf.local.home

Cc: Mark Rutland 
Cc: Mathieu Desnoyers 
Reviewed-by: Masami Hiramatsu (Google) 
Signed-off-by: Steven Rostedt (Google)

tracing: Move readpos from seq_buf to trace_seq

2023-10-20T16:16:10+00:00

To make seq_buf more lightweight as a string buf, move the readpos member
from seq_buf to its container, trace_seq.  That puts the responsibility
of maintaining the readpos entirely in the tracing code.  If some future
users want to package up the readpos with a seq_buf, we can define a
new struct then.

Link: https://lore.kernel.org/linux-trace-kernel/20231020033545.2587554-2-willy@infradead.org

Cc: Kees Cook 
Cc: Justin Stitt 
Cc: Kent Overstreet 
Cc: Petr Mladek 
Cc: Andy Shevchenko 
Cc: Rasmus Villemoes 
Cc: Sergey Senozhatsky 
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Christoph Hellwig 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Steven Rostedt (Google)

tracing: Fix kernel-doc warnings in trace_seq.c

2023-07-28T23:59:04+00:00

Fix kernel-doc warning:

kernel/trace/trace_seq.c:142: warning: Function parameter or member
'args' not described in 'trace_seq_vprintf'

Link: https://lkml.kernel.org/r/20230724140827.1023266-5-cuigaosheng1@huawei.com

Cc: 
Signed-off-by: Gaosheng Cui 
Signed-off-by: Steven Rostedt (Google)

tracing: Acquire buffer from temparary trace sequence

2023-02-07T17:42:54+00:00

there is one dwc3 trace event declare as below,
DECLARE_EVENT_CLASS(dwc3_log_event,
	TP_PROTO(u32 event, struct dwc3 *dwc),
	TP_ARGS(event, dwc),
	TP_STRUCT__entry(
		__field(u32, event)
		__field(u32, ep0state)
		__dynamic_array(char, str, DWC3_MSG_MAX)
	),
	TP_fast_assign(
		__entry->event = event;
		__entry->ep0state = dwc->ep0state;
	),
	TP_printk("event (%08x): %s", __entry->event,
			dwc3_decode_event(__get_str(str), DWC3_MSG_MAX,
				__entry->event, __entry->ep0state))
);
the problem is when trace function called, it will allocate up to
DWC3_MSG_MAX bytes from trace event buffer, but never fill the buffer
during fast assignment, it only fill the buffer when output function are
called, so this means if output function are not called, the buffer will
never used.

add __get_buf(len) which acquiree buffer from iter->tmp_seq when trace
output function called, it allow user write string to acquired buffer.

the mentioned dwc3 trace event will changed as below,
DECLARE_EVENT_CLASS(dwc3_log_event,
	TP_PROTO(u32 event, struct dwc3 *dwc),
	TP_ARGS(event, dwc),
	TP_STRUCT__entry(
		__field(u32, event)
		__field(u32, ep0state)
	),
	TP_fast_assign(
		__entry->event = event;
		__entry->ep0state = dwc->ep0state;
	),
	TP_printk("event (%08x): %s", __entry->event,
		dwc3_decode_event(__get_buf(DWC3_MSG_MAX), DWC3_MSG_MAX,
				__entry->event, __entry->ep0state))
);.

Link: https://lore.kernel.org/linux-trace-kernel/1675065249-23368-1-git-send-email-quic_linyyuan@quicinc.com

Cc: Masami Hiramatsu 
Signed-off-by: Linyu Yuan 
Signed-off-by: Steven Rostedt (Google)

tracing: Fix various typos in comments

2021-03-23T18:08:18+00:00

Fix ~59 single-word typos in the tracing code comments, and fix
the grammar in a handful of places.

Link: https://lore.kernel.org/r/20210322224546.GA1981273@gmail.com
Link: https://lkml.kernel.org/r/20210323174935.GA4176821@gmail.com

Reviewed-by: Randy Dunlap 
Signed-off-by: Ingo Molnar 
Signed-off-by: Steven Rostedt (VMware)

tracing: Remove unused TRACE_SEQ_BUF_USED

2020-01-21T23:39:54+00:00

This macro isn't used from commit 3a161d99c43c ("tracing: Create
seq_buf layer in trace_seq"). so no needs to keep it.

Link: http://lkml.kernel.org/r/1579586086-45543-1-git-send-email-alex.shi@linux.alibaba.com

Signed-off-by: Alex Shi 
Signed-off-by: Steven Rostedt (VMware)

tracing: Fix indentation issue

2020-01-03T20:20:46+00:00

There is a declaration that is indented one level too deeply, remove
the extraneous tab.

Link: http://lkml.kernel.org/r/20191221154825.33073-1-colin.king@canonical.com

Signed-off-by: Colin Ian King 
Signed-off-by: Steven Rostedt (VMware)

tracing: Use seq_buf_hex_dump() to dump buffers

2019-11-14T18:15:12+00:00

Without this, buffers can be printed with __print_array macro that has
no formatting options and can be hard to read. The other way is to
mimic formatting capability with multiple calls of trace event with one
call per row which gives performance impact and different timestamp in
each row.

Link: http://lkml.kernel.org/r/1573130738-29390-2-git-send-email-piotrx.maziarz@linux.intel.com

Signed-off-by: Piotr Maziarz 
Signed-off-by: Cezary Rojewski 
Signed-off-by: Steven Rostedt (VMware)