diff options
| author | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-03-04 19:13:42 -0500 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-03-06 13:27:00 -0500 |
| commit | 6f42249fecb94dfb6514ed241475f748c03d62fb (patch) | |
| tree | d112fcb0830155a203ba7e5bed61d6cd7bb720f9 | |
| parent | 5efd3e2aef91d2d812290dcb25b2058e6f3f532c (diff) | |
tracing: Limit trace_seq size to just 8K and not depend on architecture PAGE_SIZE
The trace_seq buffer is used to print out entire events. It's typically
set to PAGE_SIZE * 2 as there's some events that can be quite large.
As a side effect, writes to trace_marker is limited by both the size of the
trace_seq buffer as well as the ring buffer's sub-buffer size (which is a
power of PAGE_SIZE). By limiting the trace_seq size, it also limits the
size of the largest string written to trace_marker.
trace_seq does not need to be dependent on PAGE_SIZE like the ring buffer
sub-buffers need to be. Hard code it to 8K which is PAGE_SIZE * 2 on most
architectures. This will also limit the size of trace_marker on those
architectures with greater than 4K PAGE_SIZE.
Link: https://lore.kernel.org/all/20240302111244.3a1674be@gandalf.local.home/
Link: https://lore.kernel.org/linux-trace-kernel/20240304191342.56fb1087@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sachin Sant <sachinp@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
| -rw-r--r-- | include/linux/trace_seq.h | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h index 9ec229dfddaa..1ef95c0287f0 100644 --- a/include/linux/trace_seq.h +++ b/include/linux/trace_seq.h @@ -9,9 +9,15 @@ /* * Trace sequences are used to allow a function to call several other functions * to create a string of data to use. + * + * Have the trace seq to be 8K which is typically PAGE_SIZE * 2 on + * most architectures. The TRACE_SEQ_BUFFER_SIZE (which is + * TRACE_SEQ_SIZE minus the other fields of trace_seq), is the + * max size the output of a trace event may be. */ -#define TRACE_SEQ_BUFFER_SIZE (PAGE_SIZE * 2 - \ +#define TRACE_SEQ_SIZE 8192 +#define TRACE_SEQ_BUFFER_SIZE (TRACE_SEQ_SIZE - \ (sizeof(struct seq_buf) + sizeof(size_t) + sizeof(int))) struct trace_seq { |