[for-next][PATCH 05/11] tracing: Move buffer in trace_seq to end of struct

From: Steven Rostedt

Date: Tue Sep 30 2025 - 13:01:26 EST


From: Elijah Wright <git@elijahs.space>

TRACE_SEQ_BUFFER_SIZE is dependent on the architecture for its size. on 64-bit
systems, it is 8148 bytes. forced 8-byte alignment in size_t and seq_buf means
that trace_seq is 8200 bytes on 64-bit systems. moving the buffer to the end
of the struct fixes the issue. there shouldn't be any side effects, i.e.
pointer arithmetic on trace_seq

Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Link: https://lore.kernel.org/20250821053917.23301-1-git@elijahs.space
Signed-off-by: Elijah Wright <git@elijahs.space>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
include/linux/trace_seq.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index a93ed5ac3226..557780fe1c77 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -21,10 +21,10 @@
(sizeof(struct seq_buf) + sizeof(size_t) + sizeof(int)))

struct trace_seq {
- char buffer[TRACE_SEQ_BUFFER_SIZE];
struct seq_buf seq;
size_t readpos;
int full;
+ char buffer[TRACE_SEQ_BUFFER_SIZE];
};

static inline void
--
2.50.1