From: Steven Rostedt (Google) Date: Tue, 5 Mar 2024 00:13:42 +0000 (-0500) Subject: tracing: Limit trace_seq size to just 8K and not depend on architecture PAGE_SIZE X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=6f42249fecb94dfb6514ed241475f748c03d62fb;p=linux.git 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 Cc: Mathieu Desnoyers Cc: Linus Torvalds Cc: Sachin Sant Signed-off-by: Steven Rostedt (Google) --- diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h index 9ec229dfddaa7..1ef95c0287f05 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 {