On Tue, 23 Jun 2026 21:51:47 +0700 Woradorn Laodhanadhaworn <[email protected]> wrote:
> In preparation for removing the strlcat API[1], > replace the string concatenation logic with a struct seq_buf, > which tracks the current position and the remaining space internally. > > Use seq_buf_str() to NUL-terminate before passing to early_enable_events(). > > Link: https://github.com/KSPP/linux/issues/370 [1] > Looks good to me. Acked-by: Masami Hiramatsu (Google) <[email protected]> Thanks, > Signed-off-by: Woradorn Laodhanadhaworn <[email protected]> > --- > v1 -> v2: > - Fixed WARN_ON when booting with empty trace_event. > v2 -> v3: > - Addressed Sashiko's concern about the compound literal backing buffer. > - Replaced the compund literal with an explicit declared buffer and > pointed > seq_buf.buffer to it. This guarantees the backing storage is placed in > `.init.data` and reclaimed after boot. > > v1: > https://lore.kernel.org/all/[email protected] > v2: https://lore.kernel.org/all/[email protected] > Sashiko: > https://sashiko.dev/#/patchset/20260622094623.18469-1-woradorn.laon%40gmail.com > > kernel/trace/trace_events.c | 18 +++++++++++++----- > 1 file changed, 13 insertions(+), 5 deletions(-) > > diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c > index c46e623e7e0d..5ab630155ab6 100644 > --- a/kernel/trace/trace_events.c > +++ b/kernel/trace/trace_events.c > @@ -22,6 +22,7 @@ > #include <linux/sort.h> > #include <linux/slab.h> > #include <linux/delay.h> > +#include <linux/seq_buf.h> > > #include <trace/events/sched.h> > #include <trace/syscall.h> > @@ -4501,13 +4502,20 @@ extern struct trace_event_call > *__start_ftrace_events[]; > extern struct trace_event_call *__stop_ftrace_events[]; > > static char bootup_event_buf[COMMAND_LINE_SIZE] __initdata; > +static struct seq_buf bootup_event_seq __initdata = { > + .buffer = bootup_event_buf, > + .size = COMMAND_LINE_SIZE, > +}; > > static __init int setup_trace_event(char *str) > { > - if (bootup_event_buf[0] != '\0') > - strlcat(bootup_event_buf, ",", COMMAND_LINE_SIZE); > + if (seq_buf_used(&bootup_event_seq) > 0) > + seq_buf_puts(&bootup_event_seq, ","); > + > + seq_buf_puts(&bootup_event_seq, str); > > - strlcat(bootup_event_buf, str, COMMAND_LINE_SIZE); > + if (seq_buf_has_overflowed(&bootup_event_seq)) > + return -ENOMEM; > > trace_set_ring_buffer_expanded(NULL); > disable_tracing_selftest("running event tracing"); > @@ -4766,7 +4774,7 @@ static __init int event_trace_enable(void) > */ > __trace_early_add_events(tr); > > - early_enable_events(tr, bootup_event_buf, false); > + early_enable_events(tr, (char *)seq_buf_str(&bootup_event_seq), false); > > trace_printk_start_comm(); > > @@ -4794,7 +4802,7 @@ static __init int event_trace_enable_again(void) > if (!tr) > return -ENODEV; > > - early_enable_events(tr, bootup_event_buf, true); > + early_enable_events(tr, (char *)seq_buf_str(&bootup_event_seq), true); > > return 0; > } > -- > 2.43.0 > -- Masami Hiramatsu (Google) <[email protected]>
