On Tue, 12 Dec 2023 13:19:01 -0500 Steven Rostedt <rost...@goodmis.org> wrote:
> From: "Steven Rostedt (Google)" <rost...@goodmis.org> > > Allow a trace write to be as big as the ring buffer tracing data will > allow. Currently, it only allows writes of 1KB in size, but there's no > reason that it cannot allow what the ring buffer can hold. > > Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org> Looks good to me. Reviewed-by: Masami Hiramatsu (Google) <mhira...@kernel.org> Thank you, > --- > Changes since v3: > https://lore.kernel.org/linux-trace-kernel/20231212110332.6fca5...@gandalf.local.home > > - No greated cheese. (Mathieu Desnoyers) > > include/linux/ring_buffer.h | 1 + > kernel/trace/ring_buffer.c | 15 +++++++++++++++ > kernel/trace/trace.c | 31 ++++++++++++++++++++++++------- > 3 files changed, 40 insertions(+), 7 deletions(-) > > diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h > index 782e14f62201..b1b03b2c0f08 100644 > --- a/include/linux/ring_buffer.h > +++ b/include/linux/ring_buffer.h > @@ -141,6 +141,7 @@ int ring_buffer_iter_empty(struct ring_buffer_iter *iter); > bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter); > > unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu); > +unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer); > > void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu); > void ring_buffer_reset_online_cpus(struct trace_buffer *buffer); > diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c > index 6b82c3398938..087f0f6b3409 100644 > --- a/kernel/trace/ring_buffer.c > +++ b/kernel/trace/ring_buffer.c > @@ -5255,6 +5255,21 @@ unsigned long ring_buffer_size(struct trace_buffer > *buffer, int cpu) > } > EXPORT_SYMBOL_GPL(ring_buffer_size); > > +/** > + * ring_buffer_max_event_size - return the max data size of an event > + * @buffer: The ring buffer. > + * > + * Returns the maximum size an event can be. > + */ > +unsigned long ring_buffer_max_event_size(struct trace_buffer *buffer) > +{ > + /* If abs timestamp is requested, events have a timestamp too */ > + if (ring_buffer_time_stamp_abs(buffer)) > + return BUF_MAX_DATA_SIZE - RB_LEN_TIME_EXTEND; > + return BUF_MAX_DATA_SIZE; > +} > +EXPORT_SYMBOL_GPL(ring_buffer_max_event_size); > + > static void rb_clear_buffer_page(struct buffer_page *page) > { > local_set(&page->write, 0); > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index ef86379555e4..a359783fede8 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -7272,8 +7272,9 @@ tracing_mark_write(struct file *filp, const char __user > *ubuf, > enum event_trigger_type tt = ETT_NONE; > struct trace_buffer *buffer; > struct print_entry *entry; > + int meta_size; > ssize_t written; > - int size; > + size_t size; > int len; > > /* Used in tracing_mark_raw_write() as well */ > @@ -7286,12 +7287,12 @@ tracing_mark_write(struct file *filp, const char > __user *ubuf, > if (!(tr->trace_flags & TRACE_ITER_MARKERS)) > return -EINVAL; > > - if (cnt > TRACE_BUF_SIZE) > - cnt = TRACE_BUF_SIZE; > - > - BUILD_BUG_ON(TRACE_BUF_SIZE >= PAGE_SIZE); > + if ((ssize_t)cnt < 0) > + return -EINVAL; > > - size = sizeof(*entry) + cnt + 2; /* add '\0' and possible '\n' */ > + meta_size = sizeof(*entry) + 2; /* add '\0' and possible '\n' */ > + again: > + size = cnt + meta_size; > > /* If less than "<faulted>", then make sure we can still add that */ > if (cnt < FAULTED_SIZE) > @@ -7300,9 +7301,25 @@ tracing_mark_write(struct file *filp, const char > __user *ubuf, > buffer = tr->array_buffer.buffer; > event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, size, > tracing_gen_ctx()); > - if (unlikely(!event)) > + if (unlikely(!event)) { > + /* > + * If the size was greater than what was allowed, then > + * make it smaller and try again. > + */ > + if (size > ring_buffer_max_event_size(buffer)) { > + /* cnt < FAULTED size should never be bigger than max */ > + if (WARN_ON_ONCE(cnt < FAULTED_SIZE)) > + return -EBADF; > + cnt = ring_buffer_max_event_size(buffer) - meta_size; > + /* The above should only happen once */ > + if (WARN_ON_ONCE(cnt + meta_size == size)) > + return -EBADF; > + goto again; > + } > + > /* Ring buffer disabled, return as if not open for write */ > return -EBADF; > + } > > entry = ring_buffer_event_data(event); > entry->ip = _THIS_IP_; > -- > 2.42.0 > -- Masami Hiramatsu (Google) <mhira...@kernel.org>
