From: Steven Rostedt <rostedt@kernel.org>
To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Ian Rogers <irogers@google.com>
Subject: [PATCH v20 05/10] ring-buffer: Cleanup persistent ring buffer validation
Date: Wed, 20 May 2026 14:49:43 -0400 [thread overview]
Message-ID: <20260520185017.743458353@kernel.org> (raw)
In-Reply-To: 20260520184938.749337513@kernel.org
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cleanup rb_meta_validate_events() function to make it easier to read.
This includes the following cleanups:
- Introduce rb_validatation_state to hold working variables in
validation.
- Move repleated validation state updates into rb_validate_buffer().
- Move reader_page injection code outside of rb_meta_validate_events().
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/ring_buffer.c | 198 ++++++++++++++++++++-----------------
1 file changed, 107 insertions(+), 91 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 695398d72fbb..3f1dd75ba332 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1883,8 +1883,16 @@ static int rb_read_data_buffer(struct buffer_data_page *dpage, int tail, int cpu
return events;
}
-static int rb_validate_buffer(struct buffer_page *bpage, int cpu,
- struct ring_buffer_cpu_meta *meta, u64 prev_ts, u64 next_ts)
+struct rb_validation_state {
+ unsigned long entries;
+ unsigned long entry_bytes;
+ int discarded;
+ u64 ts;
+};
+
+static int __rb_validate_buffer(struct buffer_page *bpage, int cpu,
+ struct ring_buffer_cpu_meta *meta,
+ u64 prev_ts, u64 next_ts)
{
struct buffer_data_page *dpage = bpage->page;
unsigned long long ts;
@@ -1922,16 +1930,94 @@ static int rb_validate_buffer(struct buffer_page *bpage, int cpu,
return ret;
}
+/**
+ * rb_validate_buffer - validates a single buffer page and updates the state.
+ * @bpage: buffer page to validate
+ * @cpu_buffer: cpu_buffer this page belongs to
+ * @meta: meta of the cpu_buffer
+ * @state: validation state
+ * @prev_ts: previous buffer's timestamp (optional)
+ * @next_ts: next buffer's timestamp (optional)
+ *
+ * If the page is invalid (wrong event length or timestamp), it increments the
+ * discarded counter and warns it. Otherwise, it updates the validation state.
+ */
+static void rb_validate_buffer(struct buffer_page *bpage,
+ struct ring_buffer_per_cpu *cpu_buffer,
+ struct ring_buffer_cpu_meta *meta,
+ struct rb_validation_state *state,
+ u64 prev_ts, u64 next_ts)
+{
+ int ret;
+
+ ret = __rb_validate_buffer(bpage, cpu_buffer->cpu, meta, prev_ts, next_ts);
+ if (ret < 0) {
+ if (!state->discarded)
+ pr_info("Ring buffer meta [%d] invalid buffer page detected\n",
+ cpu_buffer->cpu);
+ state->discarded++;
+ } else {
+ /* If the buffer has content, update pages_touched */
+ if (ret)
+ local_inc(&cpu_buffer->pages_touched);
+
+ state->entries += ret;
+ state->entry_bytes += rb_page_size(bpage);
+ state->ts = bpage->page->time_stamp;
+ }
+}
+
+static void rb_meta_inject_reader_page(struct ring_buffer_per_cpu *cpu_buffer,
+ struct ring_buffer_cpu_meta *meta,
+ struct buffer_page *orig_head,
+ struct buffer_page *head_page)
+{
+ struct buffer_page *bpage = orig_head;
+ int i;
+
+ rb_dec_page(&bpage);
+ /*
+ * Insert the reader_page before the original head page.
+ * Since the list encode RB_PAGE flags, general list
+ * operations should be avoided.
+ */
+ cpu_buffer->reader_page->list.next = &orig_head->list;
+ cpu_buffer->reader_page->list.prev = orig_head->list.prev;
+ orig_head->list.prev = &cpu_buffer->reader_page->list;
+ bpage->list.next = &cpu_buffer->reader_page->list;
+
+ /* Make the head_page the reader page */
+ cpu_buffer->reader_page = head_page;
+ bpage = head_page;
+ rb_inc_page(&head_page);
+ head_page->list.prev = bpage->list.prev;
+ rb_dec_page(&bpage);
+ bpage->list.next = &head_page->list;
+ rb_set_list_to_head(&bpage->list);
+ cpu_buffer->pages = &head_page->list;
+
+ cpu_buffer->head_page = head_page;
+ meta->head_buffer = (unsigned long)head_page->page;
+
+ /* Reset all the indexes */
+ bpage = cpu_buffer->reader_page;
+ meta->buffers[0] = rb_meta_subbuf_idx(meta, bpage->page);
+ bpage->id = 0;
+
+ for (i = 1, bpage = head_page; i < meta->nr_subbufs;
+ i++, rb_inc_page(&bpage)) {
+ meta->buffers[i] = rb_meta_subbuf_idx(meta, bpage->page);
+ bpage->id = i;
+ }
+}
+
/* If the meta data has been validated, now validate the events */
static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
{
struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta;
struct buffer_page *head_page, *orig_head, *orig_reader;
- unsigned long entry_bytes = 0;
- unsigned long entries = 0;
- int discarded = 0;
+ struct rb_validation_state state = { 0 };
int ret;
- u64 ts;
int i;
if (!meta || !meta->head_buffer)
@@ -1941,25 +2027,16 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
orig_reader = cpu_buffer->reader_page;
/* Do the head page first */
- ret = rb_validate_buffer(head_page, cpu_buffer->cpu, meta, 0, 0);
+ ret = __rb_validate_buffer(head_page, cpu_buffer->cpu, meta, 0, 0);
if (ret < 0) {
pr_info("Ring buffer meta [%d] invalid head page detected\n",
cpu_buffer->cpu);
goto skip_rewind;
}
- ts = head_page->page->time_stamp;
+ state.ts = head_page->page->time_stamp;
/* Do the reader page - reader must be previous to head. */
- ret = rb_validate_buffer(orig_reader, cpu_buffer->cpu, meta, 0, ts);
- if (ret < 0) {
- pr_info("Ring buffer meta [%d] invalid reader page detected\n",
- cpu_buffer->cpu);
- discarded++;
- } else {
- entries += ret;
- entry_bytes += rb_page_size(orig_reader);
- ts = orig_reader->page->time_stamp;
- }
+ rb_validate_buffer(orig_reader, cpu_buffer, meta, &state, 0, state.ts);
/*
* Try to rewind the head so that we can read the pages which are already
@@ -1983,19 +2060,7 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
* Skip if the page is invalid, or its timestamp is newer than the
* previous valid page.
*/
- ret = rb_validate_buffer(head_page, cpu_buffer->cpu, meta, 0, ts);
- if (ret < 0) {
- if (!discarded)
- pr_info("Ring buffer meta [%d] invalid buffer page detected\n",
- cpu_buffer->cpu);
- discarded++;
- } else {
- entries += ret;
- entry_bytes += rb_page_size(head_page);
- if (ret > 0)
- local_inc(&cpu_buffer->pages_touched);
- ts = head_page->page->time_stamp;
- }
+ rb_validate_buffer(head_page, cpu_buffer, meta, &state, 0, state.ts);
}
if (i)
pr_info("Ring buffer [%d] rewound %d pages\n", cpu_buffer->cpu, i);
@@ -2009,43 +2074,7 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
* into the location just before the original head page.
*/
if (head_page != orig_head) {
- struct buffer_page *bpage = orig_head;
-
- rb_dec_page(&bpage);
- /*
- * Insert the reader_page before the original head page.
- * Since the list encode RB_PAGE flags, general list
- * operations should be avoided.
- */
- cpu_buffer->reader_page->list.next = &orig_head->list;
- cpu_buffer->reader_page->list.prev = orig_head->list.prev;
- orig_head->list.prev = &cpu_buffer->reader_page->list;
- bpage->list.next = &cpu_buffer->reader_page->list;
-
- /* Make the head_page the reader page */
- cpu_buffer->reader_page = head_page;
- bpage = head_page;
- rb_inc_page(&head_page);
- head_page->list.prev = bpage->list.prev;
- rb_dec_page(&bpage);
- bpage->list.next = &head_page->list;
- rb_set_list_to_head(&bpage->list);
- cpu_buffer->pages = &head_page->list;
-
- cpu_buffer->head_page = head_page;
- meta->head_buffer = (unsigned long)head_page->page;
-
- /* Reset all the indexes */
- bpage = cpu_buffer->reader_page;
- meta->buffers[0] = rb_meta_subbuf_idx(meta, bpage->page);
- bpage->id = 0;
-
- for (i = 1, bpage = head_page; i < meta->nr_subbufs;
- i++, rb_inc_page(&bpage)) {
- meta->buffers[i] = rb_meta_subbuf_idx(meta, bpage->page);
- bpage->id = i;
- }
-
+ rb_meta_inject_reader_page(cpu_buffer, meta, orig_head, head_page);
/* We'll restart verifying from orig_head */
head_page = orig_head;
}
@@ -2057,7 +2086,7 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
/* Nothing more to do, the only page is the reader page */
goto done;
}
- ts = head_page->page->time_stamp;
+ state.ts = head_page->page->time_stamp;
/* Iterate until finding the commit page */
for (i = 0; i < meta->nr_subbufs + 1; i++, rb_inc_page(&head_page)) {
@@ -2066,21 +2095,8 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
if (head_page == orig_reader)
continue;
- ret = rb_validate_buffer(head_page, cpu_buffer->cpu, meta, ts, 0);
- if (ret < 0) {
- if (!discarded)
- pr_info("Ring buffer meta [%d] invalid buffer page detected\n",
- cpu_buffer->cpu);
- discarded++;
- } else {
- /* If the buffer has content, update pages_touched */
- if (ret)
- local_inc(&cpu_buffer->pages_touched);
+ rb_validate_buffer(head_page, cpu_buffer, meta, &state, state.ts, 0);
- entries += ret;
- entry_bytes += rb_page_size(head_page);
- ts = head_page->page->time_stamp;
- }
if (head_page == cpu_buffer->commit_page)
break;
}
@@ -2091,25 +2107,25 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
goto invalid;
}
done:
- local_set(&cpu_buffer->entries, entries);
- local_set(&cpu_buffer->entries_bytes, entry_bytes);
+ local_set(&cpu_buffer->entries, state.entries);
+ local_set(&cpu_buffer->entries_bytes, state.entry_bytes);
pr_info("Ring buffer meta [%d] is from previous boot!", cpu_buffer->cpu);
- if (discarded)
- pr_cont(" (%d pages discarded)", discarded);
+ if (state.discarded)
+ pr_cont(" (%d pages discarded)", state.discarded);
pr_cont("\n");
#ifdef CONFIG_RING_BUFFER_PERSISTENT_INJECT
if (meta->nr_invalid)
pr_warn("Ring buffer testing [%d] invalid pages: %s (%d/%d)\n",
cpu_buffer->cpu,
- (discarded == meta->nr_invalid) ? "PASSED" : "FAILED",
- discarded, meta->nr_invalid);
+ (state.discarded == meta->nr_invalid) ? "PASSED" : "FAILED",
+ state.discarded, meta->nr_invalid);
if (meta->entry_bytes)
pr_warn("Ring buffer testing [%d] entry_bytes: %s (%ld/%ld)\n",
cpu_buffer->cpu,
- (entry_bytes == meta->entry_bytes) ? "PASSED" : "FAILED",
- (long)entry_bytes, (long)meta->entry_bytes);
+ (state.entry_bytes == meta->entry_bytes) ? "PASSED" : "FAILED",
+ (long)state.entry_bytes, (long)meta->entry_bytes);
meta->nr_invalid = 0;
meta->entry_bytes = 0;
#endif
--
2.53.0
next prev parent reply other threads:[~2026-05-20 18:50 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-20 18:49 [PATCH v20 00/10] ring-buffer: Making persistent ring buffers robust Steven Rostedt
2026-05-20 18:49 ` [PATCH v20 01/10] ring-buffer: Skip invalid sub-buffers when validating persistent ring buffer Steven Rostedt
2026-05-20 18:49 ` [PATCH v20 02/10] ring-buffer: Skip invalid sub-buffers when rewinding " Steven Rostedt
2026-05-21 14:17 ` Steven Rostedt
2026-05-20 18:49 ` [PATCH v20 03/10] ring-buffer: Add persistent ring buffer invalid-page inject test Steven Rostedt
2026-05-20 18:49 ` [PATCH v20 04/10] ring-buffer: Show commit numbers in buffer_meta file Steven Rostedt
2026-05-20 18:49 ` Steven Rostedt [this message]
2026-05-20 18:49 ` [PATCH v20 06/10] ring-buffer: Cleanup buffer_data_page related code Steven Rostedt
2026-05-20 18:49 ` [PATCH v20 07/10] ring-buffer: Skip invalid sub-buffers for iterator Steven Rostedt
2026-05-21 2:51 ` Masami Hiramatsu
2026-05-21 2:58 ` Steven Rostedt
2026-05-20 18:49 ` [PATCH v20 08/10] ring-buffer: Have dropped subbuffers be persistent across reboots Steven Rostedt
2026-05-21 6:29 ` Masami Hiramatsu
2026-05-20 18:49 ` [PATCH v20 09/10] ring-buffer: Show persistent buffer dropped events in trace file Steven Rostedt
2026-05-21 6:34 ` Masami Hiramatsu
2026-05-21 12:14 ` Steven Rostedt
2026-05-20 18:49 ` [PATCH v20 10/10] ring-buffer: Show persistent buffer dropped events in trace_pipe file Steven Rostedt
2026-05-21 8:18 ` Masami Hiramatsu
2026-05-21 12:17 ` Steven Rostedt
2026-05-21 8:13 ` [PATCH v20 00/10] ring-buffer: Making persistent ring buffers robust Masami Hiramatsu
2026-05-21 12:17 ` Steven Rostedt
2026-05-21 12:24 ` Steven Rostedt
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