[PATCH v3 2/3] ring-buffer: Handle RB_MISSED_* flags on commit field correctly
STALE222d
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: 2026-02-23 16:16:15
Also in:
lkml
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Since the MSBs of rb_data_page::commit are used for storing
RB_MISSED_EVENTS and RB_MISSED_STORED, we need to mask out those bits
when it is used for finding the size of data pages.
Fixes: 5f3b6e839f3c ("ring-buffer: Validate boot range memory events")
Fixes: 5b7be9c709e1 ("ring-buffer: Add test to validate the time stamp deltas")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Newly added.
---
kernel/trace/ring_buffer.c | 32 ++++++++++++++++----------------
1 file changed, 16 insertions(+), 16 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 84a6459ed494..1ef718d21796 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c@@ -395,6 +395,18 @@ static __always_inline unsigned int rb_page_commit(struct buffer_page *bpage) return local_read(&bpage->page->commit); } +/* Size is determined by what has been committed */ +static __always_inline unsigned rb_page_size(struct buffer_page *bpage) +{ + return rb_page_commit(bpage) & ~RB_MISSED_MASK; +} + +static __always_inline unsigned +rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) +{ + return rb_page_commit(cpu_buffer->commit_page); +} + static void free_buffer_page(struct buffer_page *bpage) { /* Range pages are not to be freed */
@@ -1907,7 +1919,7 @@ static int rb_validate_buffer(struct buffer_data_page *dpage, int cpu) u64 delta; int tail; - tail = local_read(&dpage->commit); + tail = local_read(&dpage->commit) & ~RB_MISSED_MASK; return rb_read_data_buffer(dpage, tail, cpu, &ts, &delta); }
@@ -1934,7 +1946,7 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer) goto invalid; } entries += ret; - entry_bytes += local_read(&cpu_buffer->reader_page->page->commit); + entry_bytes += rb_page_size(cpu_buffer->reader_page); local_set(&cpu_buffer->reader_page->entries, ret); ts = head_page->page->time_stamp;
@@ -2054,7 +2066,7 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer) local_inc(&cpu_buffer->pages_touched); entries += ret; - entry_bytes += local_read(&head_page->page->commit); + entry_bytes += rb_page_size(head_page); local_set(&cpu_buffer->head_page->entries, ret); if (head_page == cpu_buffer->commit_page)
@@ -3257,18 +3269,6 @@ rb_iter_head_event(struct ring_buffer_iter *iter) return NULL; } -/* Size is determined by what has been committed */ -static __always_inline unsigned rb_page_size(struct buffer_page *bpage) -{ - return rb_page_commit(bpage) & ~RB_MISSED_MASK; -} - -static __always_inline unsigned -rb_commit_index(struct ring_buffer_per_cpu *cpu_buffer) -{ - return rb_page_commit(cpu_buffer->commit_page); -} - static __always_inline unsigned rb_event_index(struct ring_buffer_per_cpu *cpu_buffer, struct ring_buffer_event *event) {
@@ -4433,7 +4433,7 @@ static void check_buffer(struct ring_buffer_per_cpu *cpu_buffer, if (tail == CHECK_FULL_PAGE) { full = true; - tail = local_read(&bpage->commit); + tail = local_read(&bpage->commit) & ~RB_MISSED_MASK; } else if (info->add_timestamp & (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE)) { /* Ignore events with absolute time stamps */