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ring-buffer: Do not double count the reader_page

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Since the cpu_buffer->reader_page is updated if there are unwound
pages. After that update, we should skip the page if it is the
original reader_page, because the original reader_page is already
checked.

Cc: stable@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ian Rogers <irogers@google.com>
Link: https://patch.msgid.link/177701353063.2223789.1471163147644103306.stgit@mhiramat.tok.corp.google.com
Fixes: ca296d32ec ("tracing: ring_buffer: Rewind persistent ring buffer on reboot")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Masami Hiramatsu (Google)
2026-04-24 15:52:10 +09:00
committed by Steven Rostedt
parent 5335e318ad
commit 92d5a60672
1 changed files with 7 additions and 6 deletions
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13
kernel/trace/ring_buffer.c
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@@ -1884,7 +1884,7 @@ static int rb_validate_buffer(struct buffer_data_page *dpage, int cpu)
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;
struct buffer_page *head_page, *orig_head, *orig_reader;
unsigned long entry_bytes = 0;
unsigned long entries = 0;
int ret;
@@ -1895,16 +1895,17 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
return;
orig_head = head_page = cpu_buffer->head_page;
orig_reader = cpu_buffer->reader_page;
/* Do the reader page first */
ret = rb_validate_buffer(cpu_buffer->reader_page->page, cpu_buffer->cpu);
ret = rb_validate_buffer(orig_reader->page, cpu_buffer->cpu);
if (ret < 0) {
pr_info("Ring buffer reader page is invalid\n");
goto invalid;
}
entries += ret;
entry_bytes += local_read(&cpu_buffer->reader_page->page->commit);
local_set(&cpu_buffer->reader_page->entries, ret);
entry_bytes += local_read(&orig_reader->page->commit);
local_set(&orig_reader->entries, ret);
ts = head_page->page->time_stamp;
@@ -2007,8 +2008,8 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
/* Iterate until finding the commit page */
for (i = 0; i < meta->nr_subbufs + 1; i++, rb_inc_page(&head_page)) {
/* Reader page has already been done */
if (head_page == cpu_buffer->reader_page)
/* The original reader page has already been checked/counted. */
if (head_page == orig_reader)
continue;
ret = rb_validate_buffer(head_page->page, cpu_buffer->cpu);