From: Steven Rostedt <rostedt@goodmis.org>
To: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
Ian Rogers <irogers@google.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v18 4/8] ring-buffer: Skip invalid sub-buffers when rewinding persistent ring buffer
Date: Tue, 28 Apr 2026 16:21:46 -0400 [thread overview]
Message-ID: <20260428162146.78e52988@gandalf.local.home> (raw)
In-Reply-To: <177701355481.2223789.8929563537404268817.stgit@mhiramat.tok.corp.google.com>
On Fri, 24 Apr 2026 15:52:35 +0900
"Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:
> @@ -1892,9 +1895,19 @@ static int rb_validate_buffer(struct buffer_data_page *dpage, int cpu,
> * subbuf_size is considered invalid.
> */
> tail = local_read(&dpage->commit) & ~RB_MISSED_MASK;
> - if (tail > meta->subbuf_size - BUF_PAGE_HDR_SIZE)
> - return -1;
> - return rb_read_data_buffer(dpage, tail, cpu, &ts, &delta);
> + if (tail <= meta->subbuf_size - BUF_PAGE_HDR_SIZE)
> + ret = rb_read_data_buffer(dpage, tail, cpu, &ts, &delta);
> +
This code seriously needs comments.
-- Steve
> + if (ret < 0 || (prev_ts && prev_ts > ts) || (next_ts && ts > next_ts)) {
> + local_set(&bpage->entries, 0);
> + local_set(&bpage->page->commit, 0);
> + bpage->page->time_stamp = prev_ts ? prev_ts : next_ts;
> + ret = -1;
> + } else {
> + local_set(&bpage->entries, ret);
> + }
> +
> + return ret;
> }
>
next prev parent reply other threads:[~2026-04-28 20:21 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-24 6:51 [PATCH v18 0/8] ring-buffer: Making persistent ring buffers robust Masami Hiramatsu (Google)
2026-04-24 6:52 ` [PATCH v18 1/8] ring-buffer: Do not double count the reader_page Masami Hiramatsu (Google)
2026-04-24 6:52 ` [PATCH v18 2/8] ring-buffer: Flush and stop persistent ring buffer on panic Masami Hiramatsu (Google)
2026-04-24 6:52 ` [PATCH v18 3/8] ring-buffer: Skip invalid sub-buffers when validating persistent ring buffer Masami Hiramatsu (Google)
2026-04-28 19:55 ` Steven Rostedt
2026-04-29 15:15 ` Masami Hiramatsu
2026-04-29 16:32 ` Steven Rostedt
2026-04-24 6:52 ` [PATCH v18 4/8] ring-buffer: Skip invalid sub-buffers when rewinding " Masami Hiramatsu (Google)
2026-04-28 20:21 ` Steven Rostedt [this message]
2026-04-29 15:20 ` Masami Hiramatsu
2026-04-29 16:39 ` Steven Rostedt
2026-04-24 6:52 ` [PATCH v18 5/8] ring-buffer: Add persistent ring buffer invalid-page inject test Masami Hiramatsu (Google)
2026-04-24 6:52 ` [PATCH v18 6/8] ring-buffer: Show commit numbers in buffer_meta file Masami Hiramatsu (Google)
2026-04-24 6:52 ` [PATCH v18 7/8] ring-buffer: Cleanup persistent ring buffer validation Masami Hiramatsu (Google)
2026-04-28 20:24 ` Steven Rostedt
2026-04-29 15:21 ` Masami Hiramatsu
2026-04-29 15:50 ` Steven Rostedt
2026-04-24 6:53 ` [PATCH v18 8/8] ring-buffer: Cleanup buffer_data_page related code Masami Hiramatsu (Google)
2026-04-24 7:06 ` [PATCH v18 0/8] ring-buffer: Making persistent ring buffers robust Masami Hiramatsu
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