From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 95C57FF8875 for ; Tue, 28 Apr 2026 20:21:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=rx2BQAUJ1IxK7gyf+sD2B3OWvxmlQljfsfXOepl3UNQ=; b=XmQB0OJirKXraJQCV6+MQC0gYf y4A6vT7m4sb8BpxwlYfl2Q4D8brcIQp4yg9xuxSuyuQ1Snfhzl6LNMlWPVT7xjWW/2kv0ZiQ6zHmP 4Uqgn67sCMlOnuET0gwjG1GEJEx8xnFS257FLM/nEodOn0Mrh24HWwJMw6aY1dk/xJTJ9ullzAT3y BybjgtlsymRPFfx1RkUd77RRqawu0W72RJpHAl/0Dj5HHCUUbGveRpcyMFfHGKTc61P8qFy3vSp8g bznXTOnQ3XXxz9E2N+krECeScujFx8EokJYiPD4gVj7tvxlFB0HbhN/UhBLbAR5oDY3gdb0b1Sxil KUTX35EQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wHow6-00000002RR9-0BaC; Tue, 28 Apr 2026 20:21:38 +0000 Received: from smtprelay0010.hostedemail.com ([216.40.44.10] helo=relay.hostedemail.com) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wHow4-00000002RQj-10wi for linux-arm-kernel@lists.infradead.org; Tue, 28 Apr 2026 20:21:37 +0000 Received: from omf07.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id E22CE140424; Tue, 28 Apr 2026 20:21:33 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf07.hostedemail.com (Postfix) with ESMTPA id DB11A20032; Tue, 28 Apr 2026 20:21:31 +0000 (UTC) Date: Tue, 28 Apr 2026 16:21:46 -0400 From: Steven Rostedt To: "Masami Hiramatsu (Google)" Cc: Catalin Marinas , Will Deacon , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Ian Rogers , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v18 4/8] ring-buffer: Skip invalid sub-buffers when rewinding persistent ring buffer Message-ID: <20260428162146.78e52988@gandalf.local.home> In-Reply-To: <177701355481.2223789.8929563537404268817.stgit@mhiramat.tok.corp.google.com> References: <177701351903.2223789.17087009302463188638.stgit@mhiramat.tok.corp.google.com> <177701355481.2223789.8929563537404268817.stgit@mhiramat.tok.corp.google.com> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: DB11A20032 X-Stat-Signature: uxqknnieyh6qocc33pm4dz7a11hriibh X-Rspamd-Server: rspamout03 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1+WQB/o4GfEx2nnNkMQzQazvHdAcoOUkS8= X-HE-Tag: 1777407691-181976 X-HE-Meta: U2FsdGVkX1+x9wPUL3Mdg1isPM9pfvR1/hxbPT0fY0XZvtE0Hf2YH9Xd1aKCTwW1VRk5Nzd0AtjHg1RVcGOUNjxGS/QaOBSXB46Rq+uD6AEztUuQVj4UE0TCl5utRe+HA48HVFGRyUKUe2ZO9dLfoOsYirrMSuNqbLarWp1v+31u5nEivCDpiOWwEKlgIONYAGCw0cMS43zASy/EfwX/EFDl+S5VWyNpYs5u9Da9HKa280zLjqQeIDeCHtHlD8Yo/BUiGFydQj0YvUWLBNpiKafYnotbtTc6BoTWRk8kPlzDm9X6qPnmziZlmYv8W1f+Q/cvTtwgRp3Qm+sMcEI/a6SMyjbBQ0U9 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260428_132136_343394_3BEC49FC X-CRM114-Status: GOOD ( 10.55 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 24 Apr 2026 15:52:35 +0900 "Masami Hiramatsu (Google)" 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; > } >