From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 788C03783AC; Wed, 29 Apr 2026 15:20:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777476026; cv=none; b=lzfNfYoj37AVdZql6RX7XyW0KmGoQk+zq3weFd+9Mchc2mSGv9ScKM7aG2hWRLbJCEtox+dv7I6DpdNcwsWKKFM2F/b9xz0CrqjXJgdfZX+/OUTIfeTO0wj/fXRxNQ2mCwxwbcOwnyOtAoXvy8F8jyNPdY1Cz5Q1hxlKVBBnPTY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777476026; c=relaxed/simple; bh=iRtJTYnWWpEWI9sc96kjWYUWN9eoqli1GDs2kMFzcbc=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=eDB1esrG6Bs+GcRuxmcf6qe/Fv0h8BDG/Q2o/iUhJphjiu788ms+XLsC68oUTKb2RFhjyB6sI7n9xduk7I5yKkMNJiD3j6ivkmcvHWFNiahVraLJnIpA9RenuviGo5+2BjFoDTGhbAvdfqTOrzDkYtlmZIkrLS0epdDg5nyxSoI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rgAD3s71; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rgAD3s71" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E936EC19425; Wed, 29 Apr 2026 15:20:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777476026; bh=iRtJTYnWWpEWI9sc96kjWYUWN9eoqli1GDs2kMFzcbc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=rgAD3s71Iddnt7NVEUWoeX/uhntmqnmf4ij+Qu3t33coW2DmX02hlUzxvH6DyJv10 EzYK42UFDXvu2e7D3zctYWpNYESrwLhCu8taPjw0ME6bZRwWr+shtPqYms2PvOqCQd HeNbWUyxoSQVbuvUSZl7uK0zRAAC0dNJzcijN75qkBhMVY9SIUOWZOVCe31lbc4oSe bNBj8eTuWwsyw7JHPxCwzZyRkMeHVmkSjcwtNEHMuL53hhha2Mlgaw1WliJs9C/k1H iohsJ2NUQFLoKRhMRJu5MEYSa0PWfScpwYNiY6N70DfzdrHEMKQDhUnuZTa4dDJdN1 io0+WuMwNWKIA== Date: Thu, 30 Apr 2026 00:20:23 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt 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: <20260430002023.b19608c27a746284e8f73b80@kernel.org> In-Reply-To: <20260428162146.78e52988@gandalf.local.home> References: <177701351903.2223789.17087009302463188638.stgit@mhiramat.tok.corp.google.com> <177701355481.2223789.8929563537404268817.stgit@mhiramat.tok.corp.google.com> <20260428162146.78e52988@gandalf.local.home> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 28 Apr 2026 16:21:46 -0400 Steven Rostedt wrote: > 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. OK, I'll add it, or let code explain clearer? if (tail <= meta->subbuf_size - BUF_PAGE_HDR_SIZE) ret = rb_read_data_buffer(dpage, tail, cpu, &ts, &delta); else ret = -1; Thanks, > > -- 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; > > } > > -- Masami Hiramatsu (Google)