From patchwork Thu Oct 13 21:06:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 13006401 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7E69C433FE for ; Thu, 13 Oct 2022 21:11:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229588AbiJMVLG (ORCPT ); Thu, 13 Oct 2022 17:11:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47772 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229696AbiJMVLE (ORCPT ); Thu, 13 Oct 2022 17:11:04 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EB2E92B189; Thu, 13 Oct 2022 14:10:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=tZIWksLvbZf3hKAivkvuzlnH7vev2LNtmjEPqqMctpQ=; b=a5Q74KM2d0akGfotwLs4Oze7xd 5/ohN2Rdfcek3Yqthbqc2LGy9joEXU4R5QpeNAnDlLzf1ha5JAcbRNncDqmQtHb2A80nnOQRND1ey DMV3d3HpEX7Ctu2BWqyjl6J4hy4X/Y1bDZhh4mo22vep7vA27FVULyLrg5NfBoiXKx12Z2IgsBVyH Fdn2HaMiVb9xNaMVxsijAG0HiClg1pGj8EGtrZVckcDsuYYgrT0B8/IuRqvM9g3vk6s3ToCi34RkO lXJ2bFQ/bWJqwMTmM1DGjbLQtQ1IYSKSltQi3nDMmfCPC/acrPq3UyHoenhrQyc7/MVooEIcJzJTN +EaVCKHA==; Received: from 201-43-120-40.dsl.telesp.net.br ([201.43.120.40] helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1oj5Tk-0010yp-8K; Thu, 13 Oct 2022 23:10:57 +0200 From: "Guilherme G. Piccoli" To: linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-efi@vger.kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, keescook@chromium.org, anton@enomsg.org, ccross@android.com, tony.luck@intel.com, ardb@kernel.org, "Guilherme G. Piccoli" Subject: [PATCH V2 1/3] pstore: Alert on backend write error Date: Thu, 13 Oct 2022 18:06:46 -0300 Message-Id: <20221013210648.137452-2-gpiccoli@igalia.com> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221013210648.137452-1-gpiccoli@igalia.com> References: <20221013210648.137452-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org The pstore dump function doesn't alert at all on errors - despite pstore is usually a last resource and if it fails users won't be able to read the kernel log, this is not the case for server users with serial access, for example. So, let's at least attempt to inform such advanced users on the first backend writing error detected during the kmsg dump - this is also very useful for pstore debugging purposes. Signed-off-by: Guilherme G. Piccoli Acked-by: Ard Biesheuvel --- V2: - Show error message late, outside of the critical region (thanks Kees for the idea!). fs/pstore/platform.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c index 06c2c66af332..cbc0b468c1ab 100644 --- a/fs/pstore/platform.c +++ b/fs/pstore/platform.c @@ -393,6 +393,7 @@ static void pstore_dump(struct kmsg_dumper *dumper, const char *why; unsigned int part = 1; unsigned long flags = 0; + int saved_ret = 0; int ret; why = kmsg_dump_reason_str(reason); @@ -463,12 +464,21 @@ static void pstore_dump(struct kmsg_dumper *dumper, if (ret == 0 && reason == KMSG_DUMP_OOPS) { pstore_new_entry = 1; pstore_timer_kick(); + } else { + /* Preserve only the first non-zero returned value. */ + if (!saved_ret) + saved_ret = ret; } total += record.size; part++; } spin_unlock_irqrestore(&psinfo->buf_lock, flags); + + if (saved_ret) { + pr_err_once("backend (%s) writing error (%d)\n", psinfo->name, + saved_ret); + } } static struct kmsg_dumper pstore_dumper = {