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 X-Spam-Level: X-Spam-Status: No, score=-9.3 required=3.0 tests=BAYES_00, BUG6152_INVALID_DATE_TZ_ABSURD,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,INVALID_DATE_TZ_ABSURD, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E90A1C43461 for ; Tue, 8 Sep 2020 20:29:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A4E652080A for ; Tue, 8 Sep 2020 20:29:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="YLy1dUAj"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Sf6t5Ggw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730150AbgIHU3K (ORCPT ); Tue, 8 Sep 2020 16:29:10 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:56846 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728184AbgIHU3E (ORCPT ); Tue, 8 Sep 2020 16:29:04 -0400 From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1599596941; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OmfOJhJGeZam4W8hd+NxCaKhrjMMSs2RZWBSk5gH5+I=; b=YLy1dUAjrkO7qcxtibLWTsQn0THy1435mJlqzfhtCgUj94GiRS0q0rcUwsrBPJgZKXdgux F6Qzc+1Dy8Ke7faRlBFUGi4A1A9I3j8wUdMj0GIwcQIHmVd+AceEdnLgjdkOV8cODxmeVR +U//YQAgsYK2s3vVP4EInRgsZkp+NyGz2jDNFoen4PYpv5dwdCQSTIKBnyTQzR2UtNC4KB EyDlT9p0/G7BR76KFj3kI2JkTjKjArquH3C80jkShInVbyEkluwhqhnGlYe9hHJDKt2T1B Di82LPIe4gRP9fFACmOcm92DruKt+w/GYRVVanGNQJGNzK+6YPFQA238tot8yg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1599596941; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OmfOJhJGeZam4W8hd+NxCaKhrjMMSs2RZWBSk5gH5+I=; b=Sf6t5Ggw80z8llsGefDmljc5f0W/4ewUz4qTH4Z/qdzy+WryDwpmBI92vcPcqX70qlsULk S6l4hiOjJmP6e9AA== To: Petr Mladek Cc: Sergey Senozhatsky , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Thomas Gleixner , Peter Zijlstra , Andrea Parri , Paul McKenney , kexec@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH printk v4 3/6] printk: ringbuffer: clear initial reserved fields Date: Tue, 8 Sep 2020 22:34:56 +0206 Message-Id: <20200908202859.2736-4-john.ogness@linutronix.de> In-Reply-To: <20200908202859.2736-1-john.ogness@linutronix.de> References: <20200908202859.2736-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org prb_reserve() will set some meta data values and leave others uninitialized (or rather, containing the values of the previous wrap). Simplify the API by always clearing out all the fields. Only the sequence number is filled in. The caller is now responsible for filling in the rest of the meta data fields. In particular, for correctly filling in text and dict lengths. Signed-off-by: John Ogness --- kernel/printk/printk.c | 12 ++++++++---- kernel/printk/printk_ringbuffer.c | 30 ++++++++++++++++++------------ 2 files changed, 26 insertions(+), 16 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index fec71229169e..964b5701688f 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -520,8 +520,11 @@ static int log_store(u32 caller_id, int facility, int level, memcpy(&r.text_buf[0], text, text_len); if (trunc_msg_len) memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len); - if (r.dict_buf) + r.info->text_len = text_len + trunc_msg_len; + if (r.dict_buf) { memcpy(&r.dict_buf[0], dict, dict_len); + r.info->dict_len = dict_len; + } r.info->facility = facility; r.info->level = level & 7; r.info->flags = flags & 0x1f; @@ -1069,10 +1072,11 @@ static unsigned int __init add_to_rb(struct printk_ringbuffer *rb, if (!prb_reserve(&e, rb, &dest_r)) return 0; - memcpy(&dest_r.text_buf[0], &r->text_buf[0], dest_r.text_buf_size); + memcpy(&dest_r.text_buf[0], &r->text_buf[0], r->info->text_len); + dest_r.info->text_len = r->info->text_len; if (dest_r.dict_buf) { - memcpy(&dest_r.dict_buf[0], &r->dict_buf[0], - dest_r.dict_buf_size); + memcpy(&dest_r.dict_buf[0], &r->dict_buf[0], r->info->dict_len); + dest_r.info->dict_len = r->info->dict_len; } dest_r.info->facility = r->info->facility; dest_r.info->level = r->info->level; diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c index 6ee5ebce1450..82347abb22a5 100644 --- a/kernel/printk/printk_ringbuffer.c +++ b/kernel/printk/printk_ringbuffer.c @@ -146,10 +146,13 @@ * * if (prb_reserve(&e, &test_rb, &r)) { * snprintf(r.text_buf, r.text_buf_size, "%s", textstr); + * r.info->text_len = strlen(textstr); * * // dictionary allocation may have failed - * if (r.dict_buf) + * if (r.dict_buf) { * snprintf(r.dict_buf, r.dict_buf_size, "%s", dictstr); + * r.info->dict_len = strlen(dictstr); + * } * * r.info->ts_nsec = local_clock(); * @@ -1125,9 +1128,9 @@ static const char *get_data(struct prb_data_ring *data_ring, * @dict_buf_size is set to 0. Writers must check this before writing to * dictionary space. * - * @info->text_len and @info->dict_len will already be set to @text_buf_size - * and @dict_buf_size, respectively. If dictionary space reservation fails, - * @info->dict_len is set to 0. + * Important: @info->text_len and @info->dict_len need to be set correctly by + * the writer in order for data to be readable and/or extended. + * Their values are initialized to 0. */ bool prb_reserve(struct prb_reserved_entry *e, struct printk_ringbuffer *rb, struct printk_record *r) @@ -1135,6 +1138,7 @@ bool prb_reserve(struct prb_reserved_entry *e, struct printk_ringbuffer *rb, struct prb_desc_ring *desc_ring = &rb->desc_ring; struct prb_desc *d; unsigned long id; + u64 seq; if (!data_check_size(&rb->text_data_ring, r->text_buf_size)) goto fail; @@ -1159,6 +1163,14 @@ bool prb_reserve(struct prb_reserved_entry *e, struct printk_ringbuffer *rb, d = to_desc(desc_ring, id); + /* + * All @info fields (except @seq) are cleared and must be filled in + * by the writer. Save @seq before clearing because it is used to + * determine the new sequence number. + */ + seq = d->info.seq; + memset(&d->info, 0, sizeof(d->info)); + /* * Set the @e fields here so that prb_commit() can be used if * text data allocation fails. @@ -1177,17 +1189,15 @@ bool prb_reserve(struct prb_reserved_entry *e, struct printk_ringbuffer *rb, * See the "Bootstrap" comment block in printk_ringbuffer.h for * details about how the initializer bootstraps the descriptors. */ - if (d->info.seq == 0 && DESC_INDEX(desc_ring, id) != 0) + if (seq == 0 && DESC_INDEX(desc_ring, id) != 0) d->info.seq = DESC_INDEX(desc_ring, id); else - d->info.seq += DESCS_COUNT(desc_ring); + d->info.seq = seq + DESCS_COUNT(desc_ring); r->text_buf = data_alloc(rb, &rb->text_data_ring, r->text_buf_size, &d->text_blk_lpos, id); /* If text data allocation fails, a data-less record is committed. */ if (r->text_buf_size && !r->text_buf) { - d->info.text_len = 0; - d->info.dict_len = 0; prb_commit(e); /* prb_commit() re-enabled interrupts. */ goto fail; @@ -1204,10 +1214,6 @@ bool prb_reserve(struct prb_reserved_entry *e, struct printk_ringbuffer *rb, r->info = &d->info; - /* Set default values for the sizes. */ - d->info.text_len = r->text_buf_size; - d->info.dict_len = r->dict_buf_size; - /* Record full text space used by record. */ e->text_space = space_used(&rb->text_data_ring, &d->text_blk_lpos); -- 2.20.1