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Message-ID: <202301052114.vvN3wQoH-lkp@intel.com>
Date: Thu, 5 Jan 2023 21:14:03 +0800
From: kernel test robot <lkp@...el.com>
To: John Ogness <john.ogness@...utronix.de>,
Petr Mladek <pmladek@...e.com>
Cc: oe-kbuild-all@...ts.linux.dev,
Sergey Senozhatsky <senozhatsky@...omium.org>,
Steven Rostedt <rostedt@...dmis.org>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH printk v3 6/6] printk: introduce
console_prepend_dropped() for dropped messages
Hi John,
I love your patch! Perhaps something to improve:
[auto build test WARNING on 6b2b0d839acaa84f05a77184370f793752e786e9]
url: https://github.com/intel-lab-lkp/linux/commits/John-Ogness/printk-cleanup-buffer-handling/20221222-044216
base: 6b2b0d839acaa84f05a77184370f793752e786e9
patch link: https://lore.kernel.org/r/20221221202704.857925-7-john.ogness%40linutronix.de
patch subject: [PATCH printk v3 6/6] printk: introduce console_prepend_dropped() for dropped messages
config: loongarch-randconfig-m031-20230103
compiler: loongarch64-linux-gcc (GCC) 12.1.0
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>
smatch warnings:
kernel/printk/printk.c:2735 console_prepend_dropped() warn: always true condition '(cmsg->outbuf_len + len >= outbuf_sz) => (0-u64max >= 0)'
vim +2735 kernel/printk/printk.c
2701
2702 /*
2703 * Prepend the message in @cmsg->cbufs->outbuf with a "dropped message". This
2704 * is achieved by shifting the existing message over and inserting the dropped
2705 * message.
2706 *
2707 * @cmsg is the console message to prepend.
2708 *
2709 * @dropped is the dropped count to report in the dropped message.
2710 *
2711 * If the message text in @cmsg->cbufs->outbuf does not have enough space for
2712 * the dropped message, the message text will be sufficiently truncated.
2713 *
2714 * If @cmsg->cbufs->outbuf is modified, @cmsg->outbuf_len is updated.
2715 */
2716 static void console_prepend_dropped(struct console_message *cmsg, unsigned long dropped)
2717 {
2718 struct console_buffers *cbufs = cmsg->cbufs;
2719 const size_t scratchbuf_sz = sizeof(cbufs->scratchbuf);
2720 const size_t outbuf_sz = sizeof(cbufs->outbuf);
2721 char *scratchbuf = &cbufs->scratchbuf[0];
2722 char *outbuf = &cbufs->outbuf[0];
2723 size_t len;
2724
2725 len = snprintf(scratchbuf, scratchbuf_sz,
2726 "** %lu printk messages dropped **\n", dropped);
2727
2728 /*
2729 * Make sure outbuf is sufficiently large before prepending. Space
2730 * for a terminator is also counted in case truncation occurs.
2731 */
2732 if (WARN_ON_ONCE(len + 1 >= outbuf_sz))
2733 return;
2734
> 2735 if (cmsg->outbuf_len + len >= outbuf_sz) {
2736 /* Truncate the message, but keep it terminated. */
2737 cmsg->outbuf_len = outbuf_sz - (len + 1);
2738 outbuf[cmsg->outbuf_len] = 0;
2739 }
2740
2741 memmove(outbuf + len, outbuf, cmsg->outbuf_len + 1);
2742 memcpy(outbuf, scratchbuf, len);
2743 cmsg->outbuf_len += len;
2744 }
2745
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests
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