linux-kernel - Re: [PATCH] tty/sysrq: Dump kernel ring buffer messages via sysrq

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Date: Sun, 24 Dec 2023 22:22:19 +0800
From: kernel test robot <lkp@...el.com>
To: Sreenath Vijayan <sreenath.vijayan@...y.com>, linux-doc@...r.kernel.org,
	linux-serial@...r.kernel.org, corbet@....net,
	gregkh@...uxfoundation.org, jirislaby@...nel.org
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
	linux-kernel@...r.kernel.org, anandakumar.balasubramaniam@...y.com,
	Sreenath Vijayan <sreenath.vijayan@...y.com>,
	Shimoyashiki Taichi <taichi.shimoyashiki@...y.com>
Subject: Re: [PATCH] tty/sysrq: Dump kernel ring buffer messages via sysrq

Hi Sreenath,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tty/tty-testing]
[also build test WARNING on tty/tty-next tty/tty-linus linus/master v6.7-rc7 next-20231222]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Sreenath-Vijayan/tty-sysrq-Dump-kernel-ring-buffer-messages-via-sysrq/20231222-172636
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing
patch link:    https://lore.kernel.org/r/20231221133953.1507021-1-sreenath.vijayan%40sony.com
patch subject: [PATCH] tty/sysrq: Dump kernel ring buffer messages via sysrq
config: arm-defconfig (https://download.01.org/0day-ci/archive/20231224/202312242257.5c0xsTqe-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project.git f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231224/202312242257.5c0xsTqe-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202312242257.5c0xsTqe-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/tty/sysrq.c:455:13: warning: stack frame size (1088) exceeds limit (1024) in 'dmesg_dump_callback' [-Wframe-larger-than]
   static void dmesg_dump_callback(struct work_struct *work)
               ^
   1 warning generated.


vim +/dmesg_dump_callback +455 drivers/tty/sysrq.c

   454	
 > 455	static void dmesg_dump_callback(struct work_struct *work)
   456	{
   457		struct kmsg_dump_iter iter;
   458		size_t len;
   459		char buf[1024];
   460		struct console *con;
   461		int cookie;
   462	
   463		kmsg_dump_rewind(&iter);
   464		while (kmsg_dump_get_line(&iter, 1, buf, sizeof(buf), &len)) {
   465			/*
   466			 * Since using printk() or pr_*() will append the message to the
   467			 * kernel ring buffer, they cannot be used to display the retrieved
   468			 * message. Hence console_write() of serial drivers is used.
   469			 */
   470			console_lock();
   471			cookie = console_srcu_read_lock();
   472			for_each_console_srcu(con) {
   473				if ((console_srcu_read_flags(con) & CON_ENABLED) && con->write)
   474					con->write(con, buf, len);
   475			}
   476			console_srcu_read_unlock(cookie);
   477			console_unlock();
   478		}
   479	}
   480	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki