Re: [PATCH net-next] net: skb: prevent the split of kfree_skb_reason() by gcc
From: kernel test robot
Date: Thu Aug 11 2022 - 14:28:10 EST
Hi,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on net-next/master]
url: https://github.com/intel-lab-lkp/linux/commits/menglong8-dong-gmail-com/net-skb-prevent-the-split-of-kfree_skb_reason-by-gcc/20220811-200919
base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git f86d1fbbe7858884d6754534a0afbb74fc30bc26
config: riscv-randconfig-r042-20220811 (https://download.01.org/0day-ci/archive/20220812/202208120238.cz3RvV74-lkp@xxxxxxxxx/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 5f1c7e2cc5a3c07cbc2412e851a7283c1841f520)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install riscv cross compiling tool for clang build
# apt-get install binutils-riscv64-linux-gnu
# https://github.com/intel-lab-lkp/linux/commit/8e014b654d9e51abed132155237d855b25da06a0
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review menglong8-dong-gmail-com/net-skb-prevent-the-split-of-kfree_skb_reason-by-gcc/20220811-200919
git checkout 8e014b654d9e51abed132155237d855b25da06a0
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash net/core/
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>
All warnings (new ones prefixed by >>):
>> net/core/skbuff.c:780:6: warning: unknown attribute 'optimize' ignored [-Wunknown-attributes]
void __nofnsplit
^~~~~~~~~~~
include/linux/compiler_attributes.h:374:56: note: expanded from macro '__nofnsplit'
#define __nofnsplit __attribute__((optimize("O1")))
^~~~~~~~~~~~~~
1 warning generated.
vim +/optimize +780 net/core/skbuff.c
770
771 /**
772 * kfree_skb_reason - free an sk_buff with special reason
773 * @skb: buffer to free
774 * @reason: reason why this skb is dropped
775 *
776 * Drop a reference to the buffer and free it if the usage count has
777 * hit zero. Meanwhile, pass the drop reason to 'kfree_skb'
778 * tracepoint.
779 */
> 780 void __nofnsplit
781 kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
782 {
783 if (!skb_unref(skb))
784 return;
785
786 DEBUG_NET_WARN_ON_ONCE(reason <= 0 || reason >= SKB_DROP_REASON_MAX);
787
788 trace_kfree_skb(skb, __builtin_return_address(0), reason);
789 __kfree_skb(skb);
790 }
791 EXPORT_SYMBOL(kfree_skb_reason);
792
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https://01.org/lkp