linux-kernel - Re: [PATCH] eventfd: check ida_simple

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Date:   Wed, 7 Sep 2022 15:39:08 +0800
From:   kernel test robot <lkp@...el.com>
To:     Bo Liu <liubo03@...pur.com>, viro@...iv.linux.org.uk
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bo Liu <liubo03@...pur.com>
Subject: Re: [PATCH] eventfd: check ida_simple_get() return value

Hi Bo,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.0-rc4 next-20220906]
[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/Bo-Liu/eventfd-check-ida_simple_get-return-value/20220907-103955
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 0066f1b0e27556381402db3ff31f85d2a2265858
config: hexagon-randconfig-r041-20220906
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project c55b41d5199d2394dd6cdb8f52180d8b81d809d4)
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
        # https://github.com/intel-lab-lkp/linux/commit/04c5de6820d9c8b7e64a74150d30406cf7f43511
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Bo-Liu/eventfd-check-ida_simple_get-return-value/20220907-103955
        git checkout 04c5de6820d9c8b7e64a74150d30406cf7f43511
        # 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=hexagon SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

>> fs/eventfd.c:427:6: warning: variable 'fd' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (ctx->id < 0)
               ^~~~~~~~~~~
   fs/eventfd.c:448:9: note: uninitialized use occurs here
           return fd;
                  ^~
   fs/eventfd.c:427:2: note: remove the 'if' if its condition is always false
           if (ctx->id < 0)
           ^~~~~~~~~~~~~~~~
   fs/eventfd.c:409:8: note: initialize the variable 'fd' to silence this warning
           int fd;
                 ^
                  = 0
   1 warning generated.


vim +427 fs/eventfd.c

   404	
   405	static int do_eventfd(unsigned int count, int flags)
   406	{
   407		struct eventfd_ctx *ctx;
   408		struct file *file;
   409		int fd;
   410	
   411		/* Check the EFD_* constants for consistency.  */
   412		BUILD_BUG_ON(EFD_CLOEXEC != O_CLOEXEC);
   413		BUILD_BUG_ON(EFD_NONBLOCK != O_NONBLOCK);
   414	
   415		if (flags & ~EFD_FLAGS_SET)
   416			return -EINVAL;
   417	
   418		ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
   419		if (!ctx)
   420			return -ENOMEM;
   421	
   422		kref_init(&ctx->kref);
   423		init_waitqueue_head(&ctx->wqh);
   424		ctx->count = count;
   425		ctx->flags = flags;
   426		ctx->id = ida_simple_get(&eventfd_ida, 0, 0, GFP_KERNEL);
 > 427		if (ctx->id < 0)
   428			goto err;
   429	
   430		flags &= EFD_SHARED_FCNTL_FLAGS;
   431		flags |= O_RDWR;
   432		fd = get_unused_fd_flags(flags);
   433		if (fd < 0)
   434			goto err;
   435	
   436		file = anon_inode_getfile("[eventfd]", &eventfd_fops, ctx, flags);
   437		if (IS_ERR(file)) {
   438			put_unused_fd(fd);
   439			fd = PTR_ERR(file);
   440			goto err;
   441		}
   442	
   443		file->f_mode |= FMODE_NOWAIT;
   444		fd_install(fd, file);
   445		return fd;
   446	err:
   447		eventfd_free_ctx(ctx);
   448		return fd;
   449	}
   450	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp

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