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Mon, 25 Mar 2019 13:06:15 +0000 (UTC) Subject: Re: [PATCH] btrfs: use BUG() instead of BUG_ON(1) To: Arnd Bergmann , Chris Mason , Josef Bacik , David Sterba Cc: clang-built-linux@googlegroups.com, Nick Desaulniers , Nathan Chancellor , Qu Wenruo , Liu Bo , Filipe Manana , Johannes Thumshirn , Anand Jain , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190325130256.1437810-1-arnd@arndb.de> From: Nikolay Borisov Openpgp: preference=signencrypt Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= mQINBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABtCNOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuY29tPokCOAQTAQIAIgUCWIo48QIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQcb6CRuU/KFc0eg/9GLD3wTQz9iZHMFbjiqTCitD7B6dTLV1C ddZVlC8Hm/TophPts1bWZORAmYIihHHI1EIF19+bfIr46pvfTu0yFrJDLOADMDH+Ufzsfy2v HSqqWV/nOSWGXzh8bgg/ncLwrIdEwBQBN9SDS6aqsglagvwFD91UCg/TshLlRxD5BOnuzfzI Leyx2c6YmH7Oa1R4MX9Jo79SaKwdHt2yRN3SochVtxCyafDlZsE/efp21pMiaK1HoCOZTBp5 VzrIP85GATh18pN7YR9CuPxxN0V6IzT7IlhS4Jgj0NXh6vi1DlmKspr+FOevu4RVXqqcNTSS E2rycB2v6cttH21UUdu/0FtMBKh+rv8+yD49FxMYnTi1jwVzr208vDdRU2v7Ij/TxYt/v4O8 V+jNRKy5Fevca/1xroQBICXsNoFLr10X5IjmhAhqIH8Atpz/89ItS3+HWuE4BHB6RRLM0gy8 T7rN6ja+KegOGikp/VTwBlszhvfLhyoyjXI44Tf3oLSFM+8+qG3B7MNBHOt60CQlMkq0fGXd mm4xENl/SSeHsiomdveeq7cNGpHi6i6ntZK33XJLwvyf00PD7tip/GUj0Dic/ZUsoPSTF/mG EpuQiUZs8X2xjK/AS/l3wa4Kz2tlcOKSKpIpna7V1+CMNkNzaCOlbv7QwprAerKYywPCoOSC 7P25Ag0EWIoHPgEQAMiUqvRBZNvPvki34O/dcTodvLSyOmK/MMBDrzN8Cnk302XfnGlW/YAQ csMWISKKSpStc6tmD+2Y0z9WjyRqFr3EGfH1RXSv9Z1vmfPzU42jsdZn667UxrRcVQXUgoKg QYx055Q2FdUeaZSaivoIBD9WtJq/66UPXRRr4H/+Y5FaUZx+gWNGmBT6a0S/GQnHb9g3nonD jmDKGw+YO4P6aEMxyy3k9PstaoiyBXnzQASzdOi39BgWQuZfIQjN0aW+Dm8kOAfT5i/yk59h VV6v3NLHBjHVw9kHli3jwvsizIX9X2W8tb1SefaVxqvqO1132AO8V9CbE1DcVT8fzICvGi42 FoV/k0QOGwq+LmLf0t04Q0csEl+h69ZcqeBSQcIMm/Ir+NorfCr6HjrB6lW7giBkQl6hhomn l1mtDP6MTdbyYzEiBFcwQD4terc7S/8ELRRybWQHQp7sxQM/Lnuhs77MgY/e6c5AVWnMKd/z MKm4ru7A8+8gdHeydrRQSWDaVbfy3Hup0Ia76J9FaolnjB8YLUOJPdhI2vbvNCQ2ipxw3Y3c KhVIpGYqwdvFIiz0Fej7wnJICIrpJs/+XLQHyqcmERn3s/iWwBpeogrx2Lf8AGezqnv9woq7 OSoWlwXDJiUdaqPEB/HmGfqoRRN20jx+OOvuaBMPAPb+aKJyle8zABEBAAGJAh8EGAECAAkF AliKBz4CGwwACgkQcb6CRuU/KFdacg/+M3V3Ti9JYZEiIyVhqs+yHb6NMI1R0kkAmzsGQ1jU zSQUz9AVMR6T7v2fIETTT/f5Oout0+Hi9cY8uLpk8CWno9V9eR/B7Ifs2pAA8lh2nW43FFwp IDiSuDbH6oTLmiGCB206IvSuaQCp1fed8U6yuqGFcnf0ZpJm/sILG2ECdFK9RYnMIaeqlNQm iZicBY2lmlYFBEaMXHoy+K7nbOuizPWdUKoKHq+tmZ3iA+qL5s6Qlm4trH28/fPpFuOmgP8P K+7LpYLNSl1oQUr+WlqilPAuLcCo5Vdl7M7VFLMq4xxY/dY99aZx0ZJQYFx0w/6UkbDdFLzN upT7NIN68lZRucImffiWyN7CjH23X3Tni8bS9ubo7OON68NbPz1YIaYaHmnVQCjDyDXkQoKC R82Vf9mf5slj0Vlpf+/Wpsv/TH8X32ajva37oEQTkWNMsDxyw3aPSps6MaMafcN7k60y2Wk/ TCiLsRHFfMHFY6/lq/c0ZdOsGjgpIK0G0z6et9YU6MaPuKwNY4kBdjPNBwHreucrQVUdqRRm RcxmGC6ohvpqVGfhT48ZPZKZEWM+tZky0mO7bhZYxMXyVjBn4EoNTsXy1et9Y1dU3HVJ8fod 5UqrNrzIQFbdeM0/JqSLrtlTcXKJ7cYFa9ZM2AP7UIN9n1UWxq+OPY9YMOewVfYtL8M= Message-ID: <78cd318c-2094-87ca-4843-46af5e3d11ef@suse.com> Date: Mon, 25 Mar 2019 15:06:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190325130256.1437810-1-arnd@arndb.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25.03.19 г. 15:02 ч., Arnd Bergmann wrote: > BUG_ON(1) leads to bogus warnings from clang when > CONFIG_PROFILE_ANNOTATED_BRANCHES is set: > > fs/btrfs/volumes.c:5041:3: error: variable 'max_chunk_size' is used uninitialized whenever 'if' condition is false > [-Werror,-Wsometimes-uninitialized] > BUG_ON(1); > ^~~~~~~~~ > include/asm-generic/bug.h:61:36: note: expanded from macro 'BUG_ON' > #define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0) > ^~~~~~~~~~~~~~~~~~~ > include/linux/compiler.h:48:23: note: expanded from macro 'unlikely' > # define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x))) > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > fs/btrfs/volumes.c:5046:9: note: uninitialized use occurs here > max_chunk_size); > ^~~~~~~~~~~~~~ > include/linux/kernel.h:860:36: note: expanded from macro 'min' > #define min(x, y) __careful_cmp(x, y, <) > ^ > include/linux/kernel.h:853:17: note: expanded from macro '__careful_cmp' > __cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op)) > ^ > include/linux/kernel.h:847:25: note: expanded from macro '__cmp_once' > typeof(y) unique_y = (y); \ > ^ > fs/btrfs/volumes.c:5041:3: note: remove the 'if' if its condition is always true > BUG_ON(1); > ^ > include/asm-generic/bug.h:61:32: note: expanded from macro 'BUG_ON' > #define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0) > ^ > fs/btrfs/volumes.c:4993:20: note: initialize the variable 'max_chunk_size' to silence this warning > u64 max_chunk_size; > ^ > = 0 > > Change it to BUG() so clang can see that this code path can never > continue. Long-term we have to eliminate to bug_on's but until then: Reviewed-by: Nikolay Borisov > > Signed-off-by: Arnd Bergmann > --- > fs/btrfs/backref.c | 4 ++-- > fs/btrfs/ctree.c | 4 ++-- > fs/btrfs/extent_io.c | 8 ++++---- > fs/btrfs/file.c | 2 +- > fs/btrfs/inode.c | 2 +- > fs/btrfs/root-tree.c | 2 +- > fs/btrfs/volumes.c | 2 +- > 7 files changed, 12 insertions(+), 12 deletions(-) > > diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c > index 11459fe84a29..2602072ed906 100644 > --- a/fs/btrfs/backref.c > +++ b/fs/btrfs/backref.c > @@ -791,7 +791,7 @@ static int add_delayed_refs(const struct btrfs_fs_info *fs_info, > count = node->ref_mod * -1; > break; > default: > - BUG_ON(1); > + BUG(); > } > *total_refs += count; > switch (node->type) { > @@ -1747,7 +1747,7 @@ int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical, > else if (flags & BTRFS_EXTENT_FLAG_DATA) > *flags_ret = BTRFS_EXTENT_FLAG_DATA; > else > - BUG_ON(1); > + BUG(); > return 0; > } > > diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c > index 324df36d28bf..75c69829d975 100644 > --- a/fs/btrfs/ctree.c > +++ b/fs/btrfs/ctree.c > @@ -4674,7 +4674,7 @@ void btrfs_extend_item(struct btrfs_fs_info *fs_info, struct btrfs_path *path, > btrfs_print_leaf(leaf); > btrfs_crit(fs_info, "slot %d too large, nritems %d", > slot, nritems); > - BUG_ON(1); > + BUG(); > } > > /* > @@ -4754,7 +4754,7 @@ void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path, > btrfs_print_leaf(leaf); > btrfs_crit(fs_info, "slot %d old_data %d data_end %d", > slot, old_data, data_end); > - BUG_ON(1); > + BUG(); > } > /* > * item0..itemN ... dataN.offset..dataN.size .. data0.size > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > index ca8b8e785cf3..610a98857e22 100644 > --- a/fs/btrfs/extent_io.c > +++ b/fs/btrfs/extent_io.c > @@ -5746,13 +5746,13 @@ void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, > btrfs_err(fs_info, > "memmove bogus src_offset %lu move len %lu dst len %lu", > src_offset, len, dst->len); > - BUG_ON(1); > + BUG(); > } > if (dst_offset + len > dst->len) { > btrfs_err(fs_info, > "memmove bogus dst_offset %lu move len %lu dst len %lu", > dst_offset, len, dst->len); > - BUG_ON(1); > + BUG(); > } > > while (len > 0) { > @@ -5793,13 +5793,13 @@ void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, > btrfs_err(fs_info, > "memmove bogus src_offset %lu move len %lu len %lu", > src_offset, len, dst->len); > - BUG_ON(1); > + BUG(); > } > if (dst_offset + len > dst->len) { > btrfs_err(fs_info, > "memmove bogus dst_offset %lu move len %lu len %lu", > dst_offset, len, dst->len); > - BUG_ON(1); > + BUG(); > } > if (dst_offset < src_offset) { > memcpy_extent_buffer(dst, dst_offset, src_offset, len); > diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c > index 34fe8a58b0e9..f28aed471693 100644 > --- a/fs/btrfs/file.c > +++ b/fs/btrfs/file.c > @@ -1025,7 +1025,7 @@ int __btrfs_drop_extents(struct btrfs_trans_handle *trans, > continue; > } > > - BUG_ON(1); > + BUG(); > } > > if (!ret && del_nr > 0) { > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 82fdda8ff5ab..98bc66d34e6c 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -1451,7 +1451,7 @@ static noinline int run_delalloc_nocow(struct inode *inode, > extent_end = ALIGN(extent_end, > fs_info->sectorsize); > } else { > - BUG_ON(1); > + BUG(); > } > out_check: > if (extent_end <= start) { > diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c > index 893d12fbfda0..552efc88a016 100644 > --- a/fs/btrfs/root-tree.c > +++ b/fs/btrfs/root-tree.c > @@ -141,7 +141,7 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root > btrfs_print_leaf(path->nodes[0]); > btrfs_crit(fs_info, "unable to update root key %llu %u %llu", > key->objectid, key->type, key->offset); > - BUG_ON(1); > + BUG(); > } > > l = path->nodes[0]; > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index 9024eee889b9..95223fd9f9d0 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -5038,7 +5038,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans, > } else { > btrfs_err(info, "invalid chunk type 0x%llx requested", > type); > - BUG_ON(1); > + BUG(); > } > > /* We don't want a chunk larger than 10% of writable space */ >