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Message-ID: <20080419144952.GM20637@parisc-linux.org> Date: Sat, 19 Apr 2008 08:49:52 -0600 From: Matthew Wilcox <matthew@....cx> To: Julia Lawall <julia@...u.dk>, linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org Cc: Roel Kluin <12o3l@...cali.nl>, kernel-janitors@...r.kernel.org, kernelnewbies-bounce@...linux.org Subject: Re: script to find incorrect tests on unsigneds On Fri, Apr 18, 2008 at 09:08:55PM +0200, Julia Lawall wrote: > I found 63 occurrences of this problem with the following semantic match > (http://www.emn.fr/x-info/coccinelle/): > > @@ unsigned int i; @@ > > * i < 0 > > I looked through all of the results by hand, and they all seem to be > problems. In many cases, it seems like the variable should not be > unsigned as it is used to hold the return value of a function that might > return a negative error code, but I haven't looked into this in detail. > > In the output below, the lines that begin with a single start contain a > test of whether an unsigned variable or structure field is less than 0. > The output is actually generated with diff, but I converted the -s to *s > to avoid confusion. > diff -u -p a/fs/ext3/inode.c b/fs/ext3/inode.c > *** a/fs/ext3/inode.c 2008-03-12 14:13:14.000000000 +0100 > @@ -1263,7 +1263,7 @@ static int ext3_ordered_write_end(struct > EXT3_I(inode)->i_disksize = new_i_size; > copied = ext3_generic_write_end(file, mapping, pos, len, copied, > page, fsdata); > * if (copied < 0) > ret = copied; > } > ret2 = ext3_journal_stop(handle); > @@ -1291,7 +1291,7 @@ static int ext3_writeback_write_end(stru > > copied = ext3_generic_write_end(file, mapping, pos, len, copied, > page, fsdata); > * if (copied < 0) > ret = copied; > > ret2 = ext3_journal_stop(handle); > diff -u -p a/fs/ext4/inode.c b/fs/ext4/inode.c > *** a/fs/ext4/inode.c 2008-03-12 14:13:14.000000000 +0100 > @@ -1303,7 +1303,7 @@ static int ext4_ordered_write_end(struct > EXT4_I(inode)->i_disksize = new_i_size; > copied = ext4_generic_write_end(file, mapping, pos, len, copied, > page, fsdata); > * if (copied < 0) > ret = copied; > } > ret2 = ext4_journal_stop(handle); > @@ -1331,7 +1331,7 @@ static int ext4_writeback_write_end(stru > > copied = ext4_generic_write_end(file, mapping, pos, len, copied, > page, fsdata); > * if (copied < 0) > ret = copied; > > ret2 = ext4_journal_stop(handle); Fix comparisons of an unsigned int against 0 It's not really feasible to change 'copied' into a signed int, and while we could cast it for the purposes of this comparison, I think this rearrangement of the tests is actually clearer than the original. Reported-by: Julia Lawall <julia@...u.dk> Signed-off-by: Matthew Wilcox <willy@...ux.intel.com> diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c index eb95670..60f504b 100644 --- a/fs/ext3/inode.c +++ b/fs/ext3/inode.c @@ -1261,18 +1261,16 @@ static int ext3_ordered_write_end(struct file *file, new_i_size = pos + copied; if (new_i_size > EXT3_I(inode)->i_disksize) EXT3_I(inode)->i_disksize = new_i_size; - copied = ext3_generic_write_end(file, mapping, pos, len, copied, + ret = ext3_generic_write_end(file, mapping, pos, len, copied, page, fsdata); - if (copied < 0) - ret = copied; } ret2 = ext3_journal_stop(handle); - if (!ret) + if (ret >= 0 && ret2) ret = ret2; unlock_page(page); page_cache_release(page); - return ret ? ret : copied; + return ret; } static int ext3_writeback_write_end(struct file *file, @@ -1289,18 +1287,15 @@ static int ext3_writeback_write_end(struct file *file, if (new_i_size > EXT3_I(inode)->i_disksize) EXT3_I(inode)->i_disksize = new_i_size; - copied = ext3_generic_write_end(file, mapping, pos, len, copied, + ret = ext3_generic_write_end(file, mapping, pos, len, copied, page, fsdata); - if (copied < 0) - ret = copied; - ret2 = ext3_journal_stop(handle); - if (!ret) + if (ret >= 0 && ret2) ret = ret2; unlock_page(page); page_cache_release(page); - return ret ? ret : copied; + return ret; } static int ext3_journalled_write_end(struct file *file, diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 945cbf6..69b29c6 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1301,18 +1301,16 @@ static int ext4_ordered_write_end(struct file *file, new_i_size = pos + copied; if (new_i_size > EXT4_I(inode)->i_disksize) EXT4_I(inode)->i_disksize = new_i_size; - copied = ext4_generic_write_end(file, mapping, pos, len, copied, + ret = ext4_generic_write_end(file, mapping, pos, len, copied, page, fsdata); - if (copied < 0) - ret = copied; } ret2 = ext4_journal_stop(handle); - if (!ret) + if (ret >= 0 && ret2) ret = ret2; unlock_page(page); page_cache_release(page); - return ret ? ret : copied; + return ret; } static int ext4_writeback_write_end(struct file *file, @@ -1329,18 +1327,16 @@ static int ext4_writeback_write_end(struct file *file, if (new_i_size > EXT4_I(inode)->i_disksize) EXT4_I(inode)->i_disksize = new_i_size; - copied = ext4_generic_write_end(file, mapping, pos, len, copied, + ret = ext4_generic_write_end(file, mapping, pos, len, copied, page, fsdata); - if (copied < 0) - ret = copied; ret2 = ext4_journal_stop(handle); - if (!ret) + if (ret >= 0 && ret2) ret = ret2; unlock_page(page); page_cache_release(page); - return ret ? ret : copied; + return ret; } static int ext4_journalled_write_end(struct file *file, -- Intel are signing my paycheques ... these opinions are still mine "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. 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