From: Matthew Wilcox <willy@infradead.org>
To: Joe Perches <joe@perches.com>
Cc: Dave Chinner <david@fromorbit.com>,
Alan Stern <stern@rowland.harvard.edu>,
Byungchul Park <byungchul.park@lge.com>,
"Theodore Ts'o" <tytso@mit.edu>,
Matthew Wilcox <mawilcox@microsoft.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Jens Axboe <axboe@kernel.dk>, Rehas Sachdeva <aquannie@gmail.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org,
linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@lge.com
Subject: Re: [PATCH v4 72/73] xfs: Convert mru cache to XArray
Date: Mon, 11 Dec 2017 14:43:01 -0800 [thread overview]
Message-ID: <20171211224301.GA3925@bombadil.infradead.org> (raw)
In-Reply-To: <1513030348.3036.5.camel@perches.com>
On Mon, Dec 11, 2017 at 02:12:28PM -0800, Joe Perches wrote:
> Completely reasonable. Thanks.
If we're doing "completely reasonable" complaints, then ...
- I don't understand why plain 'unsigned' is deemed bad.
- The rule about all function parameters in prototypes having a name
doesn't make sense. Example:
int ida_get_new_above(struct ida *ida, int starting_id, int *p_id);
There is zero additional value in naming 'ida'. I know it's an ida.
The struct name tells me that. If there're two struct ida pointers
in the prototype, then sure, I want to name them so I know which is
which (maybe 'src' and 'dst'). Having an unadorned 'int' parameter
to a function should be a firable offence. But there's no need to
call 'gfp_t' anything. We know it's a gfp_t. Adding 'gfp_mask'
after it doesn't tell us anything extra.
- Forcing a blank line after variable declarations sometimes makes for
some weird-looking code. For example, there is no problem with this
code (from a checkpatch PoV):
if (xa_is_sibling(entry)) {
offset = xa_to_sibling(entry);
entry = xa_entry(xas->xa, node, offset);
/* Move xa_index to the first index of this entry */
xas->xa_index = (((xas->xa_index >> node->shift) &
~XA_CHUNK_MASK) | offset) << node->shift;
}
but if I decide I don't need 'offset' outside this block, and I want
to move the declaration inside, it looks like this:
if (xa_is_sibling(entry)) {
unsigned int offset = xa_to_sibling(entry);
entry = xa_entry(xas->xa, node, offset);
/* Move xa_index to the first index of this entry */
xas->xa_index = (((xas->xa_index >> node->shift) &
~XA_CHUNK_MASK) | offset) << node->shift;
}
Does that blank line really add anything to your comprehension of the
block? It upsets my train of thought.
Constructively, I think this warning can be suppressed for blocks
that are under, say, 8 lines. Or maybe indented blocks is where I don't
want this warning. Not sure.
Here's another example where I don't think the blank line adds anything:
static inline int xa_store_empty(struct xarray *xa, unsigned long index,
void *entry, gfp_t gfp, int errno)
{
void *curr = xa_cmpxchg(xa, index, NULL, entry, gfp);
if (!curr)
return 0;
if (xa_is_err(curr))
return xa_err(curr);
return errno;
}
So line count definitely has something to do with it.
- There's no warning for the first paragraph of section 6:
6) Functions
------------
Functions should be short and sweet, and do just one thing. They should
fit on one or two screenfuls of text (the ISO/ANSI screen size is 80x24,
as we all know), and do one thing and do that well.
I'm not expecting you to be able to write a perl script that checks
the first line, but we have way too many 200-plus line functions in
the kernel. I'd like a warning on anything over 200 lines (a factor
of 4 over Linus's stated goal).
- I don't understand the error for xa_head here:
struct xarray {
spinlock_t xa_lock;
gfp_t xa_flags;
void __rcu * xa_head;
};
Do people really think that:
struct xarray {
spinlock_t xa_lock;
gfp_t xa_flags;
void __rcu *xa_head;
};
is more aesthetically pleasing? And not just that, but it's an *error*
so the former is *RIGHT* and this is *WRONG*. And not just a matter
of taste?
next prev parent reply other threads:[~2017-12-11 22:43 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-06 0:40 [PATCH v4 00/73] XArray version 4 Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 01/73] xfs: Rename xa_ elements to ail_ Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 02/73] xarray: Add the xa_lock to the radix_tree_root Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 03/73] page cache: Use xa_lock Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 04/73] xarray: Replace exceptional entries Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 05/73] xarray: Change definition of sibling entries Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 06/73] xarray: Add definition of struct xarray Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 07/73] xarray: Define struct xa_node Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 08/73] xarray: Add documentation Matthew Wilcox
2017-12-11 23:10 ` Randy Dunlap
2017-12-15 4:22 ` Matthew Wilcox
2017-12-15 12:34 ` Naming of tag operations in the XArray Matthew Wilcox
2017-12-19 0:16 ` Randy Dunlap
2017-12-15 17:10 ` Storing errors " Matthew Wilcox
2017-12-19 0:27 ` Randy Dunlap
2017-12-06 0:40 ` [PATCH v4 09/73] xarray: Add xa_load Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 10/73] xarray: Add xa_get_tag, xa_set_tag and xa_clear_tag Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 11/73] xarray: Add xa_store Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 12/73] xarray: Add xa_cmpxchg Matthew Wilcox
2017-12-06 0:40 ` [PATCH v4 13/73] xarray: Add xa_for_each Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 14/73] xarray: Add xas_for_each_tag Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 15/73] xarray: Add xa_get_entries, xa_get_tagged and xa_get_maybe_tag Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 16/73] xarray: Add xa_destroy Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 17/73] xarray: Add xas_next and xas_prev Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 18/73] xarray: Add xas_create_range Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 19/73] xarray: Add MAINTAINERS entry Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 20/73] idr: Convert to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 21/73] ida: " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 22/73] page cache: Convert hole search " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 23/73] page cache: Add page_cache_range_empty function Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 24/73] page cache: Add and replace pages using the XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 25/73] page cache: Convert page deletion to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 26/73] page cache: Convert page cache lookups " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 27/73] page cache: Convert delete_batch " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 28/73] page cache: Remove stray radix comment Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 29/73] mm: Convert page-writeback to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 30/73] mm: Convert workingset " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 31/73] mm: Convert truncate " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 32/73] mm: Convert add_to_swap_cache " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 33/73] mm: Convert delete_from_swap_cache " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 34/73] mm: Convert cgroup writeback " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 35/73] mm: Convert __do_page_cache_readahead " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 36/73] mm: Convert page migration " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 37/73] mm: Convert huge_memory " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 38/73] mm: Convert collapse_shmem " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 39/73] mm: Convert khugepaged_scan_shmem " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 40/73] pagevec: Use xa_tag_t Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 41/73] shmem: Convert replace to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 42/73] shmem: Convert shmem_confirm_swap " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 43/73] shmem: Convert find_swap_entry " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 44/73] shmem: Convert shmem_tag_pins " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 45/73] shmem: Convert shmem_wait_for_pins " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 46/73] shmem: Convert shmem_add_to_page_cache " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 47/73] shmem: Convert shmem_alloc_hugepage " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 48/73] shmem: Convert shmem_free_swap " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 49/73] shmem: Convert shmem_partial_swap_usage " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 50/73] shmem: Comment fixups Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 51/73] btrfs: Convert page cache to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 52/73] fs: Convert buffer " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 53/73] fs: Convert writeback " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 54/73] nilfs2: Convert " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 55/73] f2fs: " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 56/73] lustre: " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 57/73] dax: Convert dax_unlock_mapping_entry " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 58/73] dax: Convert lock_slot " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 59/73] dax: More XArray conversion Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 60/73] dax: Convert __dax_invalidate_mapping_entry to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 61/73] dax: Convert dax_writeback_one " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 62/73] dax: Convert dax_insert_pfn_mkwrite " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 63/73] dax: Convert dax_insert_mapping_entry " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 64/73] dax: Convert grab_mapping_entry " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 65/73] dax: Fix sparse warning Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 66/73] page cache: Finish XArray conversion Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 67/73] vmalloc: Convert to XArray Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 68/73] brd: " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 69/73] xfs: Convert m_perag_tree " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 70/73] xfs: Convert pag_ici_root " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 71/73] xfs: Convert xfs dquot " Matthew Wilcox
2017-12-06 0:41 ` [PATCH v4 72/73] xfs: Convert mru cache " Matthew Wilcox
2017-12-06 1:36 ` Dave Chinner
2017-12-06 2:02 ` Matthew Wilcox
2017-12-06 3:14 ` Dave Chinner
2017-12-06 4:45 ` Matthew Wilcox
2017-12-06 4:52 ` Matthew Wilcox
2017-12-06 8:44 ` Dave Chinner
2017-12-06 14:06 ` Matthew Wilcox
2017-12-07 0:38 ` Dave Chinner
2017-12-08 23:01 ` Matthew Wilcox
2017-12-10 23:57 ` Dave Chinner
2017-12-11 4:23 ` Matthew Wilcox
2017-12-11 21:55 ` Dave Chinner
2017-12-07 16:06 ` Theodore Ts'o
2017-12-07 22:22 ` Dave Chinner
2017-12-08 4:45 ` Byungchul Park
2017-12-08 7:25 ` Dave Chinner
2017-12-08 9:27 ` Byungchul Park
2017-12-08 17:35 ` Alan Stern
2017-12-08 22:36 ` Dave Chinner
2017-12-09 17:00 ` Joe Perches
2017-12-11 21:43 ` Dave Chinner
2017-12-11 22:12 ` Joe Perches
2017-12-11 22:43 ` Matthew Wilcox [this message]
2017-12-11 23:46 ` Joe Perches
2017-12-12 15:51 ` Alan Stern
2017-12-14 18:23 ` Joe Perches
2017-12-17 1:26 ` [RFC patch] checkpatch: Add a test for long function definitions (>200 lines) Joe Perches
2017-12-17 21:46 ` Linus Torvalds
2017-12-17 22:22 ` Joe Perches
2017-12-17 22:33 ` Luc Van Oostenryck
2017-12-11 23:38 ` [PATCH v4 72/73] xfs: Convert mru cache to XArray Dave Chinner
2017-12-21 12:05 ` Knut Omang
2017-12-07 22:38 ` Lockdep is less useful than it was Matthew Wilcox
2017-12-07 22:39 ` Matthew Wilcox
2017-12-08 0:14 ` Dave Chinner
2017-12-08 15:27 ` Theodore Ts'o
2017-12-08 18:14 ` Matthew Wilcox
2017-12-08 22:47 ` Dave Chinner
2017-12-06 0:41 ` [PATCH v4 73/73] usb: Convert xhci-mem to XArray Matthew Wilcox
2017-12-06 1:45 ` [PATCH v4 00/73] XArray version 4 Dave Chinner
2017-12-06 1:51 ` Dave Chinner
2017-12-06 1:53 ` Matthew Wilcox
2017-12-06 2:17 ` Dave Chinner
2017-12-06 2:27 ` Matthew Wilcox
2017-12-06 2:05 ` Matthew Wilcox
2017-12-06 2:38 ` Dave Chinner
2017-12-06 23:58 ` Ross Zwisler
2017-12-07 0:13 ` Matthew Wilcox
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