linux-kernel - Re: [RFC PATCH 25/26] UBIFS: add debugging stuff

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Date:	Tue, 1 Apr 2008 00:00:55 +0300
From:	"Pekka Enberg" <penberg@...helsinki.fi>
To:	"Artem Bityutskiy" <Artem.Bityutskiy@...ia.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	"Adrian Hunter" <ext-adrian.hunter@...ia.com>
Subject: Re: [RFC PATCH 25/26] UBIFS: add debugging stuff

Hi Artem,

On Thu, Mar 27, 2008 at 5:55 PM, Artem Bityutskiy
<Artem.Bityutskiy@...ia.com> wrote:
> The UBIFS code is large, and we have a plenty of debugging stuff
>  in there which helps to catch bugs. Some of the debugging stuff
>  will be deleted later.

Yes please. The code is somewhat noisy on the debugging side.

On Thu, Mar 27, 2008 at 5:55 PM, Artem Bityutskiy
<Artem.Bityutskiy@...ia.com> wrote:
>  +void *dbg_kmalloc(size_t size, gfp_t flags)
>  +
>  +void *dbg_kzalloc(size_t size, gfp_t flags)
>  +
>  +void dbg_kfree(const void *addr)
>  +
>  +void *dbg_vmalloc(size_t size)
>  +
>  +void dbg_vfree(void *addr)
>  +
>  +void dbg_leak_report(void)

Not acceptable for mainline kernel. SLAB already provides leak
detection and it should be straight-forward to port over to SLUB too.

>  +/*
>  + * struct eaten_memory - memory object eaten by UBIFS to cause memory pressure.
>  + * @list: link in the list of eaten memory objects
>  + * @pad: just pads to memory page size
>  + */
>  +struct eaten_memory {
>  +       struct list_head list;
>  +       uint8_t pad[PAGE_CACHE_SIZE - sizeof(struct list_head)];
>  +};

If you need this, please make it a standalone module in mm/.

>  +void dbg_eat_memory(void)
>  +{
>  +       struct eaten_memory *em;
>  +
>  +       em = kmalloc(sizeof(struct eaten_memory), GFP_NOFS);

It's probably better to use the page allocator for this.

>  +#ifdef CONFIG_UBIFS_FS_DEBUG
>  +#define UBIFS_DBG(op) op
>  +#define ubifs_assert(expr)  do {                                               \
>  +
>  +/* Generic debugging message */
>  +#define dbg_msg(fmt, ...) do {                                                 \
>  +
>  +/* Debugging message which prints UBIFS key */
>  +#define dbg_key(c, key, fmt, ...) do {                                         \
>  +
>  +#define dbg_err(fmt, ...) ubifs_err(fmt, ##__VA_ARGS__)
>  +#define dbg_dump_stack() dump_stack()

Please kill these wrappers and use BUG_ON, WARN_ON, and printk() where
appropriate.
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