linux-kernel - Re: [PATCH 5/9] mfd: Add UART support for the ST-Ericsson CG2900.

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Date:	Fri, 29 Oct 2010 13:53:57 +0200
From:	Par-Gunnar Hjalmdahl <pghatwork@...il.com>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	linus.walleij@...ricsson.com, linux-bluetooth@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/9] mfd: Add UART support for the ST-Ericsson CG2900.

2010/10/22 Alan Cox <alan@...rguk.ukuu.org.uk>:
>> +
>> +/**
>> + * create_work_item() - Create work item and add it to the work queue.
>> + * @wq:              work queue struct where the work will be added.
>> + * @work_func:       Work function.
>> + * @data:    Private data for the work.
>> + *
>> + * Returns:
>> + *   0 if there is no error.
>> + *   -EBUSY if not possible to queue work.
>> + *   -ENOMEM if allocation fails.
>> + */
>> +static int create_work_item(struct workqueue_struct *wq, work_func_t work_func,
>> +                         void *data)
>> +{
>> +     struct uart_work_struct *new_work;
>> +     int err;
>> +
>> +     new_work = kmalloc(sizeof(*new_work), GFP_ATOMIC);
>
> So instead of a tiny object embedded in your device you've got a whole
> error path to worry about, a printk disguised in a macro and a text
> string longer than the struct size ? Surely this should be part of the
> device
>

I've tried now to use 3 separate work_structs in the device (one for
each work function used), but this doesn't work out.
The reason is that the work is generated so often that a work is not
finished before next work of same type comes. This is especially true
for transmit and receive. Then I get 0 back when queuing the work and
there is no real way to solve it from what I can see than to allocate
new work structures every time.

/P-G
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