linux-kernel - Re: [RFC][PATCH 1/1] support for user-space buffers in kfifo

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Message-Id: <1181686346.7991.3.camel@voyager.dsnet>
Date:	Wed, 13 Jun 2007 00:12:26 +0200
From:	Stelian Pop <stelian@...ies.net>
To:	Nelson Castillo <nelsoneci@...il.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC][PATCH 1/1] support for user-space buffers in kfifo

Le mardi 12 juin 2007 à 11:24 -0500, Nelson Castillo a écrit :
> On 6/12/07, Stelian Pop <stelian@...ies.net> wrote:
> (cut)
> > accessing userspace memory with a spinlock taken (moreover an
> > irqsave()
> > one) is bad bad bad.
> 
> Hi Stelian.
> 
> I'm sending the new patch without kfifo_put_user and kfifo_get_user.

Ok, I have a few formatting/documentation comments:

> + * This function copies at most @len bytes from the @buffer into
> + * the FIFO depending on the free space, and returns the number of
> + * bytes copied.

... or -EFAULT if copy_from_user fails

> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these functions.
> + */
> +int __kfifo_put_user(struct kfifo *fifo, const unsigned char __user *buffer,
> +	        unsigned int len)

spacing ?

> +	if(copy_from_user(fifo->buffer + (fifo->in & (fifo->size - 1)),
> +			  buffer, l))

leave a space after the if please

> + * This function copies at most @len bytes from the FIFO into the
> + * @buffer and returns the number of copied bytes.

or -EFAULT

> + *
> + * Note that with only one concurrent reader and one concurrent
> + * writer, you don't need extra locking to use these functions.
> + */
> +
> +int __kfifo_get_user(struct kfifo *fifo,
> +			 unsigned char __user *buffer, unsigned int len)

spacing.

Other than that I'm ok with this patch.

Thanks,

Stelian.
-- 
Stelian Pop <stelian@...ies.net>

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