Re: [PATCH][v5] HP iLO driver

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 2 Jul 2008 09:38:53 -0600 David Altobelli <david.altobelli@hp.com> wrote:

> A driver for the HP iLO/iLO2 management processor, which allows userspace
> programs to query the management processor.  Programs can open a channel
> to the device (/dev/hpilo/dXccbN), and use this to send/receive queries.  
> The O_EXCL open flag is used to indicate that a particular channel cannot
> be shared between processes.  This driver will replace various packages
> HP has shipped, including hprsm and hp-ilo.
> 
> 	v4 -> v5
> 	Converted more macros to inline functions
> 	Reorganized to remove kzalloc under spinlock
> 
> 	v3 -> v4
> 	Removed an upper case variable and some extra parens
> 	Converted some macros to inline functions
> 
> 	v2 -> v3
> 	Moved code from drivers/char to drivers/misc
> 
> 	v1 -> v2
> 	Changed device path to /dev/hpilo/dXccbN.
> 	Removed a volatile from fifobar variable.
> 	Changed ILO_NAME to remove spaces.
> 
>
> ...
>
> +static ssize_t ilo_write(struct file *fp, const char __user *buf,
> +			 size_t len, loff_t *off)
> +{
> +	int err, pkt_id, pkt_len;
> +	struct ccb_data *data;
> +	struct ccb *driver_ccb;
> +	struct ilo_hwinfo *hw;
> +	void *pkt;
> +
> +	data = fp->private_data;
> +	driver_ccb = &data->driver_ccb;
> +	hw = data->ilo_hw;
> +
> +	if (is_device_reset(hw) || is_channel_reset(driver_ccb)) {
> +		/*
> +		 * If the device has been reset, applications
> +		 * need to close and reopen all ccbs.
> +		 */
> +		ilo_reset(hw);
> +		return -ENODEV;
> +	}

Can multiple processes open and write to this "device"?  If so, the above
looks awfully racy.  Perhaps vfs-level i_mutex coverage will save us on the
write-versus-write side, but not on write-versus-read.