From: Oliver Neukum <oliver@neukum.org>
Organization: NOvell
To: Greg KH <greg@kroah.com>
Subject: Re: [PATCH] USB: add USB test and measurement class driver
Date: Wed, 27 Aug 2008 10:13:06 +0200
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Cc: linux-usb@vger.kernel.org, Stefan Kopp <stefan_kopp@agilent.com>,
       Marcel Janssen <korgull@home.nl>, Felipe Balbi <me@felipebalbi.com>,
       linux-kernel@vger.kernel.org
References: <20080827000501.GA29570@kroah.com>
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Am Mittwoch 27 August 2008 02:05:01 schrieb Greg KH:> +static ssize_t usbtmc_read(struct file *filp, char __user *buf,> +??????????????????????? ? size_t count, loff_t *f_pos)> +{> +???????struct usbtmc_device_data *data;> +???????struct device *dev;> +???????unsigned long int n_characters;> +???????u8 *buffer;> +???????int actual;> +???????int done;> +???????int remaining;> +???????int retval;> +???????int this_part;> +> +???????/* Get pointer to private data structure */> +???????data = filp->private_data;> +???????dev = &data->intf->dev;> +???????buffer = data->buffer;> +> +???????remaining = count;> +???????done = 0;> +> +???????while (remaining > 0) {> +???????????????if (remaining > USBTMC_SIZE_IOBUFFER - 12 - 3)> +???????????????????????this_part = USBTMC_SIZE_IOBUFFER - 12 - 3;> +???????????????else> +???????????????????????this_part = remaining;> +> +???????????????/* Setup IO buffer for DEV_DEP_MSG_IN message> +??????????????? * Refer to class specs for details> +??????????????? */> +???????????????buffer[0] = 2;> +???????????????buffer[1] = data->bTag;> +???????????????buffer[2] = ~(data->bTag);> +???????????????buffer[3] = 0; /* Reserved */> +???????????????buffer[4] = (this_part - 12 - 3) & 255;> +???????????????buffer[5] = ((this_part - 12 - 3) >> 8) & 255;> +???????????????buffer[6] = ((this_part - 12 - 3) >> 16) & 255;> +???????????????buffer[7] = ((this_part - 12 - 3) >> 24) & 255;> +???????????????buffer[8] = data->TermCharEnabled * 2;> +???????????????/* Use term character? */> +???????????????buffer[9] = data->TermChar;> +???????????????buffer[10] = 0; /* Reserved */> +???????????????buffer[11] = 0; /* Reserved */
This function will go bad if concurrent readers enter, yet it has no locking.
	Regards		Oliver
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