Messages in this thread | | | Date | Wed, 27 Aug 2008 09:08:54 -0700 | From | Greg KH <> | Subject | Re: [PATCH] USB: add USB test and measurement class driver |
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On Wed, Aug 27, 2008 at 10:13:06AM +0200, Oliver Neukum wrote: > 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.
Now fixed with an i/o mutex.
thanks,
greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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