usb: usbtmc: Support Read Status Byte with SRQ per file
Add 'struct usbtmc_file_data' for each file handle to cache last srq_byte (=Status Byte with SRQ) received by usbtmc_interrupt(..) usbtmc488_ioctl_read_stb returns cached srq_byte when available for each file handle to avoid race conditions of concurrent applications. SRQ now sets EPOLLPRI instead of EPOLLIN since EPOLLIN is now reserved for asynchronous reads Tested-by: Dave Penkler <dpenkler@gmail.com> Reviewed-by: Steve Bayless <steve_bayless@keysight.com> Signed-off-by: Guido Kiener <guido.kiener@rohde-schwarz.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Guido Kiener
Greg Kroah-Hartman
parent
04b453c859
commit
4f3c8d6edd
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@ -67,6 +67,7 @@ struct usbtmc_device_data {
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const struct usb_device_id *id;
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struct usb_device *usb_dev;
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struct usb_interface *intf;
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struct list_head file_list;
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unsigned int bulk_in;
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unsigned int bulk_out;
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@ -87,7 +88,6 @@ struct usbtmc_device_data {
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int iin_interval;
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struct urb *iin_urb;
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u16 iin_wMaxPacketSize;
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atomic_t srq_asserted;
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/* coalesced usb488_caps from usbtmc_dev_capabilities */
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__u8 usb488_caps;
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@ -104,9 +104,21 @@ struct usbtmc_device_data {
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struct mutex io_mutex; /* only one i/o function running at a time */
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wait_queue_head_t waitq;
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struct fasync_struct *fasync;
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spinlock_t dev_lock; /* lock for file_list */
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};
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#define to_usbtmc_data(d) container_of(d, struct usbtmc_device_data, kref)
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/*
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* This structure holds private data for each USBTMC file handle.
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*/
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struct usbtmc_file_data {
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struct usbtmc_device_data *data;
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struct list_head file_elem;
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u8 srq_byte;
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atomic_t srq_asserted;
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};
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/* Forward declarations */
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static struct usb_driver usbtmc_driver;
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@ -122,7 +134,7 @@ static int usbtmc_open(struct inode *inode, struct file *filp)
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{
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struct usb_interface *intf;
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struct usbtmc_device_data *data;
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int retval = 0;
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struct usbtmc_file_data *file_data;
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intf = usb_find_interface(&usbtmc_driver, iminor(inode));
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if (!intf) {
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@ -130,21 +142,45 @@ static int usbtmc_open(struct inode *inode, struct file *filp)
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return -ENODEV;
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}
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file_data = kzalloc(sizeof(*file_data), GFP_KERNEL);
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if (!file_data)
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return -ENOMEM;
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data = usb_get_intfdata(intf);
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/* Protect reference to data from file structure until release */
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kref_get(&data->kref);
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/* Store pointer in file structure's private data field */
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filp->private_data = data;
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mutex_lock(&data->io_mutex);
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file_data->data = data;
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return retval;
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INIT_LIST_HEAD(&file_data->file_elem);
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spin_lock_irq(&data->dev_lock);
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list_add_tail(&file_data->file_elem, &data->file_list);
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spin_unlock_irq(&data->dev_lock);
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mutex_unlock(&data->io_mutex);
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/* Store pointer in file structure's private data field */
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filp->private_data = file_data;
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return 0;
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}
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static int usbtmc_release(struct inode *inode, struct file *file)
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{
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struct usbtmc_device_data *data = file->private_data;
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struct usbtmc_file_data *file_data = file->private_data;
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kref_put(&data->kref, usbtmc_delete);
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/* prevent IO _AND_ usbtmc_interrupt */
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mutex_lock(&file_data->data->io_mutex);
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spin_lock_irq(&file_data->data->dev_lock);
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list_del(&file_data->file_elem);
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spin_unlock_irq(&file_data->data->dev_lock);
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mutex_unlock(&file_data->data->io_mutex);
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kref_put(&file_data->data->kref, usbtmc_delete);
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file_data->data = NULL;
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kfree(file_data);
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return 0;
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}
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@ -369,10 +405,12 @@ static int usbtmc_ioctl_abort_bulk_out(struct usbtmc_device_data *data)
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return rv;
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}
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static int usbtmc488_ioctl_read_stb(struct usbtmc_device_data *data,
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static int usbtmc488_ioctl_read_stb(struct usbtmc_file_data *file_data,
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void __user *arg)
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{
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struct usbtmc_device_data *data = file_data->data;
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struct device *dev = &data->intf->dev;
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int srq_asserted = 0;
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u8 *buffer;
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u8 tag;
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__u8 stb;
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@ -381,15 +419,25 @@ static int usbtmc488_ioctl_read_stb(struct usbtmc_device_data *data,
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dev_dbg(dev, "Enter ioctl_read_stb iin_ep_present: %d\n",
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data->iin_ep_present);
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spin_lock_irq(&data->dev_lock);
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srq_asserted = atomic_xchg(&file_data->srq_asserted, srq_asserted);
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if (srq_asserted) {
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/* a STB with SRQ is already received */
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stb = file_data->srq_byte;
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spin_unlock_irq(&data->dev_lock);
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rv = put_user(stb, (__u8 __user *)arg);
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dev_dbg(dev, "stb:0x%02x with srq received %d\n",
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(unsigned int)stb, rv);
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return rv;
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}
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spin_unlock_irq(&data->dev_lock);
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buffer = kmalloc(8, GFP_KERNEL);
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if (!buffer)
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return -ENOMEM;
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atomic_set(&data->iin_data_valid, 0);
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/* must issue read_stb before using poll or select */
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atomic_set(&data->srq_asserted, 0);
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rv = usb_control_msg(data->usb_dev,
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usb_rcvctrlpipe(data->usb_dev, 0),
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USBTMC488_REQUEST_READ_STATUS_BYTE,
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@ -435,9 +483,8 @@ static int usbtmc488_ioctl_read_stb(struct usbtmc_device_data *data,
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stb = buffer[2];
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}
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rv = copy_to_user(arg, &stb, sizeof(stb));
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if (rv)
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rv = -EFAULT;
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rv = put_user(stb, (__u8 __user *)arg);
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dev_dbg(dev, "stb:0x%02x received %d\n", (unsigned int)stb, rv);
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exit:
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/* bump interrupt bTag */
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@ -565,6 +612,7 @@ static int send_request_dev_dep_msg_in(struct usbtmc_device_data *data, size_t t
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static ssize_t usbtmc_read(struct file *filp, char __user *buf,
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size_t count, loff_t *f_pos)
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{
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struct usbtmc_file_data *file_data;
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struct usbtmc_device_data *data;
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struct device *dev;
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u32 n_characters;
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@ -576,7 +624,8 @@ static ssize_t usbtmc_read(struct file *filp, char __user *buf,
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size_t this_part;
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/* Get pointer to private data structure */
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data = filp->private_data;
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file_data = filp->private_data;
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data = file_data->data;
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dev = &data->intf->dev;
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buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
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@ -721,6 +770,7 @@ static ssize_t usbtmc_read(struct file *filp, char __user *buf,
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static ssize_t usbtmc_write(struct file *filp, const char __user *buf,
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size_t count, loff_t *f_pos)
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{
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struct usbtmc_file_data *file_data;
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struct usbtmc_device_data *data;
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u8 *buffer;
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int retval;
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@ -730,7 +780,8 @@ static ssize_t usbtmc_write(struct file *filp, const char __user *buf,
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int done;
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int this_part;
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data = filp->private_data;
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file_data = filp->private_data;
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data = file_data->data;
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buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
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if (!buffer)
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@ -1140,10 +1191,13 @@ static int usbtmc_ioctl_indicator_pulse(struct usbtmc_device_data *data)
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static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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struct usbtmc_file_data *file_data;
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struct usbtmc_device_data *data;
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int retval = -EBADRQC;
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data = file->private_data;
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file_data = file->private_data;
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data = file_data->data;
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mutex_lock(&data->io_mutex);
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if (data->zombie) {
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retval = -ENODEV;
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@ -1184,7 +1238,8 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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break;
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case USBTMC488_IOCTL_READ_STB:
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retval = usbtmc488_ioctl_read_stb(data, (void __user *)arg);
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retval = usbtmc488_ioctl_read_stb(file_data,
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(void __user *)arg);
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break;
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case USBTMC488_IOCTL_REN_CONTROL:
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@ -1210,14 +1265,15 @@ static long usbtmc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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static int usbtmc_fasync(int fd, struct file *file, int on)
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{
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struct usbtmc_device_data *data = file->private_data;
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struct usbtmc_file_data *file_data = file->private_data;
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return fasync_helper(fd, file, on, &data->fasync);
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return fasync_helper(fd, file, on, &file_data->data->fasync);
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}
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static __poll_t usbtmc_poll(struct file *file, poll_table *wait)
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{
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struct usbtmc_device_data *data = file->private_data;
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struct usbtmc_file_data *file_data = file->private_data;
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struct usbtmc_device_data *data = file_data->data;
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__poll_t mask;
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mutex_lock(&data->io_mutex);
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@ -1229,7 +1285,7 @@ static __poll_t usbtmc_poll(struct file *file, poll_table *wait)
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poll_wait(file, &data->waitq, wait);
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mask = (atomic_read(&data->srq_asserted)) ? EPOLLIN | EPOLLRDNORM : 0;
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mask = (atomic_read(&file_data->srq_asserted)) ? EPOLLPRI : 0;
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no_poll:
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mutex_unlock(&data->io_mutex);
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@ -1276,15 +1332,33 @@ static void usbtmc_interrupt(struct urb *urb)
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}
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/* check for SRQ notification */
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if (data->iin_buffer[0] == 0x81) {
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unsigned long flags;
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struct list_head *elem;
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if (data->fasync)
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kill_fasync(&data->fasync,
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SIGIO, POLL_IN);
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SIGIO, POLL_PRI);
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atomic_set(&data->srq_asserted, 1);
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wake_up_interruptible(&data->waitq);
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spin_lock_irqsave(&data->dev_lock, flags);
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list_for_each(elem, &data->file_list) {
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struct usbtmc_file_data *file_data;
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file_data = list_entry(elem,
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struct usbtmc_file_data,
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file_elem);
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file_data->srq_byte = data->iin_buffer[1];
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atomic_set(&file_data->srq_asserted, 1);
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}
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spin_unlock_irqrestore(&data->dev_lock, flags);
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dev_dbg(dev, "srq received bTag %x stb %x\n",
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(unsigned int)data->iin_buffer[0],
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(unsigned int)data->iin_buffer[1]);
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wake_up_interruptible_all(&data->waitq);
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goto exit;
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}
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dev_warn(dev, "invalid notification: %x\n", data->iin_buffer[0]);
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dev_warn(dev, "invalid notification: %x\n",
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data->iin_buffer[0]);
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break;
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case -EOVERFLOW:
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dev_err(dev, "overflow with length %d, actual length is %d\n",
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@ -1295,6 +1369,7 @@ static void usbtmc_interrupt(struct urb *urb)
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case -ESHUTDOWN:
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case -EILSEQ:
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case -ETIME:
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case -EPIPE:
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/* urb terminated, clean up */
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dev_dbg(dev, "urb terminated, status: %d\n", status);
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return;
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@ -1339,7 +1414,9 @@ static int usbtmc_probe(struct usb_interface *intf,
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mutex_init(&data->io_mutex);
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init_waitqueue_head(&data->waitq);
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atomic_set(&data->iin_data_valid, 0);
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atomic_set(&data->srq_asserted, 0);
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INIT_LIST_HEAD(&data->file_list);
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spin_lock_init(&data->dev_lock);
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data->zombie = 0;
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/* Initialize USBTMC bTag and other fields */
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@ -1442,17 +1519,14 @@ static int usbtmc_probe(struct usb_interface *intf,
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static void usbtmc_disconnect(struct usb_interface *intf)
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{
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struct usbtmc_device_data *data;
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struct usbtmc_device_data *data = usb_get_intfdata(intf);
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dev_dbg(&intf->dev, "usbtmc_disconnect called\n");
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data = usb_get_intfdata(intf);
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usb_deregister_dev(intf, &usbtmc_class);
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sysfs_remove_group(&intf->dev.kobj, &capability_attr_grp);
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sysfs_remove_group(&intf->dev.kobj, &data_attr_grp);
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mutex_lock(&data->io_mutex);
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data->zombie = 1;
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wake_up_all(&data->waitq);
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wake_up_interruptible_all(&data->waitq);
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mutex_unlock(&data->io_mutex);
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usbtmc_free_int(data);
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kref_put(&data->kref, usbtmc_delete);
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