mirror of https://gitee.com/openkylin/linux.git
udlfb: handle unplug properly
The udlfb driver maintained an open count and cleaned up itself when the count reached zero. But the console is also counted in the reference count - so, if the user unplugged the device, the open count would not drop to zero and the driver stayed loaded with console attached. If the user re-plugged the adapter, it would create a device /dev/fb1, show green screen and the access to the console would be lost. The framebuffer subsystem has reference counting on its own - in order to fix the unplug bug, we rely the framebuffer reference counting. When the user unplugs the adapter, we call unregister_framebuffer unconditionally. unregister_framebuffer will unbind the console, wait until all users stop using the framebuffer and then call the fb_destroy method. The fb_destroy cleans up the USB driver. This patch makes the following changes: * Drop dlfb->kref and rely on implicit framebuffer reference counting instead. * dlfb_usb_disconnect calls unregister_framebuffer, the rest of driver cleanup is done in the function dlfb_ops_destroy. dlfb_ops_destroy will be called by the framebuffer subsystem when no processes have the framebuffer open or mapped. * We don't use workqueue during initialization, but initialize directly from dlfb_usb_probe. The workqueue could race with dlfb_usb_disconnect and this racing would produce various kinds of memory corruption. * We use usb_get_dev and usb_put_dev to make sure that the USB subsystem doesn't free the device under us. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> cc: Dave Airlie <airlied@redhat.com> Cc: Bernie Thompson <bernie@plugable.com>, Cc: Ladislav Michl <ladis@linux-mips.org> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
This commit is contained in:
Mikulas Patocka
Bartlomiej Zolnierkiewicz
parent
ad4366ad48
commit
68a958a915
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@ -916,8 +916,6 @@ static int dlfb_ops_open(struct fb_info *info, int user)
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dlfb->fb_count++;
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kref_get(&dlfb->kref);
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if (fb_defio && (info->fbdefio == NULL)) {
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/* enable defio at last moment if not disabled by client */
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@ -940,14 +938,17 @@ static int dlfb_ops_open(struct fb_info *info, int user)
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return 0;
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}
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/*
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* Called when all client interfaces to start transactions have been disabled,
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* and all references to our device instance (dlfb_data) are released.
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* Every transaction must have a reference, so we know are fully spun down
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*/
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static void dlfb_free(struct kref *kref)
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static void dlfb_ops_destroy(struct fb_info *info)
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{
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struct dlfb_data *dlfb = container_of(kref, struct dlfb_data, kref);
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struct dlfb_data *dlfb = info->par;
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if (info->cmap.len != 0)
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fb_dealloc_cmap(&info->cmap);
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if (info->monspecs.modedb)
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fb_destroy_modedb(info->monspecs.modedb);
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vfree(info->screen_base);
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fb_destroy_modelist(&info->modelist);
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while (!list_empty(&dlfb->deferred_free)) {
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struct dlfb_deferred_free *d = list_entry(dlfb->deferred_free.next, struct dlfb_deferred_free, list);
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@ -957,40 +958,13 @@ static void dlfb_free(struct kref *kref)
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}
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vfree(dlfb->backing_buffer);
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kfree(dlfb->edid);
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usb_put_dev(dlfb->udev);
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kfree(dlfb);
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/* Assume info structure is freed after this point */
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framebuffer_release(info);
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}
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static void dlfb_free_framebuffer(struct dlfb_data *dlfb)
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{
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struct fb_info *info = dlfb->info;
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if (info) {
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unregister_framebuffer(info);
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if (info->cmap.len != 0)
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fb_dealloc_cmap(&info->cmap);
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if (info->monspecs.modedb)
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fb_destroy_modedb(info->monspecs.modedb);
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vfree(info->screen_base);
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fb_destroy_modelist(&info->modelist);
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dlfb->info = NULL;
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/* Assume info structure is freed after this point */
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framebuffer_release(info);
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}
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/* ref taken in probe() as part of registering framebfufer */
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kref_put(&dlfb->kref, dlfb_free);
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}
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static void dlfb_free_framebuffer_work(struct work_struct *work)
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{
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struct dlfb_data *dlfb = container_of(work, struct dlfb_data,
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free_framebuffer_work.work);
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dlfb_free_framebuffer(dlfb);
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}
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/*
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* Assumes caller is holding info->lock mutex (for open and release at least)
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*/
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@ -1000,10 +974,6 @@ static int dlfb_ops_release(struct fb_info *info, int user)
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dlfb->fb_count--;
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/* We can't free fb_info here - fbmem will touch it when we return */
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if (dlfb->virtualized && (dlfb->fb_count == 0))
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schedule_delayed_work(&dlfb->free_framebuffer_work, HZ);
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if ((dlfb->fb_count == 0) && (info->fbdefio)) {
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fb_deferred_io_cleanup(info);
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kfree(info->fbdefio);
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@ -1013,8 +983,6 @@ static int dlfb_ops_release(struct fb_info *info, int user)
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dev_dbg(info->dev, "release, user=%d count=%d\n", user, dlfb->fb_count);
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kref_put(&dlfb->kref, dlfb_free);
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return 0;
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}
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@ -1172,6 +1140,7 @@ static struct fb_ops dlfb_ops = {
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.fb_blank = dlfb_ops_blank,
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.fb_check_var = dlfb_ops_check_var,
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.fb_set_par = dlfb_ops_set_par,
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.fb_destroy = dlfb_ops_destroy,
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};
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@ -1615,12 +1584,13 @@ static int dlfb_parse_vendor_descriptor(struct dlfb_data *dlfb,
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return true;
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}
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static void dlfb_init_framebuffer_work(struct work_struct *work);
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static int dlfb_usb_probe(struct usb_interface *intf,
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const struct usb_device_id *id)
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{
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int i;
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const struct device_attribute *attr;
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struct dlfb_data *dlfb;
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struct fb_info *info;
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int retval = -ENOMEM;
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struct usb_device *usbdev = interface_to_usbdev(intf);
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@ -1631,10 +1601,9 @@ static int dlfb_usb_probe(struct usb_interface *intf,
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goto error;
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}
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kref_init(&dlfb->kref); /* matching kref_put in usb .disconnect fn */
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INIT_LIST_HEAD(&dlfb->deferred_free);
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dlfb->udev = usbdev;
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dlfb->udev = usb_get_dev(usbdev);
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usb_set_intfdata(intf, dlfb);
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dev_dbg(&intf->dev, "console enable=%d\n", console);
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@ -1657,42 +1626,6 @@ static int dlfb_usb_probe(struct usb_interface *intf,
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}
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if (!dlfb_alloc_urb_list(dlfb, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
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retval = -ENOMEM;
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dev_err(&intf->dev, "unable to allocate urb list\n");
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goto error;
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}
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kref_get(&dlfb->kref); /* matching kref_put in free_framebuffer_work */
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/* We don't register a new USB class. Our client interface is dlfbev */
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/* Workitem keep things fast & simple during USB enumeration */
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INIT_DELAYED_WORK(&dlfb->init_framebuffer_work,
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dlfb_init_framebuffer_work);
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schedule_delayed_work(&dlfb->init_framebuffer_work, 0);
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return 0;
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error:
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if (dlfb) {
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kref_put(&dlfb->kref, dlfb_free); /* last ref from kref_init */
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/* dev has been deallocated. Do not dereference */
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}
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return retval;
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}
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static void dlfb_init_framebuffer_work(struct work_struct *work)
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{
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int i, retval;
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struct fb_info *info;
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const struct device_attribute *attr;
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struct dlfb_data *dlfb = container_of(work, struct dlfb_data,
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init_framebuffer_work.work);
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/* allocates framebuffer driver structure, not framebuffer memory */
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info = framebuffer_alloc(0, &dlfb->udev->dev);
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if (!info) {
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@ -1706,17 +1639,22 @@ static void dlfb_init_framebuffer_work(struct work_struct *work)
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dlfb->ops = dlfb_ops;
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info->fbops = &dlfb->ops;
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INIT_LIST_HEAD(&info->modelist);
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if (!dlfb_alloc_urb_list(dlfb, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
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retval = -ENOMEM;
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dev_err(&intf->dev, "unable to allocate urb list\n");
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goto error;
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}
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/* We don't register a new USB class. Our client interface is dlfbev */
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retval = fb_alloc_cmap(&info->cmap, 256, 0);
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if (retval < 0) {
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dev_err(info->device, "cmap allocation failed: %d\n", retval);
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goto error;
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}
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INIT_DELAYED_WORK(&dlfb->free_framebuffer_work,
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dlfb_free_framebuffer_work);
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INIT_LIST_HEAD(&info->modelist);
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retval = dlfb_setup_modes(dlfb, info, NULL, 0);
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if (retval != 0) {
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dev_err(info->device,
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@ -1760,10 +1698,16 @@ static void dlfb_init_framebuffer_work(struct work_struct *work)
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dev_name(info->dev), info->var.xres, info->var.yres,
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((dlfb->backing_buffer) ?
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info->fix.smem_len * 2 : info->fix.smem_len) >> 10);
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return;
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return 0;
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error:
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dlfb_free_framebuffer(dlfb);
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if (dlfb->info) {
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dlfb_ops_destroy(dlfb->info);
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} else if (dlfb) {
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usb_put_dev(dlfb->udev);
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kfree(dlfb);
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}
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return retval;
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}
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static void dlfb_usb_disconnect(struct usb_interface *intf)
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@ -1791,20 +1735,9 @@ static void dlfb_usb_disconnect(struct usb_interface *intf)
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for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++)
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device_remove_file(info->dev, &fb_device_attrs[i]);
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device_remove_bin_file(info->dev, &edid_attr);
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unlink_framebuffer(info);
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}
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usb_set_intfdata(intf, NULL);
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dlfb->udev = NULL;
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/* if clients still have us open, will be freed on last close */
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if (dlfb->fb_count == 0)
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schedule_delayed_work(&dlfb->free_framebuffer_work, 0);
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/* release reference taken by kref_init in probe() */
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kref_put(&dlfb->kref, dlfb_free);
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/* consider dlfb_data freed */
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unregister_framebuffer(info);
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}
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static struct usb_driver dlfb_driver = {
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@ -36,12 +36,9 @@ struct dlfb_data {
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struct usb_device *udev;
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struct fb_info *info;
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struct urb_list urbs;
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struct kref kref;
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char *backing_buffer;
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int fb_count;
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bool virtualized; /* true when physical usb device not present */
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struct delayed_work init_framebuffer_work;
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struct delayed_work free_framebuffer_work;
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atomic_t usb_active; /* 0 = update virtual buffer, but no usb traffic */
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atomic_t lost_pixels; /* 1 = a render op failed. Need screen refresh */
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char *edid; /* null until we read edid from hw or get from sysfs */
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