From patchwork Mon Jul 30 10:32:57 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mikulas Patocka X-Patchwork-Id: 10548865 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EB6B0157D for ; Mon, 30 Jul 2018 10:33:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CD6F9286E0 for ; Mon, 30 Jul 2018 10:33:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BF68528720; Mon, 30 Jul 2018 10:33:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F1E51286E0 for ; Mon, 30 Jul 2018 10:32:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726810AbeG3MHT (ORCPT ); Mon, 30 Jul 2018 08:07:19 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:48294 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726667AbeG3MHT (ORCPT ); Mon, 30 Jul 2018 08:07:19 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5C12840216FC; Mon, 30 Jul 2018 10:32:57 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (file01.intranet.prod.int.rdu2.redhat.com [10.11.5.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 510142026D76; Mon, 30 Jul 2018 10:32:57 +0000 (UTC) Received: from file01.intranet.prod.int.rdu2.redhat.com (localhost [127.0.0.1]) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4) with ESMTP id w6UAWv6Y011020; Mon, 30 Jul 2018 06:32:57 -0400 Received: from localhost (mpatocka@localhost) by file01.intranet.prod.int.rdu2.redhat.com (8.14.4/8.14.4/Submit) with ESMTP id w6UAWvS1011016; Mon, 30 Jul 2018 06:32:57 -0400 X-Authentication-Warning: file01.intranet.prod.int.rdu2.redhat.com: mpatocka owned process doing -bs Date: Mon, 30 Jul 2018 06:32:57 -0400 (EDT) From: Mikulas Patocka X-X-Sender: mpatocka@file01.intranet.prod.int.rdu2.redhat.com To: Bartlomiej Zolnierkiewicz cc: Dave Airlie , Bernie Thompson , Ladislav Michl , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: [PATCH] udlfb: handle unplug properly Message-ID: User-Agent: Alpine 2.02 (LRH 1266 2009-07-14) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Mon, 30 Jul 2018 10:32:57 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Mon, 30 Jul 2018 10:32:57 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'mpatocka@redhat.com' RCPT:'' Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 --- drivers/video/fbdev/udlfb.c | 141 +++++++++++--------------------------------- include/video/udlfb.h | 3 2 files changed, 37 insertions(+), 107 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Index: linux-4.17.10/drivers/video/fbdev/udlfb.c =================================================================== --- linux-4.17.10.orig/drivers/video/fbdev/udlfb.c 2018-07-27 11:41:12.000000000 +0200 +++ linux-4.17.10/drivers/video/fbdev/udlfb.c 2018-07-27 14:44:47.000000000 +0200 @@ -916,8 +916,6 @@ static int dlfb_ops_open(struct fb_info dlfb->fb_count++; - kref_get(&dlfb->kref); - if (fb_defio && (info->fbdefio == NULL)) { /* enable defio at last moment if not disabled by client */ @@ -940,14 +938,17 @@ static int dlfb_ops_open(struct fb_info return 0; } -/* - * Called when all client interfaces to start transactions have been disabled, - * and all references to our device instance (dlfb_data) are released. - * Every transaction must have a reference, so we know are fully spun down - */ -static void dlfb_free(struct kref *kref) +static void dlfb_ops_destroy(struct fb_info *info) { - struct dlfb_data *dlfb = container_of(kref, struct dlfb_data, kref); + struct dlfb_data *dlfb = info->par; + + if (info->cmap.len != 0) + fb_dealloc_cmap(&info->cmap); + if (info->monspecs.modedb) + fb_destroy_modedb(info->monspecs.modedb); + vfree(info->screen_base); + + fb_destroy_modelist(&info->modelist); while (!list_empty(&dlfb->deferred_free)) { struct dlfb_deferred_free *d = list_entry(dlfb->deferred_free.next, struct dlfb_deferred_free, list); @@ -957,40 +958,13 @@ static void dlfb_free(struct kref *kref) } vfree(dlfb->backing_buffer); kfree(dlfb->edid); + usb_put_dev(dlfb->udev); kfree(dlfb); -} - -static void dlfb_free_framebuffer(struct dlfb_data *dlfb) -{ - struct fb_info *info = dlfb->info; - - if (info) { - unregister_framebuffer(info); - - if (info->cmap.len != 0) - fb_dealloc_cmap(&info->cmap); - if (info->monspecs.modedb) - fb_destroy_modedb(info->monspecs.modedb); - vfree(info->screen_base); - - fb_destroy_modelist(&info->modelist); - - dlfb->info = NULL; - - /* Assume info structure is freed after this point */ - framebuffer_release(info); - } - /* ref taken in probe() as part of registering framebfufer */ - kref_put(&dlfb->kref, dlfb_free); + /* Assume info structure is freed after this point */ + framebuffer_release(info); } -static void dlfb_free_framebuffer_work(struct work_struct *work) -{ - struct dlfb_data *dlfb = container_of(work, struct dlfb_data, - free_framebuffer_work.work); - dlfb_free_framebuffer(dlfb); -} /* * Assumes caller is holding info->lock mutex (for open and release at least) */ @@ -1000,10 +974,6 @@ static int dlfb_ops_release(struct fb_in dlfb->fb_count--; - /* We can't free fb_info here - fbmem will touch it when we return */ - if (dlfb->virtualized && (dlfb->fb_count == 0)) - schedule_delayed_work(&dlfb->free_framebuffer_work, HZ); - if ((dlfb->fb_count == 0) && (info->fbdefio)) { fb_deferred_io_cleanup(info); kfree(info->fbdefio); @@ -1013,8 +983,6 @@ static int dlfb_ops_release(struct fb_in dev_dbg(info->dev, "release, user=%d count=%d\n", user, dlfb->fb_count); - kref_put(&dlfb->kref, dlfb_free); - return 0; } @@ -1172,6 +1140,7 @@ static struct fb_ops dlfb_ops = { .fb_blank = dlfb_ops_blank, .fb_check_var = dlfb_ops_check_var, .fb_set_par = dlfb_ops_set_par, + .fb_destroy = dlfb_ops_destroy, }; @@ -1615,12 +1584,13 @@ success: return true; } -static void dlfb_init_framebuffer_work(struct work_struct *work); - static int dlfb_usb_probe(struct usb_interface *intf, const struct usb_device_id *id) { + int i; + const struct device_attribute *attr; struct dlfb_data *dlfb; + struct fb_info *info; int retval = -ENOMEM; struct usb_device *usbdev = interface_to_usbdev(intf); @@ -1631,10 +1601,9 @@ static int dlfb_usb_probe(struct usb_int goto error; } - kref_init(&dlfb->kref); /* matching kref_put in usb .disconnect fn */ INIT_LIST_HEAD(&dlfb->deferred_free); - dlfb->udev = usbdev; + dlfb->udev = usb_get_dev(usbdev); usb_set_intfdata(intf, dlfb); dev_dbg(&intf->dev, "console enable=%d\n", console); @@ -1657,42 +1626,6 @@ static int dlfb_usb_probe(struct usb_int } - if (!dlfb_alloc_urb_list(dlfb, WRITES_IN_FLIGHT, MAX_TRANSFER)) { - retval = -ENOMEM; - dev_err(&intf->dev, "unable to allocate urb list\n"); - goto error; - } - - kref_get(&dlfb->kref); /* matching kref_put in free_framebuffer_work */ - - /* We don't register a new USB class. Our client interface is dlfbev */ - - /* Workitem keep things fast & simple during USB enumeration */ - INIT_DELAYED_WORK(&dlfb->init_framebuffer_work, - dlfb_init_framebuffer_work); - schedule_delayed_work(&dlfb->init_framebuffer_work, 0); - - return 0; - -error: - if (dlfb) { - - kref_put(&dlfb->kref, dlfb_free); /* last ref from kref_init */ - - /* dev has been deallocated. Do not dereference */ - } - - return retval; -} - -static void dlfb_init_framebuffer_work(struct work_struct *work) -{ - int i, retval; - struct fb_info *info; - const struct device_attribute *attr; - struct dlfb_data *dlfb = container_of(work, struct dlfb_data, - init_framebuffer_work.work); - /* allocates framebuffer driver structure, not framebuffer memory */ info = framebuffer_alloc(0, &dlfb->udev->dev); if (!info) { @@ -1706,17 +1639,22 @@ static void dlfb_init_framebuffer_work(s dlfb->ops = dlfb_ops; info->fbops = &dlfb->ops; + INIT_LIST_HEAD(&info->modelist); + + if (!dlfb_alloc_urb_list(dlfb, WRITES_IN_FLIGHT, MAX_TRANSFER)) { + retval = -ENOMEM; + dev_err(&intf->dev, "unable to allocate urb list\n"); + goto error; + } + + /* We don't register a new USB class. Our client interface is dlfbev */ + retval = fb_alloc_cmap(&info->cmap, 256, 0); if (retval < 0) { dev_err(info->device, "cmap allocation failed: %d\n", retval); goto error; } - INIT_DELAYED_WORK(&dlfb->free_framebuffer_work, - dlfb_free_framebuffer_work); - - INIT_LIST_HEAD(&info->modelist); - retval = dlfb_setup_modes(dlfb, info, NULL, 0); if (retval != 0) { dev_err(info->device, @@ -1760,10 +1698,16 @@ static void dlfb_init_framebuffer_work(s dev_name(info->dev), info->var.xres, info->var.yres, ((dlfb->backing_buffer) ? info->fix.smem_len * 2 : info->fix.smem_len) >> 10); - return; + return 0; error: - dlfb_free_framebuffer(dlfb); + if (dlfb->info) { + dlfb_ops_destroy(dlfb->info); + } else if (dlfb) { + usb_put_dev(dlfb->udev); + kfree(dlfb); + } + return retval; } static void dlfb_usb_disconnect(struct usb_interface *intf) @@ -1791,20 +1735,9 @@ static void dlfb_usb_disconnect(struct u for (i = 0; i < ARRAY_SIZE(fb_device_attrs); i++) device_remove_file(info->dev, &fb_device_attrs[i]); device_remove_bin_file(info->dev, &edid_attr); - unlink_framebuffer(info); } - usb_set_intfdata(intf, NULL); - dlfb->udev = NULL; - - /* if clients still have us open, will be freed on last close */ - if (dlfb->fb_count == 0) - schedule_delayed_work(&dlfb->free_framebuffer_work, 0); - - /* release reference taken by kref_init in probe() */ - kref_put(&dlfb->kref, dlfb_free); - - /* consider dlfb_data freed */ + unregister_framebuffer(info); } static struct usb_driver dlfb_driver = { Index: linux-4.17.10/include/video/udlfb.h =================================================================== --- linux-4.17.10.orig/include/video/udlfb.h 2018-07-27 11:41:12.000000000 +0200 +++ linux-4.17.10/include/video/udlfb.h 2018-07-27 14:20:54.000000000 +0200 @@ -36,12 +36,9 @@ struct dlfb_data { struct usb_device *udev; struct fb_info *info; struct urb_list urbs; - struct kref kref; char *backing_buffer; int fb_count; bool virtualized; /* true when physical usb device not present */ - struct delayed_work init_framebuffer_work; - struct delayed_work free_framebuffer_work; atomic_t usb_active; /* 0 = update virtual buffer, but no usb traffic */ atomic_t lost_pixels; /* 1 = a render op failed. Need screen refresh */ char *edid; /* null until we read edid from hw or get from sysfs */