From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B71FCC31E40 for ; Tue, 6 Aug 2019 19:46:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 886E020880 for ; Tue, 6 Aug 2019 19:46:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726238AbfHFTqH (ORCPT ); Tue, 6 Aug 2019 15:46:07 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:43944 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1725881AbfHFTqH (ORCPT ); Tue, 6 Aug 2019 15:46:07 -0400 Received: (qmail 7047 invoked by uid 2102); 6 Aug 2019 15:46:05 -0400 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 6 Aug 2019 15:46:05 -0400 Date: Tue, 6 Aug 2019 15:46:05 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Greg KH , Mayuresh Kulkarni cc: USB list Subject: [PATCH] usbfs: Add ioctls for runtime power management Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org It has been requested that usbfs should implement runtime power management, instead of forcing the device to remain at full power as long as the device file is open. This patch introduces that new feature. It does so by adding three new usbfs ioctls: USBDEVFS_FORBID_SUSPEND: Prevents the device from going into runtime suspend (and causes a resume if the device is already suspended). USBDEVFS_ALLOW_SUSPEND: Allows the device to go into runtime suspend. Some time may elapse before the device actually is suspended, depending on things like the autosuspend delay. USBDEVFS_WAIT_FOR_RESUME: Blocks until the call is interrupted by a signal or at least one runtime resume has occurred since the most recent ALLOW_SUSPEND ioctl call (which may mean immediately, even if the device is currently suspended). In the latter case, the device is prevented from suspending again just as if FORBID_SUSPEND was called before the ioctl returns. For backward compatibility, when the device file is first opened runtime suspends are forbidden. The userspace program can then allow suspends whenever it wants, and either resume the device directly (by forbidding suspends again) or wait for a resume from some other source (such as a remote wakeup). URBs submitted to a suspended device will fail or will complete with an appropriate error code. This combination of ioctls is sufficient for user programs to have nearly the same degree of control over a device's runtime power behavior as kernel drivers do. Still lacking is documentation for the new ioctls. I intend to add it later, after the existing documentation for the usbfs userspace API is straightened out into a reasonable form. Suggested-by: Mayuresh Kulkarni Signed-off-by: Alan Stern --- [as1905] drivers/usb/core/devio.c | 96 ++++++++++++++++++++++++++++++++++++-- drivers/usb/core/generic.c | 5 + drivers/usb/core/usb.h | 3 + include/uapi/linux/usbdevice_fs.h | 3 + 4 files changed, 102 insertions(+), 5 deletions(-) Index: usb-devel/drivers/usb/core/devio.c =================================================================== --- usb-devel.orig/drivers/usb/core/devio.c +++ usb-devel/drivers/usb/core/devio.c @@ -48,6 +48,9 @@ #define USB_DEVICE_MAX (USB_MAXBUS * 128) #define USB_SG_SIZE 16384 /* split-size for large txs */ +/* Mutual exclusion for ps->list in resume vs. release and remove */ +static DEFINE_MUTEX(usbfs_mutex); + struct usb_dev_state { struct list_head list; /* state list */ struct usb_device *dev; @@ -57,14 +60,17 @@ struct usb_dev_state { struct list_head async_completed; struct list_head memory_list; wait_queue_head_t wait; /* wake up if a request completed */ + wait_queue_head_t wait_for_resume; /* wake up upon runtime resume */ unsigned int discsignr; struct pid *disc_pid; const struct cred *cred; sigval_t disccontext; unsigned long ifclaimed; u32 disabled_bulk_eps; - bool privileges_dropped; unsigned long interface_allowed_mask; + int not_yet_resumed; + bool suspend_allowed; + bool privileges_dropped; }; struct usb_memory { @@ -694,9 +700,7 @@ static void driver_disconnect(struct usb destroy_async_on_interface(ps, ifnum); } -/* The following routines are merely placeholders. There is no way - * to inform a user task about suspend or resumes. - */ +/* We don't care about suspend/resume of claimed interfaces */ static int driver_suspend(struct usb_interface *intf, pm_message_t msg) { return 0; @@ -707,12 +711,32 @@ static int driver_resume(struct usb_inte return 0; } +/* The following routines apply to the entire device, not interfaces */ +void usbfs_notify_suspend(struct usb_device *udev) +{ + /* We don't need to handle this */ +} + +void usbfs_notify_resume(struct usb_device *udev) +{ + struct usb_dev_state *ps; + + /* Protect against simultaneous remove or release */ + mutex_lock(&usbfs_mutex); + list_for_each_entry(ps, &udev->filelist, list) { + WRITE_ONCE(ps->not_yet_resumed, 0); + wake_up_all(&ps->wait_for_resume); + } + mutex_unlock(&usbfs_mutex); +} + struct usb_driver usbfs_driver = { .name = "usbfs", .probe = driver_probe, .disconnect = driver_disconnect, .suspend = driver_suspend, .resume = driver_resume, + .supports_autosuspend = 1, }; static int claimintf(struct usb_dev_state *ps, unsigned int ifnum) @@ -997,9 +1021,12 @@ static int usbdev_open(struct inode *ino INIT_LIST_HEAD(&ps->async_completed); INIT_LIST_HEAD(&ps->memory_list); init_waitqueue_head(&ps->wait); + init_waitqueue_head(&ps->wait_for_resume); ps->disc_pid = get_pid(task_pid(current)); ps->cred = get_current_cred(); smp_wmb(); + + /* Can't race with resume; the device is already active */ list_add_tail(&ps->list, &dev->filelist); file->private_data = ps; usb_unlock_device(dev); @@ -1025,7 +1052,10 @@ static int usbdev_release(struct inode * usb_lock_device(dev); usb_hub_release_all_ports(dev, ps); + /* Protect against simultaneous resume */ + mutex_lock(&usbfs_mutex); list_del_init(&ps->list); + mutex_unlock(&usbfs_mutex); for (ifnum = 0; ps->ifclaimed && ifnum < 8*sizeof(ps->ifclaimed); ifnum++) { @@ -1033,7 +1063,8 @@ static int usbdev_release(struct inode * releaseintf(ps, ifnum); } destroy_all_async(ps); - usb_autosuspend_device(dev); + if (!ps->suspend_allowed) + usb_autosuspend_device(dev); usb_unlock_device(dev); usb_put_dev(dev); put_pid(ps->disc_pid); @@ -2384,6 +2415,47 @@ static int proc_drop_privileges(struct u return 0; } +static int proc_forbid_suspend(struct usb_dev_state *ps) +{ + int ret = 0; + + if (ps->suspend_allowed) { + ret = usb_autoresume_device(ps->dev); + if (ret == 0) + ps->suspend_allowed = false; + else if (ret != -ENODEV) + ret = -EIO; + } + return ret; +} + +static int proc_allow_suspend(struct usb_dev_state *ps) +{ + if (!connected(ps)) + return -ENODEV; + + WRITE_ONCE(ps->not_yet_resumed, 1); + if (!ps->suspend_allowed) { + usb_autosuspend_device(ps->dev); + ps->suspend_allowed = true; + } + return 0; +} + +static int proc_wait_for_resume(struct usb_dev_state *ps) +{ + int ret; + + usb_unlock_device(ps->dev); + ret = wait_event_interruptible(ps->wait_for_resume, + READ_ONCE(ps->not_yet_resumed) == 0); + usb_lock_device(ps->dev); + + if (ret != 0) + return ret; + return proc_forbid_suspend(ps); +} + /* * NOTE: All requests here that have interface numbers as parameters * are assuming that somehow the configuration has been prevented from @@ -2578,6 +2650,15 @@ static long usbdev_do_ioctl(struct file case USBDEVFS_GET_SPEED: ret = ps->dev->speed; break; + case USBDEVFS_FORBID_SUSPEND: + ret = proc_forbid_suspend(ps); + break; + case USBDEVFS_ALLOW_SUSPEND: + ret = proc_allow_suspend(ps); + break; + case USBDEVFS_WAIT_FOR_RESUME: + ret = proc_wait_for_resume(ps); + break; } /* Handle variable-length commands */ @@ -2651,15 +2732,20 @@ static void usbdev_remove(struct usb_dev { struct usb_dev_state *ps; + /* Protect against simultaneous resume */ + mutex_lock(&usbfs_mutex); while (!list_empty(&udev->filelist)) { ps = list_entry(udev->filelist.next, struct usb_dev_state, list); destroy_all_async(ps); wake_up_all(&ps->wait); + WRITE_ONCE(ps->not_yet_resumed, 0); + wake_up_all(&ps->wait_for_resume); list_del_init(&ps->list); if (ps->discsignr) kill_pid_usb_asyncio(ps->discsignr, EPIPE, ps->disccontext, ps->disc_pid, ps->cred); } + mutex_unlock(&usbfs_mutex); } static int usbdev_notify(struct notifier_block *self, Index: usb-devel/drivers/usb/core/generic.c =================================================================== --- usb-devel.orig/drivers/usb/core/generic.c +++ usb-devel/drivers/usb/core/generic.c @@ -257,6 +257,8 @@ static int generic_suspend(struct usb_de else rc = usb_port_suspend(udev, msg); + if (rc == 0) + usbfs_notify_suspend(udev); return rc; } @@ -273,6 +275,9 @@ static int generic_resume(struct usb_dev rc = hcd_bus_resume(udev, msg); else rc = usb_port_resume(udev, msg); + + if (rc == 0) + usbfs_notify_resume(udev); return rc; } Index: usb-devel/drivers/usb/core/usb.h =================================================================== --- usb-devel.orig/drivers/usb/core/usb.h +++ usb-devel/drivers/usb/core/usb.h @@ -95,6 +95,9 @@ extern int usb_runtime_idle(struct devic extern int usb_enable_usb2_hardware_lpm(struct usb_device *udev); extern int usb_disable_usb2_hardware_lpm(struct usb_device *udev); +extern void usbfs_notify_suspend(struct usb_device *udev); +extern void usbfs_notify_resume(struct usb_device *udev); + #else static inline int usb_port_suspend(struct usb_device *udev, pm_message_t msg) Index: usb-devel/include/uapi/linux/usbdevice_fs.h =================================================================== --- usb-devel.orig/include/uapi/linux/usbdevice_fs.h +++ usb-devel/include/uapi/linux/usbdevice_fs.h @@ -223,5 +223,8 @@ struct usbdevfs_streams { * extending size of the data returned. */ #define USBDEVFS_CONNINFO_EX(len) _IOC(_IOC_READ, 'U', 32, len) +#define USBDEVFS_FORBID_SUSPEND _IO('U', 33) +#define USBDEVFS_ALLOW_SUSPEND _IO('U', 34) +#define USBDEVFS_WAIT_FOR_RESUME _IO('U', 35) #endif /* _UAPI_LINUX_USBDEVICE_FS_H */