b78e84d132
simultaneously detaching kernel drivers on the same USB device we can get stuck in the "usb_wait_pending_ref_locked()" function because the conditions needed for allowing detach are not met. The "destroy_dev()" function waits for all system calls involving the given character device to return. Character device system calls may lock the USB enumeration lock, which is also held when "destroy_dev()" is called. This can sometimes lead to a deadlock not noticed by WITNESS. The current solution is to ensure the calling thread is the only one holding the USB enumeration lock and prevent other threads from getting refs while a USB device detach is ongoing. This turned out not to be sufficient. To solve this deadlock we could use "destroy_dev_sched()" to schedule the device destruction in the background, but then we don't know when it is safe to free() the private data of the character device. Instead a callback function is executed by the USB explore process to kill off any leftover USB character devices synchronously after the USB device explore code is finished and the USB enumeration lock is no longer locked. This makes porting easier and also ensures us that character devices must eventually go away after a USB device detach. While at it ensure that "flag_iserror" is only written when "priv_mtx" is locked, which is protecting it. MFC after: 5 days
128 lines
4.1 KiB
C
128 lines
4.1 KiB
C
/* $FreeBSD$ */
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/*-
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* Copyright (c) 2008 Hans Petter Selasky. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef _USB_BUS_H_
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#define _USB_BUS_H_
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struct usb_fs_privdata;
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/*
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* The following structure defines the USB explore message sent to the USB
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* explore process.
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*/
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struct usb_bus_msg {
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struct usb_proc_msg hdr;
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struct usb_bus *bus;
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};
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/*
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* The following structure defines the USB statistics structure.
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*/
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struct usb_bus_stat {
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uint32_t uds_requests[4];
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};
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/*
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* The following structure defines an USB BUS. There is one USB BUS
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* for every Host or Device controller.
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*/
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struct usb_bus {
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struct usb_bus_stat stats_err;
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struct usb_bus_stat stats_ok;
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#if USB_HAVE_ROOT_MOUNT_HOLD
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struct root_hold_token *bus_roothold;
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#endif
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#if USB_HAVE_PER_BUS_PROCESS
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#define USB_BUS_GIANT_PROC(bus) (&(bus)->giant_callback_proc)
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#define USB_BUS_NON_GIANT_PROC(bus) (&(bus)->non_giant_callback_proc)
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#define USB_BUS_EXPLORE_PROC(bus) (&(bus)->explore_proc)
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#define USB_BUS_CONTROL_XFER_PROC(bus) (&(bus)->control_xfer_proc)
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/*
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* There are two callback processes. One for Giant locked
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* callbacks. One for non-Giant locked callbacks. This should
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* avoid congestion and reduce response time in most cases.
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*/
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struct usb_process giant_callback_proc;
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struct usb_process non_giant_callback_proc;
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/* Explore process */
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struct usb_process explore_proc;
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/* Control request process */
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struct usb_process control_xfer_proc;
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#endif
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struct usb_bus_msg explore_msg[2];
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struct usb_bus_msg detach_msg[2];
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struct usb_bus_msg attach_msg[2];
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struct usb_bus_msg suspend_msg[2];
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struct usb_bus_msg resume_msg[2];
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struct usb_bus_msg reset_msg[2];
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struct usb_bus_msg shutdown_msg[2];
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#if USB_HAVE_UGEN
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struct usb_bus_msg cleanup_msg[2];
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LIST_HEAD(,usb_fs_privdata) pd_cleanup_list;
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#endif
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/*
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* This mutex protects the USB hardware:
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*/
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struct mtx bus_mtx;
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struct mtx bus_spin_lock;
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struct usb_xfer_queue intr_q;
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struct usb_callout power_wdog; /* power management */
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device_t parent;
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device_t bdev; /* filled by HC driver */
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#if USB_HAVE_BUSDMA
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struct usb_dma_parent_tag dma_parent_tag[1];
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struct usb_dma_tag dma_tags[USB_BUS_DMA_TAG_MAX];
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#endif
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const struct usb_bus_methods *methods; /* filled by HC driver */
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struct usb_device **devices;
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struct ifnet *ifp; /* only for USB Packet Filter */
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usb_power_mask_t hw_power_state; /* see USB_HW_POWER_XXX */
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usb_size_t uframe_usage[USB_HS_MICRO_FRAMES_MAX];
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uint16_t isoc_time_last; /* in milliseconds */
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uint8_t alloc_failed; /* Set if memory allocation failed. */
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uint8_t driver_added_refcount; /* Current driver generation count */
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enum usb_revision usbrev; /* USB revision. See "USB_REV_XXX". */
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uint8_t devices_max; /* maximum number of USB devices */
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uint8_t do_probe; /* set if USB should be re-probed */
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uint8_t no_explore; /* don't explore USB ports */
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uint8_t dma_bits; /* number of DMA address lines */
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};
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#endif /* _USB_BUS_H_ */
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