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Alan Stern 63aea0dbab USB: xhci: fix lock-inversion problem
With threaded interrupts, bottom-half handlers are called with
interrupts enabled.  Therefore they can't safely use spin_lock(); they
have to use spin_lock_irqsave().  Lockdep warns about a violation
occurring in xhci_irq():

=========================================================
[ INFO: possible irq lock inversion dependency detected ]
4.11.0-rc8-dbg+ #1 Not tainted
---------------------------------------------------------
swapper/7/0 just changed the state of lock:
 (&(&ehci->lock)->rlock){-.-...}, at: [<ffffffffa0130a69>]
ehci_hrtimer_func+0x29/0xc0 [ehci_hcd]
but this lock took another, HARDIRQ-unsafe lock in the past:
 (hcd_urb_list_lock){+.....}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(hcd_urb_list_lock);
                               local_irq_disable();
                               lock(&(&ehci->lock)->rlock);
                               lock(hcd_urb_list_lock);
  <Interrupt>
    lock(&(&ehci->lock)->rlock);
 *** DEADLOCK ***

no locks held by swapper/7/0.
the shortest dependencies between 2nd lock and 1st lock:
 -> (hcd_urb_list_lock){+.....} ops: 252 {
    HARDIRQ-ON-W at:
                      __lock_acquire+0x602/0x1280
                      lock_acquire+0xd5/0x1c0
                      _raw_spin_lock+0x2f/0x40
                      usb_hcd_unlink_urb_from_ep+0x1b/0x60 [usbcore]
                      xhci_giveback_urb_in_irq.isra.45+0x70/0x1b0 [xhci_hcd]
                      finish_td.constprop.60+0x1d8/0x2e0 [xhci_hcd]
                      xhci_irq+0xdd6/0x1fa0 [xhci_hcd]
                      usb_hcd_irq+0x26/0x40 [usbcore]
                      irq_forced_thread_fn+0x2f/0x70
                      irq_thread+0x149/0x1d0
                      kthread+0x113/0x150
                      ret_from_fork+0x2e/0x40

This patch fixes the problem.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: Bart Van Assche <bart.vanassche@sandisk.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-05-18 15:19:42 +02:00
arch Merge branch 'for-linus-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2017-05-13 10:20:02 -07:00
block Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm 2017-05-12 15:43:10 -07:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto treewide: use kv[mz]alloc* rather than opencoded variants 2017-05-08 17:15:13 -07:00
Documentation doc-rst: fixed kernel-doc directives in usb/typec.rst 2017-05-17 11:52:44 +02:00
drivers USB: xhci: fix lock-inversion problem 2017-05-18 15:19:42 +02:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs This pull request contains updates for both UBI and UBIFS: 2017-05-13 10:23:12 -07:00
include usb: host: xhci-ring: don't need to clear interrupt pending for MSI enabled hcd 2017-05-18 15:19:41 +02:00
init Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-10 10:30:46 -07:00
ipc mm: introduce kv[mz]alloc helpers 2017-05-08 17:15:12 -07:00
kernel gcov: support GCC 7.1 2017-05-12 15:57:15 -07:00
lib dmaengine updates for 4.12-rc1 2017-05-09 15:40:28 -07:00
mm mm: vmscan: scan until it finds eligible pages 2017-05-12 15:57:16 -07:00
net Another RDMA update from Chuck Lever, and a bunch of miscellaneous 2017-05-10 13:29:23 -07:00
samples char/misc patches for 4.12-rc1 2017-05-04 19:15:35 -07:00
scripts Kbuild UAPI header export updates for v4.12 2017-05-10 20:45:36 -07:00
security Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
sound sound fixes for 4.12-rc1 2017-05-12 12:10:38 -07:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-12 10:45:36 -07:00
usr initramfs: provide a way to ignore image provided by bootloader 2017-05-08 17:15:12 -07:00
virt Second round of KVM/ARM Changes for v4.12. 2017-05-09 12:51:49 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING [PATCH] update FSF address in COPYING 2005-09-10 10:06:29 -07:00
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig kbuild: migrate all arch to the kconfig mainmenu upgrade 2010-09-19 22:54:11 -04:00
MAINTAINERS Tigran has moved 2017-05-12 15:57:15 -07:00
Makefile Linux 4.12-rc1 2017-05-13 13:19:49 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.