[PATCH 4.19.y 0/9] Fix scheduling while atomic in dwc3_gadget_ep_dequeue

[John Stultz <john.stultz@linaro.org>]

With recent changes in AOSP, adb is using asynchronous io, which
causes the following crash usually on a reboot:

[  184.278302] BUG: scheduling while atomic: ksoftirqd/0/9/0x00000104
[  184.284617] Modules linked in: wl18xx wlcore snd_soc_hdmi_codec wlcore_sdio tcpci_rt1711h tcpci tcpm typec adv7511 cec dwc3 phy_hi3660_usb3 snd_soc_simple_card snd_soc_a
[  184.316034] Preemption disabled at:
[  184.316072] [<ffffff8008081de4>] __do_softirq+0x64/0x398
[  184.324953] CPU: 0 PID: 9 Comm: ksoftirqd/0 Tainted: G S                4.19.43-00669-g8e4970572c43-dirty #356
[  184.334963] Hardware name: HiKey960 (DT)
[  184.338892] Call trace:
[  184.341352]  dump_backtrace+0x0/0x158
[  184.345025]  show_stack+0x14/0x20
[  184.348355]  dump_stack+0x80/0xa4
[  184.351685]  __schedule_bug+0x6c/0xc0
[  184.355363]  __schedule+0x64c/0x978
[  184.358863]  schedule+0x2c/0x90
[  184.362053]  dwc3_gadget_ep_dequeue+0x274/0x388 [dwc3]
[  184.367210]  usb_ep_dequeue+0x24/0xf8
[  184.370884]  ffs_aio_cancel+0x3c/0x80
[  184.374561]  free_ioctx_users+0x40/0x148
[  184.378500]  percpu_ref_switch_to_atomic_rcu+0x180/0x1c0
[  184.383830]  rcu_process_callbacks+0x24c/0x5d8
[  184.388283]  __do_softirq+0x13c/0x398
[  184.391959]  run_ksoftirqd+0x3c/0x48
[  184.395549]  smpboot_thread_fn+0x220/0x288
[  184.399660]  kthread+0x12c/0x130
[  184.402901]  ret_from_fork+0x10/0x1c


This happens as usb_ep_dequeue can be called in interrupt
context, and dwc3_gadget_ep_dequeue() then calls
wait_event_lock_irq() which can sleep.

Upstream kernels are not affected due to the change
fec9095bdef4 ("dwc3: gadget: remove wait_end_transfer") which
removes the wait_even_lock_irq code. Unfortunately that change
has a number of dependencies, which I'm submitting here.

Also, to match upstream, in this series I've reverted one
change that was backported to -stable, to replace it with the
cherry-picked upstream commit (as the dependencies are now
there)

This issue also affects 4.14,4.9 and I believe 4.4 kernels,
however I don't know how to best backport this functionality
that far back. Help from the maintainers would be very much
appreciated!

Feedback and comments would be welcome!

thanks
-john

Cc: Fei Yang <fei.yang@intel.com>
Cc: Sam Protsenko <semen.protsenko@linaro.org>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: linux-usb@vger.kernel.org
Cc: stable@vger.kernel.org # 4.19.y

Felipe Balbi (7):
  usb: dwc3: gadget: combine unaligned and zero flags
  usb: dwc3: gadget: track number of TRBs per request
  usb: dwc3: gadget: use num_trbs when skipping TRBs on ->dequeue()
  usb: dwc3: gadget: extract dwc3_gadget_ep_skip_trbs()
  usb: dwc3: gadget: introduce cancelled_list
  usb: dwc3: gadget: move requests to cancelled_list
  usb: dwc3: gadget: remove wait_end_transfer

Jack Pham (1):
  usb: dwc3: gadget: Clear req->needs_extra_trb flag on cleanup

John Stultz (1):
  Revert "usb: dwc3: gadget: Clear req->needs_extra_trb flag on cleanup"

 drivers/usb/dwc3/core.h   |  15 ++--
 drivers/usb/dwc3/gadget.c | 158 +++++++++++++-------------------------
 drivers/usb/dwc3/gadget.h |  15 ++++
 3 files changed, 75 insertions(+), 113 deletions(-)

-- 
2.17.1