Basically when plugging in various cables in different orders, I'm occasionally seeing the following BUG splat:
[ 86.215403] BUG: scheduling while atomic: kworker/u16:2/53/0x00000002 [ 86.219164] usb 1-1: USB disconnect, device number 9 [ 86.226845] Preemption disabled at:[ 86.230218] [<ffffff8008673558>] dwc2_conn_id_status_change+0x120/0x250 [ 86.236894] CPU: 0 PID: 53 Comm: kworker/u16:2 Tainted: G W 4.9.0-rc8-00051-gd5a7979-dirty #1702 [ 86.246836] Hardware name: HiKey Development Board (DT) [ 86.252100] Workqueue: dwc2 dwc2_conn_id_status_change [ 86.257279] Call trace: [ 86.259771] [<ffffff8008087c28>] dump_backtrace+0x0/0x1a0 [ 86.265210] [<ffffff8008087ddc>] show_stack+0x14/0x20 [ 86.270308] [<ffffff80084343f0>] dump_stack+0x90/0xb0 [ 86.275401] [<ffffff80080d8d94>] __schedule_bug+0x6c/0xb8 [ 86.280841] [<ffffff8008a07220>] __schedule+0x4f8/0x5b0 [ 86.286099] [<ffffff8008a073e8>] schedule+0x38/0xa0 [ 86.291017] [<ffffff8008a0a6cc>] schedule_hrtimeout_range_clock+0x8c/0xf0 [ 86.297846] [<ffffff8008a0a740>] schedule_hrtimeout_range+0x10/0x18 [ 86.304150] [<ffffff8008a0a4a0>] usleep_range+0x50/0x58 [ 86.309418] [<ffffff800866d8dc>] dwc2_wait_for_mode.isra.4+0x54/0xd0 [ 86.315815] [<ffffff800866f058>] dwc2_core_reset+0xe0/0x168 [ 86.321431] [<ffffff800867e364>] dwc2_hsotg_core_init_disconnected+0x2c/0x310 [ 86.328602] [<ffffff8008673568>] dwc2_conn_id_status_change+0x130/0x250 [ 86.335254] [<ffffff80080ccd48>] process_one_work+0x118/0x370 [ 86.341035] [<ffffff80080ccfe8>] worker_thread+0x48/0x498 [ 86.346473] [<ffffff80080d2eb0>] kthread+0xd0/0xe8 [ 86.351299] [<ffffff8008082e80>] ret_from_fork+0x10/0x50 This seems to be caused by the dwc2_wait_for_mode() calling usleep_range() while the hstog->lock spinlock is held, since we take that before calling dwc2_hsotg_core_init_disconnected(). This patch avoids the issue by adding an extra argument to dwc2_core_reset(), as suggested by John Youn, which allows us to skip the waiting, which should be unnecessary when calling from dwc2_hsotg_core_init_disconnected(). Cc: Wei Xu <xuw...@hisilicon.com> Cc: Guodong Xu <guodong...@linaro.org> Cc: Amit Pundir <amit.pun...@linaro.org> Cc: Rob Herring <robh...@kernel.org> Cc: John Youn <johny...@synopsys.com> Cc: Douglas Anderson <diand...@chromium.org> Cc: Chen Yu <cheny...@huawei.com> Cc: Kishon Vijay Abraham I <kis...@ti.com> Cc: Felipe Balbi <felipe.ba...@linux.intel.com> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> Cc: linux-...@vger.kernel.org Signed-off-by: John Stultz <john.stu...@linaro.org> --- drivers/usb/dwc2/core.c | 6 +++--- drivers/usb/dwc2/core.h | 2 +- drivers/usb/dwc2/gadget.c | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c index 4c0fa0b..2e83545 100644 --- a/drivers/usb/dwc2/core.c +++ b/drivers/usb/dwc2/core.c @@ -313,7 +313,7 @@ static bool dwc2_iddig_filter_enabled(struct dwc2_hsotg *hsotg) * Do core a soft reset of the core. Be careful with this because it * resets all the internal state machines of the core. */ -int dwc2_core_reset(struct dwc2_hsotg *hsotg) +int dwc2_core_reset(struct dwc2_hsotg *hsotg, bool skip_wait) { u32 greset; int count = 0; @@ -369,7 +369,7 @@ int dwc2_core_reset(struct dwc2_hsotg *hsotg) } } while (!(greset & GRSTCTL_AHBIDLE)); - if (wait_for_host_mode) + if (wait_for_host_mode && !skip_wait) dwc2_wait_for_mode(hsotg, true); return 0; @@ -500,7 +500,7 @@ int dwc2_core_reset_and_force_dr_mode(struct dwc2_hsotg *hsotg) { int retval; - retval = dwc2_core_reset(hsotg); + retval = dwc2_core_reset(hsotg, false); if (retval) return retval; diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h index 2a21a04..963ea1b 100644 --- a/drivers/usb/dwc2/core.h +++ b/drivers/usb/dwc2/core.h @@ -1020,7 +1020,7 @@ enum dwc2_halt_status { * The following functions support initialization of the core driver component * and the DWC_otg controller */ -extern int dwc2_core_reset(struct dwc2_hsotg *hsotg); +extern int dwc2_core_reset(struct dwc2_hsotg *hsotg, bool skip_wait); extern int dwc2_core_reset_and_force_dr_mode(struct dwc2_hsotg *hsotg); extern int dwc2_enter_hibernation(struct dwc2_hsotg *hsotg); extern int dwc2_exit_hibernation(struct dwc2_hsotg *hsotg, bool restore); diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c index 24fbebc..0bda799 100644 --- a/drivers/usb/dwc2/gadget.c +++ b/drivers/usb/dwc2/gadget.c @@ -2521,7 +2521,7 @@ void dwc2_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg, kill_all_requests(hsotg, hsotg->eps_out[0], -ECONNRESET); if (!is_usb_reset) - if (dwc2_core_reset(hsotg)) + if (dwc2_core_reset(hsotg, true)) return; /* -- 2.7.4