From d2da8d394147526a28c6d5bb83a72635e7f0a288 Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Thu, 8 Dec 2016 19:55:22 +0800 Subject: usb: gadget: f_fs: Fix possibe deadlock commit b3ce3ce02d146841af012d08506b4071db8ffde3 upstream. When system try to close /dev/usb-ffs/adb/ep0 on one core, at the same time another core try to attach new UDC, which will cause deadlock as below scenario. Thus we should release ffs lock before issuing unregister_gadget_item(). [ 52.642225] c1 ====================================================== [ 52.642228] c1 [ INFO: possible circular locking dependency detected ] [ 52.642236] c1 4.4.6+ #1 Tainted: G W O [ 52.642241] c1 ------------------------------------------------------- [ 52.642245] c1 usb ffs open/2808 is trying to acquire lock: [ 52.642270] c0 (udc_lock){+.+.+.}, at: [] usb_gadget_unregister_driver+0x3c/0xc8 [ 52.642272] c1 but task is already holding lock: [ 52.642283] c0 (ffs_lock){+.+.+.}, at: [] ffs_data_clear+0x30/0x140 [ 52.642285] c1 which lock already depends on the new lock. [ 52.642287] c1 the existing dependency chain (in reverse order) is: [ 52.642295] c0 -> #1 (ffs_lock){+.+.+.}: [ 52.642307] c0 [] __lock_acquire+0x20f0/0x2238 [ 52.642314] c0 [] lock_acquire+0xe4/0x298 [ 52.642322] c0 [] mutex_lock_nested+0x7c/0x3cc [ 52.642328] c0 [] ffs_func_bind+0x504/0x6e8 [ 52.642334] c0 [] usb_add_function+0x84/0x184 [ 52.642340] c0 [] configfs_composite_bind+0x264/0x39c [ 52.642346] c0 [] udc_bind_to_driver+0x58/0x11c [ 52.642352] c0 [] usb_udc_attach_driver+0x90/0xc8 [ 52.642358] c0 [] gadget_dev_desc_UDC_store+0xd4/0x128 [ 52.642369] c0 [] configfs_write_file+0xd0/0x13c [ 52.642376] c0 [] vfs_write+0xb8/0x214 [ 52.642381] c0 [] SyS_write+0x54/0xb0 [ 52.642388] c0 [] el0_svc_naked+0x24/0x28 [ 52.642395] c0 -> #0 (udc_lock){+.+.+.}: [ 52.642401] c0 [] print_circular_bug+0x84/0x2e4 [ 52.642407] c0 [] __lock_acquire+0x2138/0x2238 [ 52.642412] c0 [] lock_acquire+0xe4/0x298 [ 52.642420] c0 [] mutex_lock_nested+0x7c/0x3cc [ 52.642427] c0 [] usb_gadget_unregister_driver+0x3c/0xc8 [ 52.642432] c0 [] unregister_gadget_item+0x28/0x44 [ 52.642439] c0 [] ffs_data_clear+0x138/0x140 [ 52.642444] c0 [] ffs_data_reset+0x20/0x6c [ 52.642450] c0 [] ffs_data_closed+0xac/0x12c [ 52.642454] c0 [] ffs_ep0_release+0x20/0x2c [ 52.642460] c0 [] __fput+0xb0/0x1f4 [ 52.642466] c0 [] ____fput+0x20/0x2c [ 52.642473] c0 [] task_work_run+0xb4/0xe8 [ 52.642482] c0 [] do_exit+0x360/0xb9c [ 52.642487] c0 [] do_group_exit+0x4c/0xb0 [ 52.642494] c0 [] get_signal+0x380/0x89c [ 52.642501] c0 [] do_signal+0x154/0x518 [ 52.642507] c0 [] do_notify_resume+0x70/0x78 [ 52.642512] c0 [] work_pending+0x1c/0x20 [ 52.642514] c1 other info that might help us debug this: [ 52.642517] c1 Possible unsafe locking scenario: [ 52.642518] c1 CPU0 CPU1 [ 52.642520] c1 ---- ---- [ 52.642525] c0 lock(ffs_lock); [ 52.642529] c0 lock(udc_lock); [ 52.642533] c0 lock(ffs_lock); [ 52.642537] c0 lock(udc_lock); [ 52.642539] c1 *** DEADLOCK *** [ 52.642543] c1 1 lock held by usb ffs open/2808: [ 52.642555] c0 #0: (ffs_lock){+.+.+.}, at: [] ffs_data_clear+0x30/0x140 [ 52.642557] c1 stack backtrace: [ 52.642563] c1 CPU: 1 PID: 2808 Comm: usb ffs open Tainted: G [ 52.642565] c1 Hardware name: Spreadtrum SP9860g Board (DT) [ 52.642568] c1 Call trace: [ 52.642573] c1 [] dump_backtrace+0x0/0x170 [ 52.642577] c1 [] show_stack+0x20/0x28 [ 52.642583] c1 [] dump_stack+0xa8/0xe0 [ 52.642587] c1 [] print_circular_bug+0x1fc/0x2e4 [ 52.642591] c1 [] __lock_acquire+0x2138/0x2238 [ 52.642595] c1 [] lock_acquire+0xe4/0x298 [ 52.642599] c1 [] mutex_lock_nested+0x7c/0x3cc [ 52.642604] c1 [] usb_gadget_unregister_driver+0x3c/0xc8 [ 52.642608] c1 [] unregister_gadget_item+0x28/0x44 [ 52.642613] c1 [] ffs_data_clear+0x138/0x140 [ 52.642618] c1 [] ffs_data_reset+0x20/0x6c [ 52.642621] c1 [] ffs_data_closed+0xac/0x12c [ 52.642625] c1 [] ffs_ep0_release+0x20/0x2c [ 52.642629] c1 [] __fput+0xb0/0x1f4 [ 52.642633] c1 [] ____fput+0x20/0x2c [ 52.642636] c1 [] task_work_run+0xb4/0xe8 [ 52.642640] c1 [] do_exit+0x360/0xb9c [ 52.642644] c1 [] do_group_exit+0x4c/0xb0 [ 52.642647] c1 [] get_signal+0x380/0x89c [ 52.642651] c1 [] do_signal+0x154/0x518 [ 52.642656] c1 [] do_notify_resume+0x70/0x78 [ 52.642659] c1 [] work_pending+0x1c/0x20 Acked-by: Michal Nazarewicz Signed-off-by: Baolin Wang Signed-off-by: Felipe Balbi Cc: Jerry Zhang Signed-off-by: Greg Kroah-Hartman diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 04ffd76..f9c9980 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -3688,6 +3688,7 @@ static void ffs_closed(struct ffs_data *ffs) { struct ffs_dev *ffs_obj; struct f_fs_opts *opts; + struct config_item *ci; ENTER(); ffs_dev_lock(); @@ -3711,8 +3712,11 @@ static void ffs_closed(struct ffs_data *ffs) || !atomic_read(&opts->func_inst.group.cg_item.ci_kref.refcount)) goto done; - unregister_gadget_item(ffs_obj->opts-> - func_inst.group.cg_item.ci_parent->ci_parent); + ci = opts->func_inst.group.cg_item.ci_parent->ci_parent; + ffs_dev_unlock(); + + unregister_gadget_item(ci); + return; done: ffs_dev_unlock(); } -- cgit v0.10.2