Dominik Bozek b86b8eb6fe usb: cdc_acm: prevent race at write to acm while system resumes ... ACM driver may accept data to transmit while system is not fully resumed. In this case ACM driver buffers data and prepare URBs on usb anchor list. There is a little chance that two tasks put a char and initiate acm_tty_flush_chars(). In such a case, driver will put one URB twice on usb anchor list. This patch also reset length of data before resue of a buffer. This not only prevent sending rubbish, but also lower risc of race. Without this patch we hit following kernel panic in one of our stabilty/stress tests. [ 46.884442] *list_add double add*: new=ffff9b2ab7289330, prev=ffff9b2ab7289330, next=ffff9b2ab81e28e0. [ 46.884476] Modules linked in: hci_uart btbcm bluetooth rfkill_gpio igb_avb(O) cfg80211 snd_soc_sst_bxt_tdf8532 snd_soc_skl snd_soc_skl_ipc snd_soc_sst_ipc snd_soc_sst_dsp snd_soc_sst_acpi snd_soc_sst_match snd_hda_ext_core snd_hda_core trusty_timer trusty_wall trusty_log trusty_virtio trusty_ipc trusty_mem trusty_irq trusty virtio_ring virtio intel_ipu4_mmu_bxtB0 lib2600_mod_bxtB0 intel_ipu4_isys_mod_bxtB0 lib2600psys_mod_bxtB0 intel_ipu4_psys_mod_bxtB0 intel_ipu4_mod_bxtB0 intel_ipu4_wrapper_bxtB0 intel_ipu4_acpi videobuf2_dma_contig as3638 dw9714 lm3643 crlmodule smiapp smiapp_pll [ 46.884480] CPU: 1 PID: 33 Comm: kworker/u8:1 Tainted: G U W O 4.9.56-quilt-2e5dc0ac-g618ed69ced6e-dirty #4 [ 46.884489] Workqueue: events_unbound flush_to_ldisc [ 46.884494] ffffb98ac012bb08 ffffffffad3e82e5 ffffb98ac012bb58 0000000000000000 [ 46.884497] ffffb98ac012bb48 ffffffffad0a23d1 00000024ad6374dd ffff9b2ab7289330 [ 46.884500] ffff9b2ab81e28e0 ffff9b2ab7289330 0000000000000002 0000000000000000 [ 46.884501] Call Trace: [ 46.884507] [<ffffffffad3e82e5>] dump_stack+0x67/0x92 [ 46.884511] [<ffffffffad0a23d1>] __warn+0xd1/0xf0 [ 46.884513] [<ffffffffad0a244f>] warn_slowpath_fmt+0x5f/0x80 [ 46.884516] [<ffffffffad407443>] __list_add+0xb3/0xc0 [ 46.884521] [<ffffffffad71133c>] *usb_anchor_urb*+0x4c/0xa0 [ 46.884524] [<ffffffffad782c6f>] *acm_tty_flush_chars*+0x8f/0xb0 [ 46.884527] [<ffffffffad782cd1>] *acm_tty_put_char*+0x41/0x100 [ 46.884530] [<ffffffffad4ced34>] tty_put_char+0x24/0x40 [ 46.884533] [<ffffffffad4d3bf5>] do_output_char+0xa5/0x200 [ 46.884535] [<ffffffffad4d3e98>] __process_echoes+0x148/0x290 [ 46.884538] [<ffffffffad4d654c>] n_tty_receive_buf_common+0x57c/0xb00 [ 46.884541] [<ffffffffad4d6ae4>] n_tty_receive_buf2+0x14/0x20 [ 46.884543] [<ffffffffad4d9662>] tty_ldisc_receive_buf+0x22/0x50 [ 46.884545] [<ffffffffad4d9c05>] flush_to_ldisc+0xc5/0xe0 [ 46.884549] [<ffffffffad0bcfe8>] process_one_work+0x148/0x440 [ 46.884551] [<ffffffffad0bdc19>] worker_thread+0x69/0x4a0 [ 46.884554] [<ffffffffad0bdbb0>] ? max_active_store+0x80/0x80 [ 46.884556] [<ffffffffad0c2e10>] kthread+0x110/0x130 [ 46.884559] [<ffffffffad0c2d00>] ? kthread_park+0x60/0x60 [ 46.884563] [<ffffffffadad9917>] ret_from_fork+0x27/0x40 [ 46.884566] ---[ end trace 3bd599058b8a9eb3 ]--- Signed-off-by: Dominik Bozek <dominikx.bozek@intel.com> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Acked-by: Oliver Neukum <oneukum@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2018-02-16 07:52:55 +01:00
..
cdc-acm.c	usb: cdc_acm: prevent race at write to acm while system resumes	2018-02-16 07:52:55 +01:00
cdc-acm.h	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
cdc-wdm.c	vfs: do bulk POLL* -> EPOLL* replacement	2018-02-11 14:34:03 -08:00
Kconfig	usb: fix some references for /proc/bus/usb	2017-04-18 16:54:19 +02:00
Makefile	USB: add SPDX identifiers to all remaining Makefiles	2017-11-07 15:53:48 +01:00
usblp.c	vfs: do bulk POLL* -> EPOLL* replacement	2018-02-11 14:34:03 -08:00
usbtmc.c	vfs: do bulk POLL* -> EPOLL* replacement	2018-02-11 14:34:03 -08:00