USB: cdc-acm: untangle a circular dependency between callback and softint
We have a cycle of callbacks scheduling works which submit
URBs with thos callbacks. This needs to be blocked, stopped
and unblocked to untangle the circle.
The issue leads to faults like:
[ 55.068392] Unable to handle kernel paging request at virtual address 6b6b6c03
[ 55.075624] pgd = be866494
[ 55.078335] [6b6b6c03] *pgd=00000000
[ 55.081924] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
[ 55.087238] Modules linked in: ppp_async crc_ccitt ppp_generic slhc
xt_TCPMSS xt_tcpmss xt_hl nf_log_ipv6 nf_log_ipv4 nf_log_common
xt_policy xt_limit xt_conntrack xt_tcpudp xt_pkttype ip6table_mangle
iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4
iptable_mangle ip6table_filter ip6_tables iptable_filter ip_tables
des_generic md5 sch_fq_codel cdc_mbim cdc_wdm cdc_ncm usbnet mii
cdc_acm usb_storage ip_tunnel xfrm_user xfrm6_tunnel tunnel6
xfrm4_tunnel tunnel4 esp6 esp4 ah6 ah4 xfrm_algo xt_LOG xt_LED
xt_comment x_tables ipv6
[ 55.134954] CPU: 0 PID: 82 Comm: kworker/0:2 Tainted: G
T 5.8.17 #1
[ 55.142526] Hardware name: Freescale i.MX7 Dual (Device Tree)
[ 55.148304] Workqueue: events acm_softint [cdc_acm]
[ 55.153196] PC is at kobject_get+0x10/0xa4
[ 55.157302] LR is at usb_get_dev+0x14/0x1c
[ 55.161402] pc : [<8047c06c>] lr : [<80560448>] psr: 20000193
[ 55.167671] sp : bca39ea8 ip : 00007374 fp : bf6cbd80
[ 55.172899] r10: 00000000 r9 : bdd92284 r8 : bdd92008
[ 55.178128] r7 : 6b6b6b6b r6 : fffffffe r5 : 60000113 r4 : 6b6b6be3
[ 55.184658] r3 : 6b6b6b6b r2 : 00000111 r1 : 00000000 r0 : 6b6b6be3
[ 55.191191] Flags: nzCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment none
[ 55.198417] Control: 10c5387d Table: bcf0c06a DAC: 00000051
[ 55.204168] Process kworker/0:2 (pid: 82, stack limit = 0x9bdd2a89)
[ 55.210439] Stack: (0xbca39ea8 to 0xbca3a000)
[ 55.214805] 9ea0: bf6cbd80 80769a50 6b6b6b6b 80560448 bdeb0500 8056bfe8
[ 55.222991] 9ec0: 00000002 b76da000 00000000 bdeb0500 bdd92448 bca38000 bdeb0510 8056d69c
[ 55.231177] 9ee0: bca38000 00000000 80c050fc 00000000 bca39f44 09d42015 00000000 00000001
[ 55.239363] 9f00: bdd92448 bdd92438 bdd92000 7f1158c4 bdd92448 bca2ee00 bf6cbd80 bf6cef00
[ 55.247549] 9f20: 00000000 00000000 00000000 801412d8 bf6cbd98 80c03d00 bca2ee00 bf6cbd80
[ 55.255735] 9f40: bca2ee14 bf6cbd98 80c03d00 00000008 bca38000 80141568 00000000 80c446ae
[ 55.263921] 9f60: 00000000 bc9ed880 bc9f0700 bca38000 bc117eb4 80141524 bca2ee00 bc9ed8a4
[ 55.272107] 9f80: 00000000 80147cc8 00000000 bc9f0700 80147b84 00000000 00000000 00000000
[ 55.280292] 9fa0: 00000000 00000000 00000000 80100148 00000000 00000000 00000000 00000000
[ 55.288477] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 55.296662] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
[ 55.304860] [<8047c06c>] (kobject_get) from [<80560448>] (usb_get_dev+0x14/0x1c)
[ 55.312271] [<80560448>] (usb_get_dev) from [<8056bfe8>] (usb_hcd_unlink_urb+0x50/0xd8)
[ 55.320286] [<8056bfe8>] (usb_hcd_unlink_urb) from [<8056d69c>] (usb_kill_urb.part.0+0x44/0xd0)
[ 55.329004] [<8056d69c>] (usb_kill_urb.part.0) from [<7f1158c4>] (acm_softint+0x4c/0x10c [cdc_acm])
[ 55.338082] [<7f1158c4>] (acm_softint [cdc_acm]) from [<801412d8>] (process_one_work+0x19c/0x3e8)
[ 55.346969] [<801412d8>] (process_one_work) from [<80141568>] (worker_thread+0x44/0x4dc)
[ 55.355072] [<80141568>] (worker_thread) from [<80147cc8>] (kthread+0x144/0x180)
[ 55.362481] [<80147cc8>] (kthread) from [<80100148>] (ret_from_fork+0x14/0x2c)
[ 55.369706] Exception stack(0xbca39fb0 to 0xbca39ff8)
Tested-by: Bruno Thomsen <bruno.thomsen@gmail.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210311130126.15972-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 file changed
