On 2016-02-15 23:08, Jakub Kicinski wrote:
On Mon, 15 Feb 2016 08:58:53 +0100, Sean Nyekjaer wrote:
Working with RT patches reveals this driver have some spin_lock issues.
spin_lock moved from sc16is7xx_reg_proc to protect to call to
uart_handle_cts_change as it's the only call that isn't already
protected in serial-core.
Sorry but this does not look fine. You are removing all async items
from the driver. This works for you because in RT code can sleep with
spin locks taken but for upstream it's not acceptable. Did you test
this patch with upstream kernel and lockdep enabled?
Hi
I have a 4.1.y with cherry-pick of the commits from tty-testing
regarding sc16is7xx. (exept the new gpio api)
On our custom board we have 3 sc16is750 on a single SPI channel. I'm
using an FTDI chip(connected to a test PC) TX wired to the 3x RX pins on
the sc16is750.
The problem is easy reproducible just by creating data from the PC at
115200 baud, causes the kernel oops almost immediately.
I have not seen any issues with a vanilla 4.1.y, only when i'm applying
the RT patch and loading the system.
Attached the kernel dump with lockdep enabled
/Sean
================================= [92/1901]
[ INFO: inconsistent lock state ]
4.1.15-rt17-00120-g6a753b6-dirty #10 Not tainted
---------------------------------
inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
mdev/309 [HC1[1]:SC0[0]:HE0:SE1] takes:
((&s->kworker)->lock){?.+...}, at: [<80046c50>]
queue_kthread_work+0x18/0x54
{HARDIRQ-ON-W} state was registered at:
[<80500028>] rt_spin_lock+0x74/0x88
[<80046930>] kthread_worker_fn+0x84/0x198
[<80046820>] kthread+0xd8/0xec
[<8000f658>] ret_from_fork+0x14/0x3c
irq event stamp: 1362
hardirqs last enabled at (1361): [<800bc364>] filemap_map_pages+0x2b0/0x424
hardirqs last disabled at (1362): [<800139b4>] __irq_svc+0x34/0x90
softirqs last enabled at (0): [<80026108>] copy_process.part.2+0x370/0x1650
softirqs last disabled at (0): [< (null)>] (null)
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock((&s->kworker)->lock);
<Interrupt>
lock((&s->kworker)->lock);
*** DEADLOCK ***
3 locks held by mdev/309:
#0: (&mm->mmap_sem){++++++}, at: [<8001d420>] do_page_fault+0x80/0x368
#1: (&mm->page_table_lock){+.+...}, at: [<800e19fc>]
handle_mm_fault+0x630/0xcd0
#2: (rcu_read_lock){......}, at: [<800bc0b4>] filemap_map_pages+0x0/0x424
stack backtrace:
CPU: 0 PID: 309 Comm: mdev Not tainted 4.1.15-rt17-00120-g6a753b6-dirty #10
Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[<80016e58>] (unwind_backtrace) from [<80012e48>] (show_stack+0x10/0x14)
[<80012e48>] (show_stack) from [<804fb00c>] (dump_stack+0x7c/0x90)
[<804fb00c>] (dump_stack) from [<804f8c6c>] (print_usage_bug+0x2d8/0x2e8)
[<804f8c6c>] (print_usage_bug) from [<800665ec>] (mark_lock+0x214/0x7a0)
[<800665ec>] (mark_lock) from [<800678dc>] (__lock_acquire+0x778/0x1dd8)
[<800678dc>] (__lock_acquire) from [<800697d4>] (lock_acquire+0x6c/0x8c)
[<800697d4>] (lock_acquire) from [<80500028>] (rt_spin_lock+0x74/0x88)
[<80500028>] (rt_spin_lock) from [<80046c50>] (queue_kthread_work+0x18/0x54)
[<80046c50>] (queue_kthread_work) from [<7f00b260>]
(sc16is7xx_irq+0x10/0x18 [sc16is7xx])
[<7f00b260>] (sc16is7xx_irq [sc16is7xx]) from [<800734c0>]
(handle_irq_event_percpu+0x70/0x15c)
[<800734c0>] (handle_irq_event_percpu) from [<800735e8>]
(handle_irq_event+0x3c/0x5c)
[<800735e8>] (handle_irq_event) from [<80076890>]
(handle_level_irq+0xc4/0x13c)
[<80076890>] (handle_level_irq) from [<80072b2c>]
(generic_handle_irq+0x2c/0x3c)
[<80072b2c>] (generic_handle_irq) from [<8025f8e0>]
(mxc_gpio_irq_handler+0x3c/0x108)
[<8025f8e0>] (mxc_gpio_irq_handler) from [<8025fa2c>]
(mx3_gpio_irq_handler+0x80/0xcc)
[<8025fa2c>] (mx3_gpio_irq_handler) from [<80072b2c>]
(generic_handle_irq+0x2c/0x3c)
[<80072b2c>] (generic_handle_irq) from [<80072e1c>]
(__handle_domain_irq+0x7c/0xe8)
[<80072e1c>] (__handle_domain_irq) from [<800094dc>]
(gic_handle_irq+0x24/0x5c)
[<800094dc>] (gic_handle_irq) from [<800139c4>] (__irq_svc+0x44/0x90)
Exception stack(0xa9ecdda0 to 0xa9ecdde8)
dda0: 00000001 00000110 00000000 a9f40b00 20070113 00000001 aa811eb8
80782edf
ddc0: a9ecde84 aaa231a0 aaa232ec aae4b800 00000003 a9ecdde8 80066be0
800bc368
dde0: 20070113 ffffffff
[<800139c4>] (__irq_svc) from [<800bc368>] (filemap_map_pages+0x2b4/0x424)
[<800bc368>] (filemap_map_pages) from [<800e1b0c>]
(handle_mm_fault+0x740/0xcd0)
[<800e1b0c>] (handle_mm_fault) from [<8001d604>] (do_page_fault+0x264/0x368)
[<8001d604>] (do_page_fault) from [<800093b4>] (do_PrefetchAbort+0x34/0x9c)
[<800093b4>] (do_PrefetchAbort) from [<80013e9c>]
(ret_from_exception+0x0/0x24)
Exception stack(0xa9ecdfb0 to 0xa9ecdff8)
dfa0: 003f8008 00001000 00079c84
7ed0bf99
dfc0: 000808f0 ffffffff 7ed0bfc3 003f8008 00000000 00000000 000808f0
00000001
dfe0: 76e18598 7ed0bc28 00040d1c 76e18598 60070010 ffffffff
random: nonblocking pool is initialized
------------[ cut here ]------------
Kernel BUG at 804fe6d8 [verbose debug info unavailable]
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
Modules linked in: gpio_sn65hvs885 ti_ads8688 ad5755 sc16is7xx
regmap_spi gpio_pca953x
CPU: 0 PID: 215 Comm: kworker/0:2 Not tainted
4.1.15-rt17-00120-g6a753b6-dirty #10
Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree) [17/1901]
Workqueue: events flush_to_ldisc
task: aa414d00 ti: a9c0c000 task.ti: a9c0c000
PC is at rt_spin_lock_slowlock+0x2c8/0x2e4
LR is at rt_spin_lock_slowlock+0x54/0x2e4
pc : [<804fe6d8>] lr : [<804fe464>] psr: 60070193
sp : a9c0dc20 ip : aa414d01 fp : a9edc0c4
r10: 00000000 r9 : 80046be0 r8 : 80782e40
r7 : aa414d00 r6 : 00000000 r5 : 00000001 r4 : a9c0dc38
r3 : aa414d00 r2 : 00000000 r1 : aa414d00 r0 : 00000000
Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment kernel
Control: 10c5387d Table: 39fe804a DAC: 00000015
Process kworker/0:2 (pid: 215, stack limit = 0xa9c0c210)
Stack: (0xa9c0dc20 to 0xa9c0e000)
dc20: a9c0dce0 aac0c000 a9c0dd64 800697d4 00000001 00000080 a9c0dc38
800735f4
dc40: 00000000 a9c0dc44 00000000 aad6b868 00000000 00000002 00000001
804ff9ac
dc60: aa414d00 a9edc0c4 80046c50 00000067 aad96400 80782e40 80046be0
00000000
dc80: c0ac9018 80500038 00000001 00000001 80f8474c 80748984 7f00b250
a9edc0c4
dca0: a9edc11c 80046c50 7f00b250 a9efb2c0 00000000 7f00b260 7f00b250
800734c0
dcc0: 800777d4 00000004 00060002 aad96400 aad96468 a9efb2c0 aad41610
00000001
dce0: 80f8474c 80748984 c0ac9018 800735e8 aad96400 aad96468 00000002
80076890
dd00: 800767cc 00000067 00000004 80072b2c 00000004 8025f8e0 d17b30c0
00000001
dd20: 8073e500 a9fdc200 00000000 aad41610 80751108 aad95a00 00000000
00000001
dd40: a9c0dda0 aac0c000 c0ac9018 8025fa2c 00000063 00000000 00000063
80072b2c
dd60: 8073c6d0 80072e1c f400010c 00000056 80748ca0 a9c0dda0 f4000100
00000008
dd80: a9fe2000 800094dc 80046be0 60070013 ffffffff a9c0ddd4 ffffffff
800139c4
dda0: a9edc0c4 a9edc268 a9edc108 a9edc108 a9edc268 a9edc108 a9edc0c4
a9fe38a9
ddc0: ffffffff 00000008 a9fe2000 c0ac9018 a9c0dda8 a9c0dde8 80046c88
80046be0
dde0: 60070013 ffffffff a9edc0c4 00000001 00000000 80046c88 aa4f8800
a9edc12c
de00: a9fe2000 802a6914 aa414d00 802a75f8 802a7608 c0ac9000 c0ac9000
80292ce8
de20: 60070013 a9fe39a1 a9fe38a1 00000008 c0ac9000 00000000 00000008
80526d20
de40: 55555556 c0ac9000 00000000 a9fe2124 00000000 a9fe2000 aa5722a0
a9ea5cc0
de60: a9fe3800 aa572280 aa57227c 00000000 00000000 80293120 00000001
aa572280
de80: a9fe2000 80296374 00000000 80040ee0 aa678d00 aa572280 ab70ce80
a9c0dec8
dea0: ab710700 00000001 00000000 80040f60 00000001 00000000 80040ee0
800412cc
dec0: 00000000 00000000 80f87484 00000000 00000000 80663790 80782dca
ab70ce80
dee0: ab70ced4 a9c0c000 80782dca aa678d18 aa678d00 00000008 ab70ce80
80041230
df00: 80742a40 aa414d00 aa678d00 aa655c00 00000000 aa678d00 800411e4
00000000
df20: 00000000 00000000 00000000 80046820 a9c0df9c 00000000 aa414d00
aa678d00
df40: 00000000 00000000 dead4ead ffffffff ffffffff 80785368 00000000
00000000
df60: 8066b7cc a9c0df64 a9c0df64 00000000 00000000 dead4ead ffffffff
ffffffff
df80: 80785368 00000000 00000000 8066b7cc a9c0df90 a9c0df90 a9c0dfac
aa655c00
dfa0: 80046748 00000000 00000000 8000f658 00000000 00000000 00000000
00000000
dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00000000
dfe0: 00000000 00000000 00000000 00000000 00000013 00000000 3bf5a811
3bf5ac11
[<804fe6d8>] (rt_spin_lock_slowlock) from [<80500038>]
(rt_spin_lock+0x84/0x88)
[<80500038>] (rt_spin_lock) from [<80046c50>] (queue_kthread_work+0x18/0x54)
[<80046c50>] (queue_kthread_work) from [<7f00b260>]
(sc16is7xx_irq+0x10/0x18 [sc16is7xx])
[<7f00b260>] (sc16is7xx_irq [sc16is7xx]) from [<800734c0>]
(handle_irq_event_percpu+0x70/0x15c)
[<800734c0>] (handle_irq_event_percpu) from [<800735e8>]
(handle_irq_event+0x3c/0x5c)
[<800735e8>] (handle_irq_event) from [<80076890>]
(handle_level_irq+0xc4/0x13c)
[<80076890>] (handle_level_irq) from [<80072b2c>]
(generic_handle_irq+0x2c/0x3c)
[<80072b2c>] (generic_handle_irq) from [<8025f8e0>]
(mxc_gpio_irq_handler+0x3c/0x108)
[<8025f8e0>] (mxc_gpio_irq_handler) from [<8025fa2c>]
(mx3_gpio_irq_handler+0x80/0xcc)
[<8025fa2c>] (mx3_gpio_irq_handler) from [<80072b2c>]
(generic_handle_irq+0x2c/0x3c)
[<80072b2c>] (generic_handle_irq) from [<80072e1c>]
(__handle_domain_irq+0x7c/0xe8)
[<80072e1c>] (__handle_domain_irq) from [<800094dc>]
(gic_handle_irq+0x24/0x5c)
[<800094dc>] (gic_handle_irq) from [<800139c4>] (__irq_svc+0x44/0x90)
Exception stack(0xa9c0dda0 to 0xa9c0dde8)
dda0: a9edc0c4 a9edc268 a9edc108 a9edc108 a9edc268 a9edc108 a9edc0c4
a9fe38a9
ddc0: ffffffff 00000008 a9fe2000 c0ac9018 a9c0dda8 a9c0dde8 80046c88
80046be0
dde0: 60070013 ffffffff
[<800139c4>] (__irq_svc) from [<80046be0>] (insert_kthread_work+0x28/0x80)
[<80046be0>] (insert_kthread_work) from [<80046c88>]
(queue_kthread_work+0x50/0x54)
[<80046c88>] (queue_kthread_work) from [<802a6914>] (__uart_start+0x38/0x3c)
[<802a6914>] (__uart_start) from [<802a75f8>] (uart_start+0x24/0x34)
[<802a75f8>] (uart_start) from [<80292ce8>]
(n_tty_receive_buf_common+0x55c/0x980)
[<80292ce8>] (n_tty_receive_buf_common) from [<80293120>]
(n_tty_receive_buf2+0x14/0x1c)
[<80293120>] (n_tty_receive_buf2) from [<80296374>]
(flush_to_ldisc+0xd4/0x188)
[<80296374>] (flush_to_ldisc) from [<80040f60>]
(process_one_work+0x1a0/0x424)
[<80040f60>] (process_one_work) from [<80041230>] (worker_thread+0x4c/0x4cc)
[<80041230>] (worker_thread) from [<80046820>] (kthread+0xd8/0xec)
[<80046820>] (kthread) from [<8000f658>] (ret_from_fork+0x14/0x3c)
Code: 0a000002 e59d3018 e1530004 0a000000 (e7f001f2)
---[ end trace 0000000000000002 ]---
Kernel panic - not syncing: Fatal exception in interrupt
CPU1: stopping
CPU: 1 PID: 0 Comm: swapper/1 Tainted: G D
4.1.15-rt17-00120-g6a753b6-dirty #10
Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[<80016e58>] (unwind_backtrace) from [<80012e48>] (show_stack+0x10/0x14)
[<80012e48>] (show_stack) from [<804fb00c>] (dump_stack+0x7c/0x90)
[<804fb00c>] (dump_stack) from [<80015d4c>] (handle_IPI+0x17c/0x190)
[<80015d4c>] (handle_IPI) from [<80009510>] (gic_handle_irq+0x58/0x5c)
[<80009510>] (gic_handle_irq) from [<800139c4>] (__irq_svc+0x44/0x90)
Exception stack(0xaacadf58 to 0xaacadfa0)
df40: 8036afbc
aaca2100
df60: 00000001 00000000 ba4c1c99 0000000f d76b24e1 0000000f 00000001
ab7197e8
df80: 8073a894 00000001 aacac000 aacadfa0 8036afbc 8036afc0 60000013
ffffffff
[<800139c4>] (__irq_svc) from [<8036afc0>] (cpuidle_enter_state+0xbc/0x1f4)
[<8036afc0>] (cpuidle_enter_state) from [<80063198>]
(cpu_startup_entry+0x23c/0x394)
[<80063198>] (cpu_startup_entry) from [<100095ac>] (0x100095ac)
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