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Sean Wang 8d32e06243 net: ethernet: mediatek: fixed deadlock captured by lockdep
Lockdep found an inconsistent lock state when mtk_get_stats64 is called
in user context while NAPI updates MAC statistics in softirq.

Use spin_trylock_bh/spin_unlock_bh fix following lockdep warning.

[   81.321030] WARNING: inconsistent lock state
[   81.325266] 4.12.0-rc1-00035-gd9dda65 #32 Not tainted
[   81.330273] --------------------------------
[   81.334505] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
[   81.340464] ksoftirqd/0/7 [HC0[0]:SC1[1]:HE1:SE0] takes:
[   81.345731]  (&syncp->seq#2){+.?...}, at: [<c054ba3c>] mtk_handle_status_irq.part.6+0x70/0x84
[   81.354219] {SOFTIRQ-ON-W} state was registered at:
[   81.359062]   lock_acquire+0xfc/0x2b0
[   81.362696]   mtk_stats_update_mac+0x60/0x2c0
[   81.367017]   mtk_get_stats64+0x17c/0x18c
[   81.370995]   dev_get_stats+0x48/0xbc
[   81.374628]   rtnl_fill_stats+0x48/0x128
[   81.378520]   rtnl_fill_ifinfo+0x4ac/0xd1c
[   81.382584]   rtmsg_ifinfo_build_skb+0x7c/0xe0
[   81.386991]   rtmsg_ifinfo.part.5+0x24/0x54
[   81.391139]   rtmsg_ifinfo+0x24/0x28
[   81.394685]   __dev_notify_flags+0xa4/0xac
[   81.398749]   dev_change_flags+0x50/0x58
[   81.402640]   devinet_ioctl+0x768/0x85c
[   81.406444]   inet_ioctl+0x1a4/0x1d0
[   81.409990]   sock_ioctl+0x16c/0x33c
[   81.413538]   do_vfs_ioctl+0xb4/0xa34
[   81.417169]   SyS_ioctl+0x44/0x6c
[   81.420458]   ret_fast_syscall+0x0/0x1c
[   81.424260] irq event stamp: 3354692
[   81.427806] hardirqs last  enabled at (3354692): [<c0678168>] net_rx_action+0xc0/0x504
[   81.435660] hardirqs last disabled at (3354691): [<c0678134>] net_rx_action+0x8c/0x504
[   81.443515] softirqs last  enabled at (3354106): [<c0101944>] __do_softirq+0x4b4/0x614
[   81.451370] softirqs last disabled at (3354109): [<c012f0c4>] run_ksoftirqd+0x44/0x80
[   81.459134]
[   81.459134] other info that might help us debug this:
[   81.465608]  Possible unsafe locking scenario:
[   81.465608]
[   81.471478]        CPU0
[   81.473900]        ----
[   81.476321]   lock(&syncp->seq#2);
[   81.479701]   <Interrupt>
[   81.482294]     lock(&syncp->seq#2);
[   81.485847]
[   81.485847]  *** DEADLOCK ***
[   81.485847]
[   81.491720] 1 lock held by ksoftirqd/0/7:
[   81.495693]  #0:  (&(&mac->hw_stats->stats_lock)->rlock){+.+...}, at: [<c054ba14>] mtk_handle_status_irq.part.6+0x48/0x84
[   81.506579]
[   81.506579] stack backtrace:
[   81.510904] CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 4.12.0-rc1-00035-gd9dda65 #32
[   81.518668] Hardware name: Mediatek Cortex-A7 (Device Tree)
[   81.524208] [<c0113dc4>] (unwind_backtrace) from [<c010e3f0>] (show_stack+0x20/0x24)
[   81.531899] [<c010e3f0>] (show_stack) from [<c03f9c64>] (dump_stack+0xb4/0xe0)
[   81.539072] [<c03f9c64>] (dump_stack) from [<c017e970>] (print_usage_bug+0x234/0x2e0)
[   81.546846] [<c017e970>] (print_usage_bug) from [<c017f058>] (mark_lock+0x63c/0x7bc)
[   81.554532] [<c017f058>] (mark_lock) from [<c017fe90>] (__lock_acquire+0x654/0x1bfc)
[   81.562217] [<c017fe90>] (__lock_acquire) from [<c0181d04>] (lock_acquire+0xfc/0x2b0)
[   81.569990] [<c0181d04>] (lock_acquire) from [<c054b76c>] (mtk_stats_update_mac+0x60/0x2c0)
[   81.578283] [<c054b76c>] (mtk_stats_update_mac) from [<c054ba3c>] (mtk_handle_status_irq.part.6+0x70/0x84)
[   81.587865] [<c054ba3c>] (mtk_handle_status_irq.part.6) from [<c054c2b8>] (mtk_napi_tx+0x358/0x37c)
[   81.596845] [<c054c2b8>] (mtk_napi_tx) from [<c06782ec>] (net_rx_action+0x244/0x504)
[   81.604533] [<c06782ec>] (net_rx_action) from [<c01015c4>] (__do_softirq+0x134/0x614)
[   81.612306] [<c01015c4>] (__do_softirq) from [<c012f0c4>] (run_ksoftirqd+0x44/0x80)
[   81.619907] [<c012f0c4>] (run_ksoftirqd) from [<c0154680>] (smpboot_thread_fn+0x14c/0x25c)
[   81.628110] [<c0154680>] (smpboot_thread_fn) from [<c014f8cc>] (kthread+0x150/0x180)
[   81.635798] [<c014f8cc>] (kthread) from [<c0109290>] (ret_from_fork+0x14/0x24)

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-07-04 01:43:38 -07:00
arch arm: sunxi: Revert changes merged through net-next. 2017-07-01 14:18:13 -07:00
block block: provide bio_uninit() free freeing integrity/task associations 2017-06-28 15:30:13 -06:00
certs scripts/spelling.txt: add "intialise(d)" pattern and fix typo instances 2017-05-08 17:15:13 -07:00
crypto net: convert sock.sk_refcnt from atomic_t to refcount_t 2017-07-01 07:39:08 -07:00
Documentation Documentation: fix wrong example command 2017-07-03 02:08:34 -07:00
drivers net: ethernet: mediatek: fixed deadlock captured by lockdep 2017-07-04 01:43:38 -07:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-06-30 12:43:08 -04:00
include net, ipv4: convert fib_info.fib_clntref from atomic_t to refcount_t 2017-07-04 01:29:04 -07:00
init Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-10 10:30:46 -07:00
ipc mm: introduce kv[mz]alloc helpers 2017-05-08 17:15:12 -07:00
kernel bpf, verifier: add additional patterns to evaluate_reg_imm_alu 2017-07-03 02:22:52 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-06-30 12:43:08 -04:00
mm slub: make sysfs file removal asynchronous 2017-06-23 16:15:55 -07:00
net net, ipv4: convert fib_info.fib_clntref from atomic_t to refcount_t 2017-07-04 01:29:04 -07:00
samples bpf: Sample bpf program to set sndcwnd clamp 2017-07-01 16:15:14 -07:00
scripts Kbuild fixes for v4.12 (2nd) 2017-06-24 16:18:00 -07:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-06-21 17:35:22 -04:00
sound ALSA: hda - Apply quirks to Broxton-T, too 2017-06-20 07:52:49 +02:00
tools bpf: add various test cases for verifier selftest 2017-07-03 02:22:52 -07:00
usr initramfs: fix disabling of initramfs (and its compression) 2017-06-02 15:07:37 -07:00
virt KVM: arm/arm64: Handle possible NULL stage2 pud when ageing pages 2017-06-06 15:28:40 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig
MAINTAINERS NFC 4.13 pull request 2017-07-01 14:30:39 -07:00
Makefile Linux 4.12-rc7 2017-06-25 18:30:05 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.