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Filename Latest commit message Latest commit date
Taehee Yoo 9fa51bbdf7 hsr: avoid debugfs warning message when module is remove
[ Upstream commit 84bb59d773853bc2dda2ac1ef8474c40eb33a3c6 ]

When hsr module is being removed, debugfs_remove() is called to remove
both debugfs directory and file.

When module is being removed, module state is changed to
MODULE_STATE_GOING then exit() is called.
At this moment, module couldn't be held so try_module_get()
will be failed.

debugfs's open() callback tries to hold the module if .owner is existing.
If it fails, warning message is printed.

CPU0				CPU1
delete_module()
    try_stop_module()
    hsr_exit()			open() <-- WARNING
        debugfs_remove()

In order to avoid the warning message, this patch makes hsr module does
not set .owner. Unsetting .owner is safe because these are protected by
inode_lock().

Test commands:
    #SHELL1
    ip link add dummy0 type dummy
    ip link add dummy1 type dummy
    while :
    do
        ip link add hsr0 type hsr slave1 dummy0 slave2 dummy1
	modprobe -rv hsr
    done

    #SHELL2
    while :
    do
        cat /sys/kernel/debug/hsr0/node_table
    done

Splat looks like:
[  101.223783][ T1271] ------------[ cut here ]------------
[  101.230309][ T1271] debugfs file owner did not clean up at exit: node_table
[  101.230380][ T1271] WARNING: CPU: 3 PID: 1271 at fs/debugfs/file.c:309 full_proxy_open+0x10f/0x650
[  101.233153][ T1271] Modules linked in: hsr(-) dummy veth openvswitch nsh nf_conncount nf_nat nf_conntrack nf_d]
[  101.237112][ T1271] CPU: 3 PID: 1271 Comm: cat Tainted: G        W         5.5.0-rc1+ #204
[  101.238270][ T1271] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[  101.240379][ T1271] RIP: 0010:full_proxy_open+0x10f/0x650
[  101.241166][ T1271] Code: 48 c1 ea 03 80 3c 02 00 0f 85 c1 04 00 00 49 8b 3c 24 e8 04 86 7e ff 84 c0 75 2d 4c 8
[  101.251985][ T1271] RSP: 0018:ffff8880ca22fa38 EFLAGS: 00010286
[  101.273355][ T1271] RAX: dffffc0000000008 RBX: ffff8880cc6e6200 RCX: 0000000000000000
[  101.274466][ T1271] RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffff8880c4dd5c14
[  101.275581][ T1271] RBP: 0000000000000000 R08: fffffbfff2922f5d R09: 0000000000000000
[  101.276733][ T1271] R10: 0000000000000001 R11: 0000000000000000 R12: ffffffffc0551bc0
[  101.277853][ T1271] R13: ffff8880c4059a48 R14: ffff8880be50a5e0 R15: ffffffff941adaa0
[  101.278956][ T1271] FS:  00007f8871cda540(0000) GS:ffff8880da800000(0000) knlGS:0000000000000000
[  101.280216][ T1271] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  101.282832][ T1271] CR2: 00007f88717cfd10 CR3: 00000000b9440005 CR4: 00000000000606e0
[  101.283974][ T1271] Call Trace:
[  101.285328][ T1271]  do_dentry_open+0x63c/0xf50
[  101.286077][ T1271]  ? open_proxy_open+0x270/0x270
[  101.288271][ T1271]  ? __x64_sys_fchdir+0x180/0x180
[  101.288987][ T1271]  ? inode_permission+0x65/0x390
[  101.289682][ T1271]  path_openat+0x701/0x2810
[  101.290294][ T1271]  ? path_lookupat+0x880/0x880
[  101.290957][ T1271]  ? check_chain_key+0x236/0x5d0
[  101.291676][ T1271]  ? __lock_acquire+0xdfe/0x3de0
[  101.292358][ T1271]  ? sched_clock+0x5/0x10
[  101.292962][ T1271]  ? sched_clock_cpu+0x18/0x170
[  101.293644][ T1271]  ? find_held_lock+0x39/0x1d0
[  101.305616][ T1271]  do_filp_open+0x17a/0x270
[  101.306061][ T1271]  ? may_open_dev+0xc0/0xc0
[ ... ]

Fixes: fc4ecaeebd ("net: hsr: add debugfs support for display node list")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-01-09 10:20:07 +01:00
arch perf/x86/intel/bts: Fix the use of page_private() 2020-01-09 10:20:07 +01:00
block compat_ioctl: block: handle BLKGETZONESZ/BLKGETNRZONES 2020-01-09 10:19:58 +01:00
certs
crypto KEYS: asymmetric: return ENOMEM if akcipher_request_alloc() fails 2019-12-31 16:46:07 +01:00
Documentation dt-bindings: clock: renesas: rcar-usb2-clock-sel: Fix typo in example 2020-01-09 10:20:05 +01:00
drivers efi: Don't attempt to map RCI2 config table if it doesn't exist 2020-01-09 10:20:07 +01:00
fs Btrfs: only associate the locked page with one async_chunk struct 2020-01-09 10:20:06 +01:00
include net: annotate lockless accesses to sk->sk_pacing_shift 2020-01-09 10:20:07 +01:00
init Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
ipc ipc/sem.c: convert to use built-in RCU list checking 2019-09-25 17:51:41 -07:00
kernel kernel/module.c: wakeup processes in module_wq on module unload 2020-01-09 10:20:02 +01:00
lib lib/ubsan: don't serialize UBSAN report 2020-01-09 10:20:07 +01:00
LICENSES
mm mm/sparse.c: mark populate_section_memmap as __meminit 2020-01-09 10:20:06 +01:00
net hsr: avoid debugfs warning message when module is remove 2020-01-09 10:20:07 +01:00
samples samples/trace_printk: Wait for IRQ work to finish 2020-01-09 10:20:00 +01:00
scripts gcc-plugins: make it possible to disable CONFIG_GCC_PLUGINS again 2020-01-09 10:19:57 +01:00
security apparmor: fix aa_xattrs_match() may sleep while holding a RCU lock 2020-01-09 10:20:00 +01:00
sound ALSA: firewire-motu: Correct a typo in the clock proc string 2020-01-09 10:20:01 +01:00
tools perf callchain: Fix segfault in thread__resolve_callchain_sample() 2020-01-09 10:20:02 +01:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-09 10:20:00 +01:00
virt KVM: arm/arm64: Properly handle faulting of device mappings 2019-12-31 16:46:24 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-22 14:28:14 -08:00
Makefile Linux 5.4.8 2020-01-04 19:19:19 +01:00
README

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.