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Sven Van Asbroeck e35df62e04 lan743x: fix issue causing intermittent kernel log warnings
When running this chip on arm imx6, we intermittently observe
the following kernel warning in the log, especially when the
system is under high load:

[   50.119484] ------------[ cut here ]------------
[   50.124377] WARNING: CPU: 0 PID: 303 at kernel/softirq.c:169 __local_bh_enable_ip+0x100/0x184
[   50.132925] IRQs not enabled as expected
[   50.159250] CPU: 0 PID: 303 Comm: rngd Not tainted 5.7.8 #1
[   50.164837] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[   50.171395] [<c0111a38>] (unwind_backtrace) from [<c010be28>] (show_stack+0x10/0x14)
[   50.179162] [<c010be28>] (show_stack) from [<c05b9dec>] (dump_stack+0xac/0xd8)
[   50.186408] [<c05b9dec>] (dump_stack) from [<c0122e40>] (__warn+0xd0/0x10c)
[   50.193391] [<c0122e40>] (__warn) from [<c0123238>] (warn_slowpath_fmt+0x98/0xc4)
[   50.200892] [<c0123238>] (warn_slowpath_fmt) from [<c012b010>] (__local_bh_enable_ip+0x100/0x184)
[   50.209860] [<c012b010>] (__local_bh_enable_ip) from [<bf09ecbc>] (destroy_conntrack+0x48/0xd8 [nf_conntrack])
[   50.220038] [<bf09ecbc>] (destroy_conntrack [nf_conntrack]) from [<c0ac9b58>] (nf_conntrack_destroy+0x94/0x168)
[   50.230160] [<c0ac9b58>] (nf_conntrack_destroy) from [<c0a4aaa0>] (skb_release_head_state+0xa0/0xd0)
[   50.239314] [<c0a4aaa0>] (skb_release_head_state) from [<c0a4aadc>] (skb_release_all+0xc/0x24)
[   50.247946] [<c0a4aadc>] (skb_release_all) from [<c0a4b4cc>] (consume_skb+0x74/0x17c)
[   50.255796] [<c0a4b4cc>] (consume_skb) from [<c081a2dc>] (lan743x_tx_release_desc+0x120/0x124)
[   50.264428] [<c081a2dc>] (lan743x_tx_release_desc) from [<c081a98c>] (lan743x_tx_napi_poll+0x5c/0x18c)
[   50.273755] [<c081a98c>] (lan743x_tx_napi_poll) from [<c0a6b050>] (net_rx_action+0x118/0x4a4)
[   50.282306] [<c0a6b050>] (net_rx_action) from [<c0101364>] (__do_softirq+0x13c/0x53c)
[   50.290157] [<c0101364>] (__do_softirq) from [<c012b29c>] (irq_exit+0x150/0x17c)
[   50.297575] [<c012b29c>] (irq_exit) from [<c0196a08>] (__handle_domain_irq+0x60/0xb0)
[   50.305423] [<c0196a08>] (__handle_domain_irq) from [<c05d44fc>] (gic_handle_irq+0x4c/0x90)
[   50.313790] [<c05d44fc>] (gic_handle_irq) from [<c0100ed4>] (__irq_usr+0x54/0x80)
[   50.321287] Exception stack(0xecd99fb0 to 0xecd99ff8)
[   50.326355] 9fa0:                                     1cf1aa74 00000001 00000001 00000000
[   50.334547] 9fc0: 00000001 00000000 00000000 00000000 00000000 00000000 00004097 b6d17d14
[   50.342738] 9fe0: 00000001 b6d17c60 00000000 b6e71f94 800b0010 ffffffff
[   50.349364] irq event stamp: 2525027
[   50.352955] hardirqs last  enabled at (2525026): [<c0a6afec>] net_rx_action+0xb4/0x4a4
[   50.360892] hardirqs last disabled at (2525027): [<c0d6d2fc>] _raw_spin_lock_irqsave+0x1c/0x50
[   50.369517] softirqs last  enabled at (2524660): [<c01015b4>] __do_softirq+0x38c/0x53c
[   50.377446] softirqs last disabled at (2524693): [<c012b29c>] irq_exit+0x150/0x17c
[   50.385027] ---[ end trace c0b571db4bc8087d ]---

The driver is calling dev_kfree_skb() from code inside a spinlock,
where h/w interrupts are disabled. This is forbidden, as documented
in include/linux/netdevice.h. The correct function to use
dev_kfree_skb_irq(), or dev_kfree_skb_any().

Fix by using the correct dev_kfree_skb_xxx() functions:

in lan743x_tx_release_desc():
  called by lan743x_tx_release_completed_descriptors()
    called by in lan743x_tx_napi_poll()
    which holds a spinlock
  called by lan743x_tx_release_all_descriptors()
    called by lan743x_tx_close()
    which can-sleep
conclusion: use dev_kfree_skb_any()

in lan743x_tx_xmit_frame():
  which holds a spinlock
conclusion: use dev_kfree_skb_irq()

in lan743x_tx_close():
  which can-sleep
conclusion: use dev_kfree_skb()

in lan743x_rx_release_ring_element():
  called by lan743x_rx_close()
    which can-sleep
  called by lan743x_rx_open()
    which can-sleep
conclusion: use dev_kfree_skb()

Fixes: 23f0703c12 ("lan743x: Add main source files for new lan743x driver")
Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com>
Link: https://lore.kernel.org/r/20201112185949.11315-1-TheSven73@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2020-11-14 13:32:22 -08:00
arch Networking fixes for 5.10-rc4, including fixes from the bpf subtree. 2020-11-12 14:02:04 -08:00
block blk-mq: mark flush request as IDLE in flush_end_io() 2020-10-30 08:33:49 -06:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto drivers-5.10-2020-10-12 2020-10-13 13:04:41 -07:00
Documentation Networking fixes for 5.10-rc4, including fixes from the bpf subtree. 2020-11-12 14:02:04 -08:00
drivers lan743x: fix issue causing intermittent kernel log warnings 2020-11-14 13:32:22 -08:00
fs NFS Client Bugfixes for Linux 5.10-rc4 2020-11-12 13:49:12 -08:00
include ip_tunnels: Set tunnel option flag when tunnel metadata is present 2020-11-13 16:58:10 -08:00
init linux-kselftest-kunit-5.10-rc1 2020-10-18 14:45:59 -07:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel Networking fixes for 5.10-rc4, including fixes from the bpf subtree. 2020-11-12 14:02:04 -08:00
lib drm fixes for 5.10-rc3 2020-11-06 12:54:00 -08:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/truncate.c: make __invalidate_mapping_pages() static 2020-11-02 12:14:19 -08:00
net netlabel: fix an uninitialized warning in netlbl_unlabel_staticlist() 2020-11-14 12:07:57 -08:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2020-11-06 17:49:34 -08:00
scripts Networking fixes for 5.10-rc4, including fixes from the bpf subtree. 2020-11-12 14:02:04 -08:00
security ima: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
sound ASoC: Fixes for v5.10 2020-11-05 18:19:32 +01:00
tools Networking fixes for 5.10-rc4, including fixes from the bpf subtree. 2020-11-12 14:02:04 -08:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt kvm: x86/mmu: Support dirty logging for the TDP MMU 2020-10-23 03:42:13 -04:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap MAINTAINERS: jarkko.sakkinen@linux.intel.com -> jarkko@kernel.org 2020-10-16 11:11:19 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Sangbeom Kim to credits 2020-10-26 10:11:18 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 5.10-rc4, including fixes from the bpf subtree. 2020-11-12 14:02:04 -08:00
Makefile Linux 5.10-rc3 2020-11-08 16:10:16 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.