linux/include
Vlad Buslov b3650bf76a net: sched: fix err handler in tcf_action_init()
With recent changes that separated action module load from action
initialization tcf_action_init() function error handling code was modified
to manually release the loaded modules if loading/initialization of any
further action in same batch failed. For the case when all modules
successfully loaded and some of the actions were initialized before one of
them failed in init handler. In this case for all previous actions the
module will be released twice by the error handler: First time by the loop
that manually calls module_put() for all ops, and second time by the action
destroy code that puts the module after destroying the action.

Reproduction:

$ sudo tc actions add action simple sdata \"2\" index 2
$ sudo tc actions add action simple sdata \"1\" index 1 \
                      action simple sdata \"2\" index 2
RTNETLINK answers: File exists
We have an error talking to the kernel
$ sudo tc actions ls action simple
total acts 1

        action order 0: Simple <"2">
         index 2 ref 1 bind 0
$ sudo tc actions flush action simple
$ sudo tc actions ls action simple
$ sudo tc actions add action simple sdata \"2\" index 2
Error: Failed to load TC action module.
We have an error talking to the kernel
$ lsmod | grep simple
act_simple             20480  -1

Fix the issue by modifying module reference counting handling in action
initialization code:

- Get module reference in tcf_idr_create() and put it in tcf_idr_release()
instead of taking over the reference held by the caller.

- Modify users of tcf_action_init_1() to always release the module
reference which they obtain before calling init function instead of
assuming that created action takes over the reference.

- Finally, modify tcf_action_init_1() to not release the module reference
when overwriting existing action as this is no longer necessary since both
upper and lower layers obtain and manage their own module references
independently.

Fixes: d349f99768 ("net_sched: fix RTNL deadlock again caused by request_module()")
Suggested-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-04-08 13:47:33 -07:00
..
acpi IOMMU Updates for Linux v5.12 2021-02-22 10:31:29 -08:00
asm-generic RISC-V Patches for the 5.12 Merge Window 2021-02-26 10:28:35 -08:00
clocksource
crypto Keyrings miscellany 2021-02-23 16:09:23 -08:00
drm drm/ttm: make ttm_bo_unpin more defensive 2021-03-15 16:02:30 +01:00
dt-bindings RISC-V Patches for the 5.12 Merge Window 2021-02-26 10:28:35 -08:00
keys
kunit
kvm KVM: arm64: Turn kvm_arm_support_pmu_v3() into a static key 2021-03-06 04:18:40 -05:00
linux ethtool: Remove link_mode param and derive link params from driver 2021-04-07 14:53:04 -07:00
math-emu
media media: rc: compile rc-cec.c into rc-core 2021-03-11 11:40:28 +01:00
memory
misc
net net: sched: fix err handler in tcf_action_init() 2021-04-08 13:47:33 -07:00
pcmcia
ras
rdma RDMA/ipoib: Remove racy Subnet Manager sendonly join checks 2021-02-16 14:42:58 -04:00
scsi
soc RISC-V Patches for the 5.12 Merge Window 2021-02-26 10:28:35 -08:00
sound ALSA/ASoC/SOF/SoundWire: fix Kconfig issues 2021-03-02 18:30:07 +01:00
target scsi: target: core: Add cmd length set before cmd complete 2021-02-22 22:21:29 -05:00
trace workqueue/tracing: Copy workqueue name to buffer in trace event 2021-03-18 12:57:37 -04:00
uapi ethtool: fix kdoc in headers 2021-04-07 14:22:49 -07:00
vdso
video
xen Xen/gnttab: introduce common INVALID_GRANT_{HANDLE,REF} 2021-03-10 16:39:29 -06:00