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Filename Latest commit message Latest commit date
Pedro Tammela 6b02df925e net/sched: act_api: rely on rcu in tcf_idr_check_alloc
[ Upstream commit 4b55e86736d5b492cf689125da2600f59c7d2c39 ]

Instead of relying only on the idrinfo->lock mutex for
bind/alloc logic, rely on a combination of rcu + mutex + atomics
to better scale the case where multiple rtnl-less filters are
binding to the same action object.

Action binding happens when an action index is specified explicitly and
an action exists which such index exists. Example:
  tc actions add action drop index 1
  tc filter add ... matchall action drop index 1
  tc filter add ... matchall action drop index 1
  tc filter add ... matchall action drop index 1
  tc filter ls ...
     filter protocol all pref 49150 matchall chain 0 filter protocol all pref 49150 matchall chain 0 handle 0x1
     not_in_hw
           action order 1: gact action drop
            random type none pass val 0
            index 1 ref 4 bind 3

   filter protocol all pref 49151 matchall chain 0 filter protocol all pref 49151 matchall chain 0 handle 0x1
     not_in_hw
           action order 1: gact action drop
            random type none pass val 0
            index 1 ref 4 bind 3

   filter protocol all pref 49152 matchall chain 0 filter protocol all pref 49152 matchall chain 0 handle 0x1
     not_in_hw
           action order 1: gact action drop
            random type none pass val 0
            index 1 ref 4 bind 3

When no index is specified, as before, grab the mutex and allocate
in the idr the next available id. In this version, as opposed to before,
it's simplified to store the -EBUSY pointer instead of the previous
alloc + replace combination.

When an index is specified, rely on rcu to find if there's an object in
such index. If there's none, fallback to the above, serializing on the
mutex and reserving the specified id. If there's one, it can be an -EBUSY
pointer, in which case we just try again until it's an action, or an action.
Given the rcu guarantees, the action found could be dead and therefore
we need to bump the refcount if it's not 0, handling the case it's
in fact 0.

As bind and the action refcount are already atomics, these increments can
happen without the mutex protection while many tcf_idr_check_alloc race
to bind to the same action instance.

In case binding encounters a parallel delete or add, it will return
-EAGAIN in order to try again. Both filter and action apis already
have the retry machinery in-place. In case it's an unlocked filter it
retries under the rtnl lock.

Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Vlad Buslov <vladbu@nvidia.com>
Link: https://lore.kernel.org/r/20231211181807.96028-2-pctammela@mojatatu.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: d864319871b0 ("net/sched: act_api: fix possible infinite loop in tcf_idr_check_alloc()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-07-05 09:08:23 +02:00
arch mips: bmips: BCM6358: make sure CBR is correctly set 2024-07-05 09:08:22 +02:00
block
certs
crypto crypto: ecrdsa - Fix module auto-load on add_key 2024-06-16 13:28:51 +02:00
Documentation ASoC: dt-bindings: rt5645: add cbj sleeve gpio property 2024-06-16 13:28:31 +02:00
drivers PCI/PM: Avoid D3cold for HP Pavilion 17 PC/1972 PCIe Ports 2024-07-05 09:08:21 +02:00
fs udf: udftime: prevent overflow in udf_disk_stamp_to_time() 2024-07-05 09:08:21 +02:00
include hugetlb_encode.h: fix undefined behaviour (34 << 26) 2024-07-05 09:08:20 +02:00
init
ipc
kernel rcutorture: Fix rcu_torture_one_read() pipe_count overflow comment 2024-07-05 09:08:20 +02:00
lib dyndbg: fix old BUG_ON in >control parser 2024-05-17 11:43:55 +02:00
LICENSES
mm x86/mm/pat: fix VM_PAT handling in COW mappings 2024-04-13 12:51:40 +02:00
net net/sched: act_api: rely on rcu in tcf_idr_check_alloc 2024-07-05 09:08:23 +02:00
samples
scripts kconfig: fix comparison to constant symbols, 'm', 'n' 2024-06-16 13:28:47 +02:00
security
sound ASoC: ti: davinci-mcasp: Fix race condition during probe 2024-07-05 09:08:13 +02:00
tools selftests/bpf: Prevent client connect before server bind in test_tc_tunnel.sh 2024-07-05 09:08:20 +02:00
usr
virt KVM: async_pf: Cleanup kvm_setup_async_pf() 2024-05-02 16:18:32 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.278 2024-06-16 13:28:53 +02:00
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.