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Umesh Nerlige Ramappa 907ef0398c i915/guc: Get runtime pm in busyness worker only if already active
Ideally the busyness worker should take a gt pm wakeref because the
worker only needs to be active while gt is awake. However, the gt_park
path cancels the worker synchronously and this complicates the flow if
the worker is also running at the same time. The cancel waits for the
worker and when the worker releases the wakeref, that would call gt_park
and would lead to a deadlock.

The resolution is to take the global pm wakeref if runtime pm is already
active. If not, we don't need to update the busyness stats as the stats
would already be updated when the gt was parked.

Note:
- We do not requeue the worker if we cannot take a reference to runtime
  pm since intel_guc_busyness_unpark would requeue the worker in the
  resume path.

- If the gt was parked longer than time taken for GT timestamp to roll
  over, we ignore those rollovers since we don't care about tracking the
  exact GT time. We only care about roll overs when the gt is active and
  running workloads.

- There is a window of time between gt_park and runtime suspend, where
  the worker may run. This is acceptable since the worker will not find
  any new data to update busyness.

v2: (Daniele)
- Edit commit message and code comment
- Use runtime pm in the worker
- Put runtime pm after enabling the worker
- Use Link tag and add Fixes tag

v3: (Daniele)
- Reword commit and comments and add details

Link: https://gitlab.freedesktop.org/drm/intel/-/issues/7077
Fixes: 77cdd054dd ("drm/i915/pmu: Connect engine busyness stats from GuC to pmu")
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230925192117.2497058-1-umesh.nerlige.ramappa@intel.com
(cherry picked from commit e2f99b79d4)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
2023-09-26 13:58:16 -04:00
arch ARM: 2023-09-24 14:14:35 -07:00
block blk-mq: fix tags UAF when shrinking q->nr_hw_queues 2023-09-11 16:17:34 -06:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: sm2 - Fix crash caused by uninitialized context 2023-09-20 13:10:10 +08:00
Documentation LoongArch fixes for v6.6-rc3 2023-09-23 10:57:03 -07:00
drivers i915/guc: Get runtime pm in busyness worker only if already active 2023-09-26 13:58:16 -04:00
fs Tracing fixes for 6.6-rc2: 2023-09-24 13:55:34 -07:00
include ARM: 2023-09-24 14:14:35 -07:00
init workqueue: Changes for v6.6 2023-09-01 16:06:32 -07:00
io_uring io_uring/net: fix iter retargeting for selected buf 2023-09-14 10:12:55 -06:00
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kernel Tracing fixes for 6.6-rc2: 2023-09-24 13:55:34 -07:00
lib argv_split: fix kernel-doc warnings 2023-09-19 13:21:33 -07:00
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mm 13 hotfixes, 10 of which pertain to post-6.5 issues. The other 3 are 2023-09-23 11:51:16 -07:00
net Networking fixes for 6.6-rc2, including fixes from netfilter and bpf 2023-09-21 11:28:16 -07:00
rust Documentation work keeps chugging along; stuff for 6.6 includes: 2023-08-30 20:05:42 -07:00
samples VFIO updates for v6.6-rc1 2023-08-30 20:36:01 -07:00
scripts 13 hotfixes, 10 of which pertain to post-6.5 issues. The other 3 are 2023-09-23 11:51:16 -07:00
security selinux: fix handling of empty opts in selinux_fs_context_submount() 2023-09-12 17:31:08 -04:00
sound ASoC: Fixes for v6.6 2023-09-20 15:02:16 +02:00
tools ARM: 2023-09-24 14:14:35 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
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.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
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COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS gpio fixes for v6.6-rc3 2023-09-23 11:56:57 -07:00
Makefile Linux 6.6-rc3 2023-09-24 14:31:13 -07:00
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.