Linux kernel source tree
Go to file
Chris Lew 544d85de4d net: qrtr: Send HELLO message on endpoint register
HELLO is currently handled entirely by the name server (NS): it is
sent once as a broadcast when the NS initializes, and again as a
reply whenever the NS receives an inbound HELLO from a remote.

Some remote QRTR endpoints (e.g. an external WLAN chipset attached
over MHI) operate in a slave role: they only ever send a HELLO in
response to one they receive, and never initiate. Since the host cannot
tell in advance which remotes behave this way, if the host also only
replies, both sides wait on the other to speak first and no HELLO is
ever exchanged, stalling further communication.

To fix this:
- Transfer HELLO handshake ownership to the core layer. A HELLO is
  now sent once, per endpoint, at registration time.
- Schedule a delayed work item on endpoint registration to send a
  HELLO once the name server is bound. The work reschedules itself
  with a 100ms backoff if the name server socket is not yet bound or
  if allocating the control packet fails, so a transient startup
  condition does not abandon the handshake permanently.
- Enforce HELLO-first ordering by dropping non-HELLO packets and
  returning -EAGAIN until the HELLO is confirmed sent, using bool
  hello_sent guarded by ep_lock to make the gate check atomic with
  xmit().
- Skip nodes with nid == QRTR_EP_NID_AUTO in bcast_enqueue(), to avoid
  broadcasting control packets with QRTR_EP_NID_AUTO as the destination
  node ID.
- Remove say_hello() from the name server's ctrl_cmd_hello() handler
  and from qrtr_ns_init(); the core layer is now the sole sender of
  the outbound HELLO. This removes the NS's reply-on-receive
  behaviour without a replacement.

Signed-off-by: Chris Lew <christopher.lew@oss.qualcomm.com>
Co-developed-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
Signed-off-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
Co-developed-by: Pranav Mahesh Phansalkar <pranav.phansalkar@oss.qualcomm.com>
Signed-off-by: Pranav Mahesh Phansalkar <pranav.phansalkar@oss.qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2026-09-02 12:14:32 +01:00
arch MFD for v7.3 2026-08-27 10:45:08 -07:00
block for-7.3/block-20260819 2026-08-20 13:55:16 -07:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto This update includes the following changes: 2026-08-19 17:25:42 -07:00
Documentation netlink: specs: add missing mask attributes for conntrack dump 2026-08-28 15:34:51 -07:00
drivers octeontx2-af: Fix limiting SRIOV VF count logic 2026-09-02 09:49:27 +01:00
fs mm.git review status for linus..mm-stable 2026-08-27 09:17:06 -07:00
include ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source() 2026-08-31 17:54:45 -07:00
init Bootconfig updates for v7.3: 2026-08-25 08:59:09 -07:00
io_uring fuse update for 7.3 2026-08-25 07:59:44 -07:00
ipc mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
kernel dma-mapping fix for Linux 7.3 2026-08-27 12:14:19 -07:00
lib mm.git review status for linus..mm-stable 2026-08-27 09:17:06 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm mm.git review status for linus..mm-stable 2026-08-27 09:17:06 -07:00
net net: qrtr: Send HELLO message on endpoint register 2026-09-02 12:14:32 +01:00
rust USB / Thunderbolt changes for 7.3-rc1 2026-08-25 10:44:46 -07:00
samples Modules changes for 7.3-rc1 2026-08-21 12:47:25 -07:00
scripts Char/Misc/IIO/etc driver update for 7.3-rc1 2026-08-25 09:38:50 -07:00
security + Features 2026-08-26 11:04:24 -07:00
sound MFD for v7.3 2026-08-27 10:45:08 -07:00
tools selftests: net: Add exception cache tests 2026-08-31 19:56:31 -07:00
usr usr: Correct a spelling by changing a letter 2026-08-05 14:51:58 +02:00
virt Arm: 2026-08-25 11:48:04 -07:00
.clang-format drm/bridge: rename drm_for_each_bridge_in_chain_scoped() to drm_for_each_bridge_in_chain() 2026-07-14 17:55:51 +02:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add Nathan Chancellor 2026-08-03 21:10:12 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore SPDX patches for 7.2-rc1 2026-06-22 12:06:22 -07:00
.mailmap Char/Misc/IIO/etc driver update for 7.3-rc1 2026-08-25 09:38:50 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS More ACPI support updates for 7.3-rc1 2026-08-26 14:06:08 -07:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Backlight for v7.3 2026-08-27 11:16:39 -07:00
Makefile Bootconfig updates for v7.3: 2026-08-25 08:59:09 -07:00
README README: remove out of place emdashes 2026-07-15 10:51:29 -06:00

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

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer: Getting started with kernel development
* Academic Researcher: Studying kernel internals and architecture
* Security Expert: Hardening and vulnerability analysis
* Backport/Maintenance Engineer: Maintaining stable kernels
* System Administrator: Configuring and troubleshooting
* Maintainer: Leading subsystems and reviewing patches
* Hardware Vendor: Writing drivers for new hardware
* Distribution Maintainer: Packaging kernels for distros
* AI Coding Assistant: LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst