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Oleksij Rempel 3e96cd27ff net: usb: asix: hold PM usage ref to avoid PM/MDIO + RTNL deadlock
commit 3d3c4cd5c62f24bb3cb4511b7a95df707635e00a upstream.

Prevent USB runtime PM (autosuspend) for AX88772* in bind.

usbnet enables runtime PM (autosuspend) by default, so disabling it via
the usb_driver flag is ineffective. On AX88772B, autosuspend shows no
measurable power saving with current driver (no link partner, admin
up/down). The ~0.453 W -> ~0.248 W drop on v6.1 comes from phylib powering
the PHY off on admin-down, not from USB autosuspend.

The real hazard is that with runtime PM enabled, ndo_open() (under RTNL)
may synchronously trigger autoresume (usb_autopm_get_interface()) into
asix_resume() while the USB PM lock is held. Resume paths then invoke
phylink/phylib and MDIO, which also expect RTNL, leading to possible
deadlocks or PM lock vs MDIO wake issues.

To avoid this, keep the device runtime-PM active by taking a usage
reference in ax88772_bind() and dropping it in unbind(). A non-zero PM
usage count blocks runtime suspend regardless of userspace policy
(.../power/control - pm_runtime_allow/forbid), making this approach
robust against sysfs overrides.

Holding a runtime-PM usage ref does not affect system-wide suspend;
system sleep/resume callbacks continue to run as before.

Fixes: 4a2c7217cd ("net: usb: asix: ax88772: manage PHY PM from MAC")
Reported-by: Hubert Wiśniewski <hubert.wisniewski.25632@gmail.com>
Closes: https://lore.kernel.org/all/DCGHG5UJT9G3.2K1GHFZ3H87T0@gmail.com
Tested-by: Hubert Wiśniewski <hubert.wisniewski.25632@gmail.com>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Closes: https://lore.kernel.org/all/b5ea8296-f981-445d-a09a-2f389d7f6fdd@samsung.com
Cc: stable@vger.kernel.org
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://patch.msgid.link/20251005081203.3067982-1-o.rempel@pengutronix.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-10-15 11:56:41 +02:00
arch sparc: fix accurate exception reporting in copy_{from,to}_user for M7 2025-10-15 11:56:36 +02:00
block block: use int to store blk_stack_limits() return value 2025-10-15 11:56:27 +02:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2025-04-25 10:44:04 +02:00
crypto crypto: rng - Ensure set_ent is always present 2025-10-15 11:56:24 +02:00
Documentation Documentation: trace: historgram-design: Separate sched_waking histogram section heading and the following diagram 2025-10-15 11:56:35 +02:00
drivers net: usb: asix: hold PM usage ref to avoid PM/MDIO + RTNL deadlock 2025-10-15 11:56:41 +02:00
fs ext4: fix checks for orphan inodes 2025-10-15 11:56:40 +02:00
include bpf: Enforce expected_attach_type for tailcall compatibility 2025-10-15 11:56:29 +02:00
init init: INITRAMFS_PRESERVE_MTIME should depend on BLK_DEV_INITRD 2025-10-15 11:56:25 +02:00
io_uring io_uring: include dying ring in task_work "should cancel" state 2025-09-25 10:58:53 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:07:30 +01:00
kernel bpf: Enforce expected_attach_type for tailcall compatibility 2025-10-15 11:56:29 +02:00
lib minmax: don't use max() in situations that want a C constant expression 2025-10-15 11:56:21 +02:00
LICENSES
mm mm: hugetlb: avoid soft lockup when mprotect to large memory area 2025-10-15 11:56:40 +02:00
net net: nfc: nci: Add parameter validation for packet data 2025-10-15 11:56:39 +02:00
rust rust: module: place cleanup_module() in .exit.text section 2025-07-06 10:57:54 +02:00
samples ftrace/samples: Fix function size computation 2025-09-19 16:29:56 +02:00
scripts gcc-plugins: Remove TODO_verify_il for GCC >= 16 2025-10-15 11:56:20 +02:00
security apparmor: use the condition in AA_BUG_FMT even with debug disabled 2025-08-28 16:26:01 +02:00
sound ASoC: Intel: bytcr_rt5651: Fix invalid quirk input mapping 2025-10-15 11:56:33 +02:00
tools nvdimm: ndtest: Return -ENOMEM if devm_kcalloc() fails in ndtest_probe() 2025-10-15 11:56:40 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-06-27 11:07:25 +01:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:46:21 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:21:15 +02:00
.mailmap
.rustfmt.toml
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS sign-file,extract-cert: move common SSL helper functions to a header 2025-04-25 10:44:04 +02:00
Makefile Linux 6.1.155 2025-10-02 13:40:43 +02:00
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