Re: [PATCH net-next v2 06/10] net: usb: lan78xx: Improve error handling in EEPROM and OTP operations

On Wed, Dec 04, 2024 at 09:41:38AM +0100, Oleksij Rempel wrote:

Refine error handling in EEPROM and OTP read/write functions by:
- Return error values immediately upon detection.
- Avoid overwriting correct error codes with `-EIO`.
- Preserve initial error codes as they were appropriate for specific
  failures.
- Use `-ETIMEDOUT` for timeout conditions instead of `-EIO`.

This patch (which is in Linus' tree) appears to break booting with a NFS
root filesystem on Raspberry Pi 3B+.  There appears to be at least no
incoming traffic seen on the device, I've not checked if there's
anything outgoing:

[   19.234086] usb 1-1.1.1: new high-speed USB device number 6 using dwc2
[   19.394134] brcmfmac: brcmf_sdio_htclk: HT Avail timeout (1000000): clkctl 0x50
[   19.710839] lan78xx 1-1.1.1:1.0 enxb827ebea22ac: renamed from eth0
Device /sys/class/net/enxb827ebea22ac found
done.
Begin: Waiting up to 180 secs for any network device to become available ... done.
IP-Config: enxb827ebea22ac hardware address b8:27:eb:ea:22:ac mt[   20.663606] lan78xx 1-1.1.1:1.0 enxb827ebea22ac: Link is Down
u 1500 DHCP
[   22.708103] lan78xx 1-1.1.1:1.0 enxb827ebea22ac: Link is Up - 1Gbps/Full - flow control off
IP-Config: no response after 2 secs - giving up

The link did look like it was up on the switch.  Full log:

   https://lava.sirena.org.uk/scheduler/job/1158809#L965

A bisect points to this commit fairly cleanly:

git bisect start
# status: waiting for both good and bad commits
# bad: [7eb172143d5508b4da468ed59ee857c6e5e01da6] Linux 6.14-rc5
git bisect bad 7eb172143d5508b4da468ed59ee857c6e5e01da6
# status: waiting for good commit(s), bad commit known
# good: [ffd294d346d185b70e28b1a28abe367bbfe53c04] Linux 6.13
git bisect good ffd294d346d185b70e28b1a28abe367bbfe53c04
# bad: [f1c243fc78ca94fd72e2e6e8f0f49b7360fef475] Merge tag 'iommu-updates-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/iommu/linux
git bisect bad f1c243fc78ca94fd72e2e6e8f0f49b7360fef475
# good: [5f537664e705b0bf8b7e329861f20128534f6a83] cachestat: fix page cache statistics permission checking
git bisect good 5f537664e705b0bf8b7e329861f20128534f6a83
# bad: [7b081a74c07d9e097f6829a1749f0aa441553c5e] Merge tag 'regulator-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator
git bisect bad 7b081a74c07d9e097f6829a1749f0aa441553c5e
# bad: [7b24f164cf005b9649138ef6de94aaac49c9f3d1] Merge tag 'ipsec-next-2025-01-09' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next
git bisect bad 7b24f164cf005b9649138ef6de94aaac49c9f3d1
# bad: [75e2c86c7b180fd1068ad271178c2820a199e7eb] net: netlink: catch attempts to send empty messages
git bisect bad 75e2c86c7b180fd1068ad271178c2820a199e7eb
# bad: [bf361b18d91e96dee50c5794097a80ff3594725c] net: usb: lan78xx: Fix return value handling in lan78xx_set_features
git bisect bad bf361b18d91e96dee50c5794097a80ff3594725c
# bad: [195c3d4631816f02071f0e01d2d2def51cf5067a] octeontx2-pf: map skb data as device writeable
git bisect bad 195c3d4631816f02071f0e01d2d2def51cf5067a
# good: [dcf3827cde8621d2317a7f98e069adbdc2112982] xdp, xsk: constify read-only arguments of some static inline helpers
git bisect good dcf3827cde8621d2317a7f98e069adbdc2112982
# good: [7a2716ac9a5b2a2dd0443b101766d3721f094ee1] Merge branch 'net-phylib-eee-cleanups'
git bisect good 7a2716ac9a5b2a2dd0443b101766d3721f094ee1
# bad: [18eabadd73ae60023ab05e376246bd725fb0c113] vrf: Make pcpu_dstats update functions available to other modules.
git bisect bad 18eabadd73ae60023ab05e376246bd725fb0c113
# bad: [8b1b2ca83b200fa46fdfb81e80ad5fe34537e6d4] net: usb: lan78xx: Improve error handling in EEPROM and OTP operations
git bisect bad 8b1b2ca83b200fa46fdfb81e80ad5fe34537e6d4
# good: [39aa1d620d10cdd276f4728da50f136dbe939643] net: usb: lan78xx: move functions to avoid forward definitions
git bisect good 39aa1d620d10cdd276f4728da50f136dbe939643
# good: [32ee0dc764505278229078e496e7b56a6d65224b] net: usb: lan78xx: Fix error handling in MII read/write functions
git bisect good 32ee0dc764505278229078e496e7b56a6d65224b
# first bad commit: [8b1b2ca83b200fa46fdfb81e80ad5fe34537e6d4] net: usb: lan78xx: Improve error handling in EEPROM and OTP operations