linux-kernel - Re: [PATCH] kobject: fix suppressing modalias in uevents delivered over netlink

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Date:   Thu, 21 Dec 2017 20:26:40 +0000
From:   Casey Leedom <leedom@...lsio.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        "David S . Miller" <davem@...emloft.net>,
        "Komali Katari" <komali@...lsio.com>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kobject: fix suppressing modalias in uevents delivered
 over netlink

| From: Dmitry Torokhov <dmitry.torokhov@...il.com>
| Sent: Wednesday, December 20, 2017 9:13 PM
|
| The 2nd issue is that Casey is seeing cxgb4vf driver being loaded.
| This happens because vfio-pci driver binds to the device, which causes
| KOBJ_BIND to get emitted, which causes all modules that match the PCI
| device ID that was bound to load [again].
|
| While we could fix the issue by putting another bandaid and zapping
| the modalias on KOBJ_BIND as well, I am not sure we need to do that,
| as I do not see a harm in having cxgb4vf module loaded. Rather than
| patching the kernel I'd recommend Casey simply update the udev scripts
| to only load module on KOBJ_ADD event:
|
| https://github.com/systemd/systemd/commit/9b32afa9f241fe8febc0a754850f1e7331caf6e3#diff-0e123aabb4420b8b95088699179f3416
|
|  https://avatars3.githubusercontent.com/u/1047950?s=200&v=4
|
| rules: load drivers only on "add"        systemd/systemd@...2afa
| github.com
|
| Previously we were loading kernel modules on all device events save for
| "remove". With the introduction of KOBJ_BIND/KOBJ_UNBIND this causes issues,
| as driver modules that have devices bound to the...

Thanks Dmitry.

Now I understand why your kernel.org:1455cf8 changed this behavior.  It
added new BIND/UNBIND events and the current udev rules treated that as a
load event.

I'm not familiar with the format of /etc/udev/rules.d/ files.  Komali's
system doesn't have a 80-drivers.rules entry.  It looks like she can just
add the file with the diff to test this out.  (Although I'm not sure what
"tifm_sd" is ... it looks like a specific driver ...)

Casey