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newbus: Create a knob to disable devices that fail to attach.

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Normally, when a device fails to attach, we tear down the newbus state
for that device so that future driver loads can try again (maybe with a
different driver, or maybe with a re-loaded and fixed kld).

Sometimes, however, it is desirable to have the device fail
permanantly. We do this by calling device_disable() on a failed
attached, as well as keeping the device in DS_ATTACHING forever. This
prevents retries on that device. This is enabled via
hw.bus.disable_failed_devices=1 in either a hint via the loader, or at
runtime with a sysctl setting. Setting from 1 -> 0 at runtime will not
affect previously disabled devices, however: they remain disabled.
They can be re-enabled manually with devctl enable, however.

Sponsored by:		Netflix

Reviewed by:	gallatin, hselasky, jhb
Differential Revision:	https://reviews.freebsd.org/D37517
This commit is contained in:
Warner Losh 2022-12-04 16:20:24 -07:00
parent 9f7269677c
commit aa52c6bdd7
1 changed files with 27 additions and 6 deletions
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33
sys/kern/subr_bus.c
View file

@ -69,6 +69,10 @@ SYSCTL_NODE(_hw, OID_AUTO, bus, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
SYSCTL_ROOT_NODE(OID_AUTO, dev, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
NULL);
static bool disable_failed_devs = false;
SYSCTL_BOOL(_hw_bus, OID_AUTO, disable_failed_devices, CTLFLAG_RWTUN, &disable_failed_devs,
0, "Do not retry attaching devices that return an error from DEVICE_ATTACH the first time");
/*
* Used to attach drivers to devclasses.
*/
@ -2533,12 +2537,29 @@ device_attach(device_t dev)
if ((error = DEVICE_ATTACH(dev)) != 0) {
printf("device_attach: %s%d attach returned %d\n",
dev->driver->name, dev->unit, error);
if (!(dev->flags & DF_FIXEDCLASS))
devclass_delete_device(dev->devclass, dev);
(void)device_set_driver(dev, NULL);
device_sysctl_fini(dev);
KASSERT(dev->busy == 0, ("attach failed but busy"));
dev->state = DS_NOTPRESENT;
if (disable_failed_devs) {
/*
* When the user has asked to disable failed devices, we
* directly disable the device, but leave it in the
* attaching state. It will not try to probe/attach the
* device further. This leaves the device numbering
* intact for other similar devices in the system. It
* can be removed from this state with devctl.
*/
device_disable(dev);
} else {
/*
* Otherwise, when attach fails, tear down the state
* around that so we can retry when, for example, new
* drivers are loaded.
*/
if (!(dev->flags & DF_FIXEDCLASS))
devclass_delete_device(dev->devclass, dev);
(void)device_set_driver(dev, NULL);
device_sysctl_fini(dev);
KASSERT(dev->busy == 0, ("attach failed but busy"));
dev->state = DS_NOTPRESENT;
}
return (error);
}
dev->flags |= DF_ATTACHED_ONCE;