From: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxxxxxxxx> Date: Mon, 28 Jul 2014 11:28:28 -0700 > Tetsuo bisected and found that commit 786235ee "kthread: make > kthread_create() killable" modified kthread_create() to bail as > soon as SIGKILL is received. This is causing some issues with > some drivers and at times boot. Joseph then found that failures > occur as the systemd-udevd process sends SIGKILL to modprobe if > probe on a driver takes over 30 seconds. When this happens probe > will fail on any driver, its why booting on some system will fail > if the driver happens to be a storage related driver. Some folks > have suggested fixing this by modifying kthread_create() to not > leave upon SIGKILL [3], upon review Oleg rejected this change and > the discussion was punted out to systemd to see if the default > timeout could be increased from 30 seconds to 120. The opinion of > the systemd maintainers is that the driver's behavior should > be fixed [4]. Linus seems to agree [5], however more recently even > networking drivers have been reported to fail on probe since just > writing the firmware to a device and kicking it can take easy over > 60 seconds [6]. Benjamim was able to trace the issues recently > reported on cxgb4 down to the same systemd-udevd 30 second timeout [6]. > > This is an alternative solution which enables drivers that are > known to take long to use deferred probe workqueue. This avoids > the 30 second timeout and lets us annotate drivers with long > init sequences. > > As drivers determine a component is not yet available and needs > to defer probe you'll be notified this happen upon init for each > device but now with a message such as: > > pci 0000:03:00.0: Driver cxgb4 requests probe deferral on init > > You should see one of these per struct device probed. It seems we're still discussing this. I think I understand all of the underlying issues, and what I'll say is that perhaps we should use what Greg KH requested but via a helper that is easy to grep for. I don't care if it's something like "module_long_probe_init()" and "module_long_probe_exit()", but it just needs to be some properly named interface which does the whole kthread or whatever bit. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
