> > They're not the same. I don't see how your solution properly deals with > remote sas_port deletion. > > When we unplug a device connected to an expander, can't the sas_port be > deleted twice, in sas_unregister_devs_sas_addr() from domain revalidation and > also now in sas_destruct_devices()? I think that this gives a NULL > dereference. > And we still get the WARN as the sas_port has still been deleted before the > device. > > In my solution, we should always delete the sas_port after the attached > device. > >>> >>> i.e. it moves the port destruction to the workqueue and still suffers >>> from the flutter problem: >>> >>> http://marc.info/?l=linux-scsi&m=143801026028006&w=2 >>> http://marc.info/?l=linux-scsi&m=143801971131073&w=2 >>> >>> Perhaps we instead need to quiet this warning? >>> >>> http://marc.info/?l=linux-scsi&m=143802229932175&w=2 > > I have not seen the flutter issue. I am just trying to solve the horrible > WARN dump. > However I do understand that there may be a issue related to how we queue the > events; there was a recent attempt to fix this, but it came to nothing: > https://www.spinics.net/lists/linux-scsi/msg99991.html
We found libsas hotplug several problems: 1. sysfs warning calltrace(like the case you found); 2. hot-add and hot-remove work events may process out of order; 3. in some extreme cases, libsas may miss some events, if the same event is still pending in workqueue. It's a complex issue, we posted two patches, try to fix these issues, but now few people are interested in it :( > > Cheers, > John > >> >> Alternatively we need a mechanism to cancel in-flight port shutdown >> requests when we start re-attaching devices before queued port >> destruction events have run. >> >> . >> > > > _______________________________________________ > linuxarm mailing list > linux...@huawei.com > http://rnd-openeuler.huawei.com/mailman/listinfo/linuxarm > > . >
