On Fri, Apr 06, 2012 at 02:06:50PM -0700, Williams, Dan J wrote: > On Fri, Apr 6, 2012 at 1:45 PM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > On Fri, Apr 06, 2012 at 01:41:06PM -0700, Dan Williams wrote: > >> In scsi at least two cases of the parent device being deleted before the > >> child is added have been observed. > >> > >> 1/ scsi is performing async scans and the device is removed prior to the > >> async can thread running (can happen with an in-opportune / unlikely > >> unplug during initial scan). > > > > That sounds like a bug in the scsi code, doesn't it? > > > >> 2/ libsas discovery event running after the parent port has been torn > >> down (this is a bug in libsas). > > > > Is this fixed somewhere? > > Yes, these two issues have pending fixes that are posted to linux-scsi: > > http://marc.info/?l=linux-scsi&m=133239707903443&w=2 > http://marc.info/?l=linux-scsi&m=133239709603452&w=2 > > > I don't want to paper over bugs like this by changing the sysfs core. > > We went through this a lot years ago when scsi changed to use the driver > > core, and I thought we had fixed all of these types of errors properly. > > Hotplug lifetime rules are still transport specific. So in this case > scsi-core is innocent these are bugs from libsas and > scsi_transport_sas. Ok, thanks for the explaination. > > So, any chance to fix these properly as well? > > This patch doesn't really paper over anything. It turns a NULL > pointer crash into an explicit warning from kobject_add_internal. For > the libsas/scsi case this device_add() failure is still fatal. > Regardless of whether sysfs changes the above two fixes are still > required. > > Since the -EEXIST case is just a KERN_ERR and not a BUG_ON I figured > it was worthwhile to post a patch to do the same for this 'parent > deleted' case. But if crashing is the expectation then this patch can > be dropped. No, crashing is not the expectation :) But, without that crash, would the above fixes ever have been noticed and fixed? The device_add() most likely would have quietly failed and no one would have been the wiser. Or would something else have caused this to be an obvious problem? thanks, greg k-h -- 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
