Re: [PATCH v2 1/2] sysfs: handle 'parent deleted before child added'
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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. > 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. -- Dan -- 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