[Bug 216059] Scsi host number of Adaptec RAID controller changes upon a PCIe hotplug and re-insert

[Bug 216059] Scsi host number of Adaptec RAID controller changes upon a PCIe hotplug and re-insert

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=216059

Bjorn Helgaas (bjorn@helgaas.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bjorn@helgaas.com
          Component|PCI                         |Other
           Assignee|drivers_pci@kernel-bugs.osd |scsi_drivers-other@kernel-b
                   |l.org                       |ugs.osdl.org
            Product|Drivers                     |SCSI Drivers

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[Bug 216059] Scsi host number of Adaptec RAID controller changes upon a PCIe hotplug and re-insert

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=216059

--- Comment #1 from Sagar (sagar.biradar@microchip.com) ---
(In reply to Sagar from comment #0)
> Created attachment 301088 [details]
> The attachments contain the log files which capture before and after cases
> for a hotplug host number change
> 
> Summary:
> This issue talks of the smartpqi driver for Adaptec controller, PCIe hotplug
> and the corresponding SCSI host number 
> 
> 
> The Linux message log shows the host number (e.g. [14:2:0:0] storage -
> /dev/sg27) unexpectedly changing when PCIe hot remove is rapidly followed by
> PCIe hot add. The problem appears when the two PCIe events occur in quick
> succession (i.e. less than 2 minutes). Because of the timing factor, the
> issue can appear to be intermittent. The problem has been root caused as a
> kernel issue.
> 
>  
> 
> Investigation:
> Kernel (4.18.11-hotplug-patch) debug prints were added in  the
> “scsi_add_host( )” and “scsi_remove_host ( )” routines. Per the debug prints
> in the log, the scsi host number is released after the PCIe hot add event,
> which forces the kernel use a different host number.
> 
> (debug prints)
> Line 48: [ 1811.461055] smartpqi 0000:b3:00.0: Debuggg . . .
> pqi_unregister_scsi function, before scsi_remove_host, shost->host_num=14  
> //smartpqi requests host num 14 to be removed
> Line 83: [ 2012.125750]  (null): Debuggg . . shost->host_no before
> dev_set_name = host15
> Line 84: [ 2012.126709] smartpqi 0000:b3:00.0: Debuggg . . . before
> scsi_add_host, shost->host_num=15 //upon hot add, kernel allocates host
> number 15, it should be 14
> Line 132: [ 2014.181784] scsi host14: Debuggg . . in scsi_host_dev_release
> function shost_host_no to be removed = 14 //kernel finally frees host number
> 14, but it’s too late
> 
>  
> 
> Conclusion:
> The kernel is not releasing the host number immediately when the smartpqi
> driver calls the scsi_remove_host() routine. If the PCIe cable is added back
> within 2 minutes, the kernel can unexpectedly return a different host
> number. This can lead to applications accessing the wrong device.
> This is a Linux kernel issue and we will be raising a bugzilla on the linux
> kernel.
> 
>  
> 
> Consequence:
> Application accesses wrong device. Rebooting system may still result in
> wrong host number.

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[Bug 216059] Scsi host number of Adaptec RAID controller changes upon a PCIe hotplug and re-insert

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=216059

Sagar (sagar.biradar@microchip.com) changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |INVALID

--- Comment #2 from Sagar (sagar.biradar@microchip.com) ---
This issue can be ignored. I have filed another BZ instead. . .

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