https://bugzilla.kernel.org/show_bug.cgi?id=216059 --- Comment #1 from Sagar (sagar.biradar@xxxxxxxxxxxxx) --- (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. -- You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.
