Hi leeman I think it is because iscsi_login_portal() has no protection to avoid parallel searching the sysfs for the same session.
Can we use something like sem to serialize the searching from different processes ? Since I don’t see any communication with iscsid in this login operation, I’m not sure if it is a good idea to do the synchronization in iscsid. Thanks. From: [email protected] [mailto:[email protected]] On Behalf Of The Lee-Man Sent: Wednesday, October 04, 2017 12:27 AM To: open-iscsi <[email protected]> Subject: Re: [iscsiadm] iscsiadm creates multiple same sessions when run with --login option in parallel. Thanks for this report. I'll try to reproduce this myself and see what is going on. It is certainly the case that there is insufficient locking in iscsid with respect to multiple threads, IMHO, so I am not surprised. On Wednesday, September 27, 2017 at 11:43:02 PM UTC-7, Tangchen (UVP) wrote: Hi guys, If we run iscsiadm -m node --login command through the same IP address 4 times, only one session will be created. But if we run them in parallel, then 4 same sessions could be created. ( Here, xxx.xxx.xxx.xxx is the IP address to the IPSAN. I'm using the same IP in these 4 commands. ) # iscsiadm -m node -p xxx.xxx.xxx.xxx --login & # iscsiadm -m node -p xxx.xxx.xxx.xxx --login & # iscsiadm -m node -p xxx.xxx.xxx.xxx --login & # iscsiadm -m node -p xxx.xxx.xxx.xxx --login & Logging in to [iface: default, target: iqn. xxx.xxx.xxx.xxx, portal: xxx.xxx.xxx.xxx] (multiple) Logging in to [iface: default, target: iqn. xxx.xxx.xxx.xxx, portal: xxx.xxx.xxx.xxx] (multiple) Logging in to [iface: default, target: iqn. xxx.xxx.xxx.xxx, portal: xxx.xxx.xxx.xxx] (multiple) Logging in to [iface: default, target: iqn. xxx.xxx.xxx.xxx, portal: xxx.xxx.xxx.xxx] (multiple) Login to [iface: default, target: xxx.xxx.xxx.xxx, portal: xxx.xxx.xxx.xxx] successful. Login to [iface: default, target: xxx.xxx.xxx.xxx, portal: xxx.xxx.xxx.xxx] successful. Login to [iface: default, target: xxx.xxx.xxx.xxx, portal: xxx.xxx.xxx.xxx] successful. Login to [iface: default, target: xxx.xxx.xxx.xxx, portal: xxx.xxx.xxx.xxx] successful. # iscsiadm -m session tcp: [1] xxx.xxx.xxx.xxx (non-flash) tcp: [2] xxx.xxx.xxx.xxx (non-flash) tcp: [3] xxx.xxx.xxx.xxx (non-flash) tcp: [4] xxx.xxx.xxx.xxx (non-flash) If we check the net connection in /proc/net/nf_conntrack, they are 4 TCP connections with different src ports. And if we run logout command only once, all the 4 sessions will be destroyed. Unfortunately, service like multipathd cannot tell the difference between them. If we have 4 same sessions, 4 paths will be created connecting to the dm device. But actually they are the same paths. Referring to the code, iscsiadm command does prevent creating same session by checking /sys/class/iscsi_session/ dir. But no multi-thread protection in there. Any idea how to solve this problem ? Thanks. -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To post to this group, send email to [email protected]<mailto:[email protected]>. Visit this group at https://groups.google.com/group/open-iscsi. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "open-iscsi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/open-iscsi. For more options, visit https://groups.google.com/d/optout.
