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The system is running an iSCSI write test with header and data digests enabled. On the command that resulted in the assert, all of the write data was sent as immediate and unsolicited. The unsolicited data consisted of a single DataOut PDU and it was the iscsi_cmnd resource allocated for receiving the unsolicited DataOut that caused the assert, not the iscsi_cmnd resource tracking the iSCSI write command. As the Recv thread is finishing up with the iscsi_cmnd struct for receiving the final unsolicited DataOut, SCST is call the iscsi_pre_exec function to restart the command and this routine will process the DataOut iscsi_cmnd as it is queued onto the rx_digest_list of the iscsi_cmnd for Write. ffff8a984150c600 is the iscsi_cmnd allocated to track the iSCSI Write command ffff8a984150d680 is the iscsi_cmnd allocated for receiving the Data-out PDU In the logs below, recv thread 3677 just completed receiving the unsolicited DataOut. [ 977.563046] [3677]: do_recv:808:nr_segs 0, bytes_left 0, res 196608 [ 977.563048] [31728]: iscsi_make_conn_rd_active:351:conn ffff8a97d0df1600, rd_state 2, rd_data_ready 1 [ 977.563065] [3677]: do_recv:808:nr_segs 0, bytes_left 0, res 4 [ 977.563069] [31728]: iscsi_make_conn_rd_active:351:conn ffff8a97d0df1600, rd_state 2, rd_data_ready 1 [ 977.563076] [3677]: cmnd_rx_end:3475:cmnd ffff8a984150d680, opcode 5 [ 977.563078] [31728]: iscsi_make_conn_rd_active:351:conn ffff8a97d0df1600, rd_state 2, rd_data_ready 1 [ 977.563081] [3677]: cmnd_rx_end:3478:Updated last_rcv_time 4295644274 [ 977.563091] [3677]: data_out_end:2455:cmnd ffff8a984150d680, req ffff8a984150c600 [ 977.563093] [3677]: cmd_add_on_rx_ddigest_list:820:Adding RX ddigest cmd ffff8a984150d680 to digest list of req ffff8a984150c600 [ 977.563096] [3677]: cmnd_get:764:cmnd ffff8a984150d680, new cmnd->ref_cnt 2 Here we see no more data is pending to be received on this write, so iscsi_restart_cmnd is called by recv thread which should trigger SCST to start processing the command: [ 977.563106] [3677]: data_out_end:2495:req ffff8a984150c600, FINAL 80, outstanding_r2t 0, r2t_len_to_receive 0, r2t_len_to_send 0 [ 977.563108] [3677]: req_del_from_write_timeout_list:141:Deleting cmd ffff8a984150c600 from conn ffff8a97d0df1600 write_timeout_list [ 977.563111] [3677]: cmnd_remove_data_wait_hash:1606:Deleting cmnd ffff8a984150c600 from the hash (ITT 1e230400) SCST thread 24654 calls the pre execute routine which verifies the data digest on immediate and unsolicited data: [ 977.563157] [24654]: iscsi_pre_exec:1917:Checking digest of RX ddigest cmd ffff8a984150c600 [ 977.563161] [24654]: digest_data:125:req ffff8a984150c600, idx 0, count 16, sg_cnt 64, size 65536, offset 0 [ 977.563170] [24654]: digest_rx_data:219:RX data digest OK for cmd ffff8a984150c600 [ 977.563173] [3677]: cmnd_put:775:cmnd ffff8a984150c600, new ref_cnt 2 [ 977.563176] [24654]: cmd_del_from_rx_ddigest_list:830:Deleting RX digest cmd ffff8a984150c600 from digest list Recv thread calls pre release on iscsi_cmnd allocated for unsolicited DataOut PDU: [ 977.563178] [3677]: req_cmnd_pre_release:820:req ffff8a984150d680 [ 977.563181] [24654]: cmnd_put:775:cmnd ffff8a984150c600, new ref_cnt 1 SCST thread 24654 processing data digest on unsolicited DataOut PDU. Here we have two threads accessing the same iscsi_cmnd struct. SCST thread will set on_rx_digest_list flag to 0. Recv thread will set release_called flag to 1. [ 977.563184] [24654]: iscsi_pre_exec:1917:Checking digest of RX ddigest cmd ffff8a984150d680 [ 977.563186] [24654]: cmd_del_from_rx_ddigest_list:830:Deleting RX digest cmd ffff8a984150d680 from digest list [ 977.563189] [24654]: cmnd_put:775:cmnd ffff8a984150d680, new ref_cnt 0 [ 977.563191] [3677]: conn_get:868:conn ffff8a97d0df1600, new conn_ref_cnt 4 [ 977.563194] [24654]: cmnd_done:589:cmnd ffff8a984150d680 [ 977.563196] BUG at ./iscsi-scst/kernel/iscsi.c:598 (cmnd->on_rx_digest_list) [ 977.563212] ------------[ cut here ]------------ [ 977.563215] kernel BUG at ./iscsi-scst/kernel/iscsi.c:598! Reported and analyzed by Adam Hutchinson <ajhutchin@gmail.com> git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@7338 d57e44dd-8a1f-0410-8b47-8ef2f437770f
Overview ======== This is the SCST development repository. It contains not a single project SCST as one can think, but a number of them, which are divided as the following: 1. SCST core in scst/ subdirectory 2. Administration utility for SCST core scstadmin in scstadmin/ 3. Target drivers in own subdirectories qla2x00t/, iscsi-scst/, etc. 4. User space programs in usr/ subdirectory, like fileio_tgt. 5. Some various docs in doc/ subdirectory. Those subprojects are in most cases independent from each other, although some of them depend from the SCST core. They put in the single repository only to simplify their development, they are released independently. Thus, use "make all" only if you really need to build everything. Otherwise build only what you need, like for iSCSI-SCST: make scst scst_install iscsi iscsi_install For more information about each subproject see their README files. QLogic target driver ==================== QLogic target driver qla2x00t is the old driver, forked from qla2xxx several years ago. It is very stable, well tested and actively used in many production setups. The ultimate goal is to have the mainstream (git) QLogic target driver to be the main and the only QLogic target driver, but, unfortunately, this driver not yet reached level of quality and maturity of qla2x00t. We with QLogic are working toward it. You can find the latest version of the git driver in git://git.qlogic.com/scst-qla2xxx.git. It is maintained by QLogic, hence located in the QLogic's git. To integrate it into the SCST build tree you need: 1. Clone the QLogic git tree somewhere in your system. 2. Create in the SCST root, i.e. this directory, a subdirectory with name qla2x00t_git 3. Optional for the in-tree build: symlink drivers/scsi/qla2xxx subdirectory in the cloned git tree to the qla2x00t_git subdirectory Thats all. Now common and QLA specific root Makefile targets "magically" start working with the new driver. For detail instructions how to setup QLA target build environment see its README or HOWTO. Run either "make all" to build the SCST core and all target drivers with in-tree QLogic drivers, or the following command with standalone QLogic drivers: BUILD_2X_MODULE=y CONFIG_SCSI_QLA_FC=y CONFIG_SCSI_QLA2XXX_TARGET=y make all In presence of qla2x00t_git subdirectory you can still build the qla2x00t using qla_old* root Makefile targets. Vladislav Bolkhovitin <vst@vlnb.net>, http://scst.sourceforge.net