mirror of
https://github.com/SCST-project/scst.git
synced 2026-08-17 04:36:22 +00:00
Tony BattersbyandGleb Chesnokov
41692d22dd
When qla2xxx is loaded with qlini_mode=disabled,
ha->flags.disable_msix_handshake is used before it is set, resulting in
the wrong interrupt handler being used on certain HBAs
(qla2xxx_msix_rsp_q_hs() is used when qla2xxx_msix_rsp_q() should be
used). The only difference between these two interrupt handlers is that
the _hs() version writes to a register to clear the "RISC" interrupt,
whereas the other version does not. So this bug results in the RISC
interrupt being cleared when it should not be. This occasionally causes
a different interrupt handler qla24xx_msix_default() for a different
vector to see ((stat & HSRX_RISC_INT) == 0) and ignore its interrupt,
which then causes problems like:
qla2xxx [0000:02:00.0]-d04c:6: MBX Command timeout for cmd 20,
iocontrol=8 jiffies=1090c0300 mb[0-3]=[0x4000 0x0 0x40 0xda] mb7 0x500
host_status 0x40000010 hccr 0x3f00
qla2xxx [0000:02:00.0]-101e:6: Mailbox cmd timeout occurred, cmd=0x20,
mb[0]=0x20. Scheduling ISP abort
(the cmd varies; sometimes it is 0x20, 0x22, 0x54, 0x5a, 0x5d, or 0x6a)
This problem can be reproduced with a 16 or 32 Gbps HBA by loading
qla2xxx with qlini_mode=disabled and running a high IOPS test while
triggering frequent RSCN database change events.
While analyzing the problem I discovered that even with
disable_msix_handshake forced to 0, it is not necessary to clear the
RISC interrupt from qla2xxx_msix_rsp_q_hs() (more below). So just
completely remove qla2xxx_msix_rsp_q_hs() and the logic for selecting
it, which also fixes the bug with qlini_mode=disabled.
The test below describes the justification for not needing
qla2xxx_msix_rsp_q_hs():
Force disable_msix_handshake to 0:
qla24xx_config_rings():
if (0 && (ha->fw_attributes & BIT_6) && (IS_MSIX_NACK_CAPABLE(ha)) &&
(ha->flags.msix_enabled)) {
In qla24xx_msix_rsp_q() and qla2xxx_msix_rsp_q_hs(), check:
(rd_reg_dword(®->host_status) & HSRX_RISC_INT)
Count the number of calls to each function with HSRX_RISC_INT set and
the number with HSRX_RISC_INT not set while performing some I/O.
If qla2xxx_msix_rsp_q_hs() clears the RISC interrupt (original code):
qla24xx_msix_rsp_q: 50% of calls have HSRX_RISC_INT set
qla2xxx_msix_rsp_q_hs: 5% of calls have HSRX_RISC_INT set
(# of qla2xxx_msix_rsp_q_hs interrupts) =
(# of qla24xx_msix_rsp_q interrupts) * 3
If qla2xxx_msix_rsp_q_hs() does not clear the RISC interrupt (patched
code):
qla24xx_msix_rsp_q: 100% of calls have HSRX_RISC_INT set
qla2xxx_msix_rsp_q_hs: 9% of calls have HSRX_RISC_INT set
(# of qla2xxx_msix_rsp_q_hs interrupts) =
(# of qla24xx_msix_rsp_q interrupts) * 3
In the case of the original code, qla24xx_msix_rsp_q() was seeing
HSRX_RISC_INT set only 50% of the time because qla2xxx_msix_rsp_q_hs()
was clearing it when it shouldn't have been. In the patched code,
qla24xx_msix_rsp_q() sees HSRX_RISC_INT set 100% of the time, which
makes sense if that interrupt handler needs to clear the RISC interrupt
(which it does). qla2xxx_msix_rsp_q_hs() sees HSRX_RISC_INT only 9% of
the time, which is just overlap from the other interrupt during the
high IOPS test.
Tested with SCST on:
QLE2742 FW:v9.08.02 (32 Gbps 2-port)
QLE2694L FW:v9.10.11 (16 Gbps 4-port)
QLE2694L FW:v9.08.02 (16 Gbps 4-port)
QLE2672 FW:v8.07.12 (16 Gbps 2-port)
both initiator and target mode
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Link: https://patch.msgid.link/56d378eb-14ad-49c7-bae9-c649b6c7691e@cybernetics.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
[ commit 4f6aaade2a22 upstream ]
Overview
This is the source code repository of the SCST project. SCST is a collection of Linux kernel drivers that implement SCSI target functionality. The SCST project includes:
- The SCST core in the scst/ subdirectory.
- A tool for loading, saving and modifying the SCST configuration in directory scstadmin/.
- Several SCSI target drivers in the directories iscsi-scst/, qla2x00t/, srpt/, scst_local/ and fcst/.
- User space programs in the usr/ subdirectory, e.g. fileio_tgt.
- Various documentation in the doc/ subdirectory.
Instructions for building and installing SCST are available in the INSTALL.md file.
QLogic target driver
Two QLogic target drivers are included in the SCST project.
The default driver is located in qla2x00t-32gbit directory and it supports up to 32 Gb/s FC. It is the newer one.
May anyone wish to switch back to the older driver that only supported up to
16 Gb/s adapters, it is located in qla2x00t directory. To make use of the
older driver build scst with environment variable QLA_32GBIT=no set.
Vladislav Bolkhovitin vst@vlnb.net, http://scst.sourceforge.net
Sourceforge achievements
