forked from luck/tmp_suning_uos_patched
505f76b306
There is a race condition in iscsi_tcp.c that may cause it to forget
that it received a R2T from the target. This race may cause a data-out
command (such as a write) to lock up. The race occurs here:
static int
iscsi_send_unsol_pdu(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
int rc;
if (tcp_ctask->xmstate & XMSTATE_UNS_HDR) {
BUG_ON(!ctask->unsol_count);
tcp_ctask->xmstate &= ~XMSTATE_UNS_HDR; <---- RACE
...
static int
iscsi_r2t_rsp(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
...
tcp_ctask->xmstate |= XMSTATE_SOL_HDR_INIT; <---- RACE
...
While iscsi_xmitworker() (called from scsi_queue_work()) is preparing to
send unsolicited data, iscsi_tcp_data_recv() (called from
tcp_read_sock()) interrupts it upon receipt of a R2T from the target.
Both contexts do read-modify-write of tcp_ctask->xmstate. Usually, gcc
on x86 will make &= and |= atomic on UP (not guaranteed of course), but
in this case iscsi_send_unsol_pdu() reads the value of xmstate before
clearing the bit, which causes gcc to read xmstate into a CPU register,
test it, clear the bit, and then store it back to memory. If the recv
interrupt happens during this sequence, then the XMSTATE_SOL_HDR_INIT
bit set by the recv interrupt will be lost, and the R2T will be
forgotten.
The patch below (against 2.6.24-rc1) converts accesses of xmstate to use
set_bit, clear_bit, and test_bit instead of |= and &=. I have tested
this patch and verified that it fixes the problem. Another possible
approach would be to hold a lock during most of the rx/tx setup and
post-processing, and drop the lock only for the actual rx/tx.
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
|
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|---|---|---|
| .. | ||
| aacraid | ||
| aic7xxx | ||
| aic7xxx_old | ||
| aic94xx | ||
| arcmsr | ||
| arm | ||
| dpt | ||
| ibmvscsi | ||
| libsas | ||
| lpfc | ||
| megaraid | ||
| pcmcia | ||
| qla2xxx | ||
| qla4xxx | ||
| sym53c8xx_2 | ||
| .gitignore | ||
| 3w-9xxx.c | ||
| 3w-9xxx.h | ||
| 3w-xxxx.c | ||
| 3w-xxxx.h | ||
| 53c700_d.h_shipped | ||
| 53c700.c | ||
| 53c700.h | ||
| 53c700.scr | ||
| a100u2w.c | ||
| a100u2w.h | ||
| a2091.c | ||
| a2091.h | ||
| a3000.c | ||
| a3000.h | ||
| a4000t.c | ||
| advansys.c | ||
| aha152x.c | ||
| aha152x.h | ||
| aha1542.c | ||
| aha1542.h | ||
| aha1740.c | ||
| aha1740.h | ||
| aic7xxx_old.c | ||
| atari_dma_emul.c | ||
| atari_NCR5380.c | ||
| atari_scsi.c | ||
| atari_scsi.h | ||
| atp870u.c | ||
| atp870u.h | ||
| blz1230.c | ||
| blz2060.c | ||
| BusLogic.c | ||
| BusLogic.h | ||
| bvme6000_scsi.c | ||
| ch.c | ||
| constants.c | ||
| cyberstorm.c | ||
| cyberstormII.c | ||
| dc395x.c | ||
| dc395x.h | ||
| dec_esp.c | ||
| dmx3191d.c | ||
| dpt_i2o.c | ||
| dpti.h | ||
| dtc.c | ||
| dtc.h | ||
| eata_generic.h | ||
| eata_pio.c | ||
| eata_pio.h | ||
| eata.c | ||
| esp_scsi.c | ||
| esp_scsi.h | ||
| fastlane.c | ||
| fd_mcs.c | ||
| fdomain.c | ||
| fdomain.h | ||
| FlashPoint.c | ||
| g_NCR5380_mmio.c | ||
| g_NCR5380.c | ||
| g_NCR5380.h | ||
| gdth_ioctl.h | ||
| gdth_proc.c | ||
| gdth_proc.h | ||
| gdth.c | ||
| gdth.h | ||
| gvp11.c | ||
| gvp11.h | ||
| hosts.c | ||
| hptiop.c | ||
| hptiop.h | ||
| ibmmca.c | ||
| ide-scsi.c | ||
| imm.c | ||
| imm.h | ||
| in2000.c | ||
| in2000.h | ||
| initio.c | ||
| initio.h | ||
| ipr.c | ||
| ipr.h | ||
| ips.c | ||
| ips.h | ||
| iscsi_tcp.c | ||
| iscsi_tcp.h | ||
| jazz_esp.c | ||
| Kconfig | ||
| lasi700.c | ||
| libiscsi.c | ||
| libsrp.c | ||
| mac_esp.c | ||
| mac_scsi.c | ||
| mac_scsi.h | ||
| mac53c94.c | ||
| mac53c94.h | ||
| Makefile | ||
| mca_53c9x.c | ||
| megaraid.c | ||
| megaraid.h | ||
| mesh.c | ||
| mesh.h | ||
| mvme16x_scsi.c | ||
| mvme147.c | ||
| mvme147.h | ||
| NCR_D700.c | ||
| NCR_D700.h | ||
| NCR_Q720.c | ||
| NCR_Q720.h | ||
| ncr53c8xx.c | ||
| ncr53c8xx.h | ||
| NCR53C9x.c | ||
| NCR53C9x.h | ||
| NCR53c406a.c | ||
| NCR5380.c | ||
| NCR5380.h | ||
| nsp32_debug.c | ||
| nsp32_io.h | ||
| nsp32.c | ||
| nsp32.h | ||
| oktagon_esp.c | ||
| oktagon_io.S | ||
| osst_detect.h | ||
| osst_options.h | ||
| osst.c | ||
| osst.h | ||
| pas16.c | ||
| pas16.h | ||
| ppa.c | ||
| ppa.h | ||
| ps3rom.c | ||
| psi_chip.h | ||
| psi240i.c | ||
| psi240i.h | ||
| ql1040_fw.h | ||
| ql1280_fw.h | ||
| ql12160_fw.h | ||
| qla1280.c | ||
| qla1280.h | ||
| qlogicfas.c | ||
| qlogicfas408.c | ||
| qlogicfas408.h | ||
| qlogicpti_asm.c | ||
| qlogicpti.c | ||
| qlogicpti.h | ||
| raid_class.c | ||
| script_asm.pl | ||
| scsi_debug.c | ||
| scsi_debug.h | ||
| scsi_devinfo.c | ||
| scsi_error.c | ||
| scsi_ioctl.c | ||
| scsi_lib_dma.c | ||
| scsi_lib.c | ||
| scsi_logging.h | ||
| scsi_module.c | ||
| scsi_netlink.c | ||
| scsi_priv.h | ||
| scsi_proc.c | ||
| scsi_sas_internal.h | ||
| scsi_scan.c | ||
| scsi_sysctl.c | ||
| scsi_sysfs.c | ||
| scsi_tgt_if.c | ||
| scsi_tgt_lib.c | ||
| scsi_tgt_priv.h | ||
| scsi_transport_api.h | ||
| scsi_transport_fc_internal.h | ||
| scsi_transport_fc.c | ||
| scsi_transport_iscsi.c | ||
| scsi_transport_sas.c | ||
| scsi_transport_spi.c | ||
| scsi_transport_srp_internal.h | ||
| scsi_transport_srp.c | ||
| scsi_typedefs.h | ||
| scsi_wait_scan.c | ||
| scsi.c | ||
| scsi.h | ||
| scsicam.c | ||
| sd.c | ||
| seagate.c | ||
| sg.c | ||
| sgiwd93.c | ||
| sim710.c | ||
| sni_53c710.c | ||
| sr_ioctl.c | ||
| sr_vendor.c | ||
| sr.c | ||
| sr.h | ||
| st_options.h | ||
| st.c | ||
| st.h | ||
| stex.c | ||
| sun_esp.c | ||
| sun3_NCR5380.c | ||
| sun3_scsi_vme.c | ||
| sun3_scsi.c | ||
| sun3_scsi.h | ||
| sun3x_esp.c | ||
| sym53c416.c | ||
| sym53c416.h | ||
| t128.c | ||
| t128.h | ||
| tmscsim.c | ||
| tmscsim.h | ||
| u14-34f.c | ||
| ultrastor.c | ||
| ultrastor.h | ||
| wd33c93.c | ||
| wd33c93.h | ||
| wd7000.c | ||
| zalon.c | ||
| zorro7xx.c | ||