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Diffstat (limited to 'results/classifier/001/other/60339453')
| -rw-r--r-- | results/classifier/001/other/60339453 | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/results/classifier/001/other/60339453 b/results/classifier/001/other/60339453 new file mode 100644 index 00000000..c32e4043 --- /dev/null +++ b/results/classifier/001/other/60339453 @@ -0,0 +1,61 @@ +other: 0.776 +instruction: 0.713 +mistranslation: 0.699 +semantic: 0.662 + +[BUG] scsi: vmw_pvscsi: Boot hangs during scsi under qemu, post commit e662502b3a78 + +Hi, + +Commit e662502b3a78 ("scsi: vmw_pvscsi: Set correct residual data length"), +and its backports to stable trees, makes kernel hang during boot, when +ran as a VM under qemu with following parameters: + + -drive file=$DISKFILE,if=none,id=sda + -device pvscsi + -device scsi-hd,bus=scsi.0,drive=sda + +Diving deeper, commit e662502b3a78 + + @@ -585,7 +585,13 @@ static void pvscsi_complete_request(struct +pvscsi_adapter *adapter, + case BTSTAT_SUCCESS: + + /* + + * Commands like INQUIRY may transfer less data than + + * requested by the initiator via bufflen. Set residual + + * count to make upper layer aware of the actual amount + + * of data returned. + + */ + + scsi_set_resid(cmd, scsi_bufflen(cmd) - e->dataLen); + +assumes 'e->dataLen' is properly armed with actual num of bytes +transferred; alas qemu's hw/scsi/vmw_pvscsi.c never arms the 'dataLen' +field of the completion descriptor (kept zero). + +As a result, the residual count is set as the *entire* 'scsi_bufflen' of a +good transfer, which makes upper scsi layers repeatedly ignore this +valid transfer. + +Not properly arming 'dataLen' seems as an oversight in qemu, which needs +to be fixed. + +However, since kernels with commit e662502b3a78 (and backports) now fail +to boot under qemu's "-device pvscsi", a suggested workaround is to set +the residual count *only* if 'e->dataLen' is armed, e.g: + + @@ -588,7 +588,8 @@ static void pvscsi_complete_request(struct pvscsi_adapter +*adapter, + * count to make upper layer aware of the actual +amount + * of data returned. + */ + - scsi_set_resid(cmd, scsi_bufflen(cmd) - e->dataLen); + + if (e->dataLen) + + scsi_set_resid(cmd, scsi_bufflen(cmd) - +e->dataLen); + +in order to make kernels boot on old qemu binaries. + +Best, +Shmulik + |