Hi all,
I'm seeing crashes on powerpc with the ipr driver, which I'm fairly sure
are due to dma_need_drain being NULL.
The backtrace is:
scsi_init_io+0x1d8/0x350
scsi_queue_rq+0x7a4/0xc30
blk_mq_dispatch_rq_list+0x1b0/0x910
blk_mq_sched_dispatch_requests+0x154/0x270
__blk_mq_run_hw_queue+0xa0/0x160
__blk_mq_delay_run_hw_queue+0x244/0x250
blk_mq_sched_insert_request+0x13c/0x250
blk_execute_rq_nowait+0x88/0xb0
blk_execute_rq+0x5c/0xf0
__scsi_execute+0x10c/0x270
scsi_mode_sense+0x144/0x440
sr_probe+0x2e8/0x810
really_probe+0x12c/0x580
driver_probe_device+0x88/0x170
device_driver_attach+0x11c/0x130
__driver_attach+0xac/0x190
bus_for_each_dev+0xa8/0x130
driver_attach+0x34/0x50
bus_add_driver+0x170/0x2b0
driver_register+0xb4/0x1c0
scsi_register_driver+0x2c/0x40
init_sr+0x4c/0x80
do_one_initcall+0x60/0x2b0
kernel_init_freeable+0x2e0/0x3a0
kernel_init+0x2c/0x148
ret_from_kernel_thread+0x5c/0x74
And looking at the disassembly I think it's coming from:
static inline bool scsi_cmd_needs_dma_drain(struct scsi_device *sdev,
struct request *rq)
{
return sdev->dma_drain_len && blk_rq_is_passthrough(rq) &&
!op_is_write(req_op(rq)) &&
sdev->host->hostt->dma_need_drain(rq);
^^^^^^^^^^^^^^
}
Bisect agrees:
# first bad commit: [cc97923a5bccc776851c242b61015faf288d5c22] block: move dma drain handling to scsi
And looking at ipr.c, it constructs its scsi_host_template manually,
without using any of the macros that end up calling __ATA_BASE_SHT,
which populates dma_need_drain.
The obvious fix below works, the system boots and seems to be operating
normally, but I don't know enough (anything) about SCSI to say if it's
actually the correct fix.
cheers
diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index 7d77997d26d4..7d86f4ca266c 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -6731,6 +6731,7 @@ static struct scsi_host_template driver_template = {
.compat_ioctl = ipr_ioctl,
#endif
.queuecommand = ipr_queuecommand,
+ .dma_need_drain = ata_scsi_dma_need_drain,
.eh_abort_handler = ipr_eh_abort,
.eh_device_reset_handler = ipr_eh_dev_reset,
.eh_host_reset_handler = ipr_eh_host_reset,
