Re: BAD_SG_DMA panic in aha1542

Alan Cox
2007-04-27T22:10:59Z

> As before, no problems using the sda hard disk (which is the boot drive):
> everything works reliably until I touch the cdrom drive.

A little quiet contemplation and gnome number 387 suggests trying the following
(and providing more detailed information such as the last message printed before
the DMA message). Stuff a BUG() before the panic in BAD_DMA (aha1542.c) if needed
to get a good trace.

Please report success/failure/change.

--- drivers/scsi/sr_ioctl.c~ 2007-04-27 22:53:33.885035256 +0100
+++ drivers/scsi/sr_ioctl.c 2007-04-27 22:53:33.885035256 +0100
@@ -187,9 +187,10 @@
struct scsi_sense_hdr sshdr;
int result, err = 0, retries = 0;
struct request_sense *sense = cgc->sense;
-
+ void *zebedee = cgc->buffer;
+
SDev = cd->device;
-
+
if (!sense) {
sense = kmalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
if (!sense) {
@@ -197,7 +198,22 @@
goto out;
}
}
-
+
+ if (cgc->buflen && cd->device->host->unchecked_isa_dma) {
+ switch(cgc->data_direction) {
+ case DMA_NONE:
+ break;
+ case DMA_FROM_DEVICE:
+ case DMA_TO_DEVICE: /* Boing!!!! said Zebedee */
+ zebedee = kmalloc(cgc->buflen, GFP_KERNEL|GFP_DMA);
+ if (zebedee ==NULL) {
+ err = -ENOMEM;
+ goto out;
+ }
+ }
+ if (cgc->data_direction == DMA_TO_DEVICE)
+ memcpy(zebedee, cgc->buffer, cgc->buflen);
+ }
retry:
if (!scsi_block_when_processing_errors(SDev)) {
err = -ENODEV;
@@ -206,10 +222,13 @@

memset(sense, 0, sizeof(*sense));
result = scsi_execute(SDev, cgc->cmd, cgc->data_direction,
- cgc->buffer, cgc->buflen, (char *)sense,
+ zebedee, cgc->buflen, (char *)sense,
cgc->timeout, IOCTL_RETRIES, 0);

scsi_normalize_sense((char *)sense, sizeof(*sense), &sshdr);
+
+ if (zebedeee != cgc->buffer && cgc->data_direction == DMA_FROM_DEVICE)
+ memcpy(cgc->buffer, zebedee, cgc->buflen);

/* Minimal error checking. Ignore cases we know about, and report the rest. */
if (driver_byte(result) != 0) {