Re: 2.4.21-pre3 kernel crash

Benjamin Herrenschmidt
2003-01-27T19:10:37Z

Ok, after a second look, 2.4.20 seem correct. Here's a patch against 2.4.21-pre3
doing it like 2.4.20 did.

Let me know if it helps

===== drivers/ide/ide-dma.c 1.7 vs edited =====
--- 1.7/drivers/ide/ide-dma.c Tue Dec 10 21:21:57 2002
+++ edited/drivers/ide/ide-dma.c Mon Jan 27 20:17:35 2003
@@ -249,36 +249,54 @@
{
struct buffer_head *bh;
struct scatterlist *sg = hwif->sg_table;
+ unsigned long lastdataend = ~0UL;
int nents = 0;

if (hwif->sg_dma_active)
BUG();

+ hwif->sg_dma_direction = ddir;
+
bh = rq->bh;
do {
- unsigned char *virt_addr = bh->b_data;
- unsigned int size = bh->b_size;
+ struct scatterlist *sge;
+
+ /*
+ * continue segment from before?
+ */
+ if (bh_phys(bh) == lastdataend) {
+ sg[nents - 1].length += bh->b_size;
+ lastdataend += bh->b_size;
+ continue;
+ }

+ /*
+ * start new segment
+ */
if (nents >= PRD_ENTRIES)
return 0;

- while ((bh = bh->b_reqnext) != NULL) {
- if ((virt_addr + size) != (unsigned char *) bh->b_data)
- break;
- size += bh->b_size;
+ sge = &sg[nents];
+ memset(sge, 0, sizeof(*sge));
+
+ if (bh->b_page) {
+ sge->page = bh->b_page;
+ sge->offset = bh_offset(bh);
+ } else {
+ if (((unsigned long) bh->b_data) < PAGE_SIZE)
+ BUG();
+
+ sge->address = bh->b_data;
}
- memset(&sg[nents], 0, sizeof(*sg));
- sg[nents].address = virt_addr;
- sg[nents].length = size;
- if(size == 0)
- BUG();
+
+ sge->length = bh->b_size;
+ lastdataend = bh_phys(bh) + bh->b_size;
nents++;
- } while (bh != NULL);
+ } while ((bh = bh->b_reqnext) != NULL);

if(nents == 0)
BUG();

- hwif->sg_dma_direction = ddir;
return pci_map_sg(hwif->pci_dev, sg, nents, ddir);
}