2.6.18 bug in gdth.c [solved]

["Jerome Borsboom" <j.borsboom@erasmusmc.nl>]

Recent changes in the gdth.c driver introduced an 'unable to handle 
kernel paging request' bug. The offending change seems to be 
following change in 'gdth_fill_raw_cmd':

@@ -3022,7 +3148,7 @@ #ifdef GDTH_STATISTICS
             }
#endif
-        } else {
+        } else if (scp->request_bufflen) {
             scp->SCp.Status = GDTH_MAP_SINGLE;
             scp->SCp.Message = PCI_DMA_BIDIRECTIONAL;
             page = virt_to_page(scp->request_buffer);

Reverting this line, make the driver stable again. My hypothesis is 
that when scp->request_bufflen is 0, then cmdp->u.raw.sg_ranz will 
not be assigned which makes the subsequent ha->cmd_len calculation 
misbehave. When you compare gdth_fill_raw_cmd with 
gdth_fill_cache_cmd, then in the latter function cmdp- 
>u.cache.sg_canz IS assigned before the conditional 'if (scp- 
>use_sg)...'


Jerome Borsboom
-----------------------------
Dr.ir. Jerome Borsboom, Ph.D.
Biomedical Engineering
Erasmus MC
Room Ee2302
Dr. Molewaterplein 50
3015 GE Rotterdam
the Netherlands
Tel:  +31 10 408 7474
Fax: + 31 10 408 9445


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