Mike Christie wrote: > On Sun, 2006-10-01 at 15:40 -0500, James Bottomley wrote: >> On Sun, 2006-10-01 at 22:13 +0200, Andi Kleen wrote: >>> GFP_DMA in general is deprecated and should be replaced by appropiate >>> dma_alloc_coherent() >> Um, no it shouldn't. >> >> All of the places where we use GFP_DMA are because we might be >> addressing an ISA card or other strange mask limited card (gated usually >> by unchecked_isa_dma). However, what is wanted in every case is >> ordinary memory, not coherent memory. They can't simply be replaced >> with dma_alloc_coherent because >> >> a) it will waste memory for platforms that only do it in page size >> multiples >> b) It will fail on platforms that can't do it at all. >> >> Coherent memory is really only for device drivers to use in mailboxes >> and shared ring buffers. >> >>> or similar. And I can't imagine any modern systems still need them, and for >>> the few still non CONFIG_BROKEN ISA drivers maybe some other way can be found? >>> And do they really require the mid layer data structures to be GFP_DMA too? >> Well, it's the "or similar" that's still the problem. All they need is >> ordinary memory which respects the device mask (then I can get rid of >> the unchecked_isa_dma flag as well). >> >> One could argue, I suppose, that when we get every SCSI path to go via >> sg, then the block layer will bounce this for us, and we don't need to >> worry at all. > > > I think we might just need the blk_map_kern users now. For the async Oops, I just meant for the ULDs, scsi-ml, and block layer drivers. I did not look at if/when the LLDs inject commands directly to their queuecommand. > execute I added the bounce code already and the block SG_IO has it > atleady. I think the blk_map_kern bounce code got dropped because we > thought the correct gfp_t would be passed in. But I think all we need is > the patch below and all the paths are take care of. The patch is not > tested. Patch was made against scsi-misc. > > The last place that is sending non sg commands may just be md/dm-emc.c > but that is is just waiting on alasdair to take some patches that fix > that and a bunch of junk in there including adding bounce support. If > the patch below is ok though and dm-emc finally gets converted then it > will have sg and bonce buffer support. > > > > Signed-off-by: Mike Christie <michaelc@xxxxxxxxxxx> > > diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c > index 9c3a06b..e58b43a 100644 > --- a/block/ll_rw_blk.c > +++ b/block/ll_rw_blk.c > @@ -2533,6 +2533,7 @@ int blk_rq_map_kern(request_queue_t *q, > rq->bio = rq->biotail = bio; > blk_rq_bio_prep(q, rq, bio); > > + blk_queue_bounce(q, &rq->bio); > rq->buffer = rq->data = NULL; > rq->data_len = len; > return 0; > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > diff --git a/fs/bio.c b/fs/bio.c > > > - > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
