Re: [PATCH] simscsi breakage in __scsi_alloc_queue()

[James Bottomley <jbottomley@xxxxxxxxxxxxx>]

On Fri, 2012-05-04 at 04:53 +0100, Al Viro wrote:
> With the current mainline we end up oopsing in __scsi_alloc_queue(), since
> host->dma_dev is left NULL.  I'm not sure if this is the right fix, but
> it gives the behaviour equivalent to what we used to have before
> commit 6f381fa344911d5a234b13574433cf23036f9467 ([SCSI] scsi_lib: use
> correct DMA device in __scsi_alloc_queue).  And with that applied the
> damn thing appears to work correctly...
> 
> Current mainline barfs on dma_set_seg_boundary(dev, shost->dma_boundary),
> since dev ends up being NULL.  AFAICS, the same problem affects any
> driver that does scsi_add_host(host, NULL) and there are other such
> beasts as well, so they probably also need fixing...
> 
> Again, I'm not sure that this is the right way to deal with that and I'd
> prefer to have it reviewed by SCSI folks before it goes into the tree.
> 
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> ---
> diff --git a/arch/ia64/hp/sim/simscsi.c b/arch/ia64/hp/sim/simscsi.c
> index 331de72..fe2b4d0 100644
> --- a/arch/ia64/hp/sim/simscsi.c
> +++ b/arch/ia64/hp/sim/simscsi.c
> @@ -13,6 +13,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/kernel.h>
>  #include <linux/timer.h>
> +#include <linux/platform_device.h>
>  #include <asm/irq.h>
>  #include "hpsim_ssc.h"
>  
> @@ -358,7 +359,7 @@ simscsi_init(void)
>  	if (!host)
>  		return -ENOMEM;
>  
> -	error = scsi_add_host(host, NULL);
> +	error = scsi_add_host_with_dma(host, NULL, &platform_bus);

It's the right fix, but it's not general enough.  This should make sure
none of the legacy bus devices oops:

James

---

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 351dc0b..a3a056a 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -218,6 +218,9 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
 
 	if (!shost->shost_gendev.parent)
 		shost->shost_gendev.parent = dev ? dev : &platform_bus;
+	if (!dma_dev)
+		dma_dev = shost->shost_gendev.parent;
+
 	shost->dma_dev = dma_dev;
 
 	error = device_add(&shost->shost_gendev);

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