Interesting, yet stupid test case

[Sean Bruno]

On Mon, 2013-08-19 at 14:54 -0400, Mark Johnston wrote:
> On Mon, Aug 19, 2013 at 10:44:54AM -0700, Sean Bruno wrote:
> > Was able to get mfi to detonate (via CAM) today on stable/9 
> > 
> > At the loader prompt, physically remove some amount of drives (in my
> > case drives 0-5, as 6-11 are my zroot).  Boot up into single user via
> > boot -s
> > 
> > System will attempt to process all the events in the controller on boot
> > up and die violently.  :-)
> 
> Yuck. :(
> 
> I think we're not supposed to drop the SIM lock before calling
> xpt_rescan(); the other drivers I've looked at don't do this at least.
> We're also unnecessarily dropping the mfi lock around the call to
> xpt_alloc_ccb_nowait().
> 
> I think the following (untested) patch should help. I can try testing it
> myself later if I can get a hold of some equipment at work (might take a
> few days).
> 
> Thanks,
> -Mark
> 
Yup, this fixes the panic on startup on a Dell H310 if I pull 3 disks
out at the loader prompt and then continue to boot.

Sean



> Index: mfi_cam.c
> ===================================================================
> --- mfi_cam.c	(revision 254539)
> +++ mfi_cam.c	(working copy)
> @@ -307,10 +307,10 @@
>  		return;
>  	}
>  	camsc->state = MFIP_STATE_RESCAN;
> -	mtx_unlock(&sc->mfi_io_lock);
>  
>  	ccb = xpt_alloc_ccb_nowait();
>  	if (ccb == NULL) {
> +		mtx_unlock(&sc->mfi_io_lock);
>  		device_printf(sc->mfi_dev,
>  		    "Cannot allocate ccb for bus rescan.\n");
>  		return;
> @@ -317,7 +317,6 @@
>  	}
>  
>  	sim = camsc->sim;
> -	mtx_lock(&sc->mfi_io_lock);
>  	if (xpt_create_path(&ccb->ccb_h.path, NULL, cam_sim_path(sim),
>  	    tid, CAM_LUN_WILDCARD) != CAM_REQ_CMP) {
>  		xpt_free_ccb(ccb);
> @@ -326,11 +325,8 @@
>  		    "Cannot create path for bus rescan.\n");
>  		return;
>  	}
> -	mtx_unlock(&sc->mfi_io_lock);
> -
>  	xpt_rescan(ccb);
>  
> -	mtx_lock(&sc->mfi_io_lock);
>  	camsc->state = MFIP_STATE_NONE;
>  	mtx_unlock(&sc->mfi_io_lock);
>  }

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