Re: [PATCHv2 1/1] IB/srp: fix invalid indirect_sg_entries parameter value

[Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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On Wed, 2017-01-04 at 15:09 +0000, Bart Van Assche wrote:
> On Wed, 2017-01-04 at 15:59 +0200, Max Gurtovoy wrote:
> > 
> > From: Israel Rukshin <israelr-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > 
> > After setting indirect_sg_entries module_param to huge value (e.g
> > 500,000),
> > srp_alloc_req_data() fails to allocate indirect descriptors for the
> > request
> > ring (kmalloc fails). This commit enforces the maximum value of
> > indirect_sg_entries
> > to be SG_MAX_SEGMENTS as signified in module param description.
> > 
> > Signed-off-by: Israel Rukshin <israelr-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > Signed-off-by: Max Gurtovoy <maxg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> > ---
> >  drivers/infiniband/ulp/srp/ib_srp.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/drivers/infiniband/ulp/srp/ib_srp.c
> > b/drivers/infiniband/ulp/srp/ib_srp.c
> > index 0f67cf9..79bf484 100644
> > --- a/drivers/infiniband/ulp/srp/ib_srp.c
> > +++ b/drivers/infiniband/ulp/srp/ib_srp.c
> > @@ -3699,6 +3699,12 @@ static int __init srp_init_module(void)
> >  		indirect_sg_entries = cmd_sg_entries;
> >  	}
> >  
> > +	if (indirect_sg_entries > SG_MAX_SEGMENTS) {
> > +		pr_warn("Clamping indirect_sg_entries to %u\n",
> > +			SG_MAX_SEGMENTS);
> > +		indirect_sg_entries = SG_MAX_SEGMENTS;
> > +	}
> > +
> >  	srp_remove_wq = create_workqueue("srp_remove");
> >  	if (!srp_remove_wq) {
> >  		ret = -ENOMEM;
> 
> Thanks!
> 
> Reviewed-by: Bart Van Assche <bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org>

This patch is a fix patch and should have been tagged as such.
 However, the proper tagging is complicated by the fact that the
SG_MAX_SEGMENTS was originally named SCSI_MAX_SG_CHAIN_SEGMENTS.  The
fix applies all the way back to the first patch to enable SG segments
in the srp driver, but you will need a different patch for the kernels
prior to the rename.  For this patch, I've added the following tags and
applied the patch:

Fixes: 65e8617fba17 (scsi: rename SCSI_MAX_{SG, SG_CHAIN}_SEGMENTS)
Fixes: c07d424d6118 (IB/srp: add support for indirect tables that don't
fit in SRP_CMD)
Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org # 4.7+

Someone should write a patch for the earlier kernels and submit it
directly to stable@ with the patch flagged for application on kernels
from 2.6.39 to 4.6.  The upstream hash for the fix to mainline is:

commit 0a475ef4226e305bdcffe12b401ca1eab06c4913
Author: Israel Rukshin <israelr-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Date:   Wed Jan 4 15:59:37 2017 +0200

    IB/srp: fix invalid indirect_sg_entries parameter value

-- 
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
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