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Date: Mon, 10 Jun 2024 22:31:51 -0700
From: Shradha Gupta <shradhagupta@...ux.microsoft.com>
To: Simon Horman <horms@...nel.org>
Cc: linux-hardening@...r.kernel.org, netdev@...r.kernel.org,
linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-rdma@...r.kernel.org, Colin Ian King <colin.i.king@...il.com>,
Ahmed Zaki <ahmed.zaki@...el.com>,
Pavan Chebbi <pavan.chebbi@...adcom.com>,
Souradeep Chakrabarti <schakrabarti@...ux.microsoft.com>,
Konstantin Taranov <kotaranov@...rosoft.com>,
Kees Cook <keescook@...omium.org>, Paolo Abeni <pabeni@...hat.com>,
Jakub Kicinski <kuba@...nel.org>,
Eric Dumazet <edumazet@...gle.com>,
"David S. Miller" <davem@...emloft.net>,
Dexuan Cui <decui@...rosoft.com>, Wei Liu <wei.liu@...nel.org>,
Haiyang Zhang <haiyangz@...rosoft.com>,
"K. Y. Srinivasan" <kys@...rosoft.com>,
Leon Romanovsky <leon@...nel.org>, Jason Gunthorpe <jgg@...pe.ca>,
Long Li <longli@...rosoft.com>,
Shradha Gupta <shradhagupta@...rosoft.com>
Subject: Re: [PATCH net-next v3] net: mana: Allow variable size indirection
table
On Thu, Jun 06, 2024 at 05:33:34PM +0100, Simon Horman wrote:
> On Wed, Jun 05, 2024 at 01:39:06AM -0700, Shradha Gupta wrote:
> > On Tue, Jun 04, 2024 at 10:33:49AM +0100, Simon Horman wrote:
> > > On Fri, May 31, 2024 at 08:37:41AM -0700, Shradha Gupta wrote:
> > > > Allow variable size indirection table allocation in MANA instead
> > > > of using a constant value MANA_INDIRECT_TABLE_SIZE.
> > > > The size is now derived from the MANA_QUERY_VPORT_CONFIG and the
> > > > indirection table is allocated dynamically.
> > > >
> > > > Signed-off-by: Shradha Gupta <shradhagupta@...ux.microsoft.com>
> > > > Reviewed-by: Dexuan Cui <decui@...rosoft.com>
> > > > Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.com>
> > >
> > > ...
> > >
> > > > diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
> > >
> > > ...
> > >
> > > > @@ -2344,11 +2352,33 @@ static int mana_create_vport(struct mana_port_context *apc,
> > > > return mana_create_txq(apc, net);
> > > > }
> > > >
> > > > +static int mana_rss_table_alloc(struct mana_port_context *apc)
> > > > +{
> > > > + if (!apc->indir_table_sz) {
> > > > + netdev_err(apc->ndev,
> > > > + "Indirection table size not set for vPort %d\n",
> > > > + apc->port_idx);
> > > > + return -EINVAL;
> > > > + }
> > > > +
> > > > + apc->indir_table = kcalloc(apc->indir_table_sz, sizeof(u32), GFP_KERNEL);
> > > > + if (!apc->indir_table)
> > > > + return -ENOMEM;
> > > > +
> > > > + apc->rxobj_table = kcalloc(apc->indir_table_sz, sizeof(mana_handle_t), GFP_KERNEL);
> > > > + if (!apc->rxobj_table) {
> > > > + kfree(apc->indir_table);
> > >
> > > Hi, Shradha
> > >
> > > Perhaps I am on the wrong track here, but I have some concerns
> > > about clean-up paths.
> > >
> > > Firstly. I think that apc->indir_table should be to NULL here for
> > > consistency with other clean-up paths. Or alternatively, fields of apc
> > > should not set to NULL elsewhere after being freed.
> >
> > Hi Simon,
> >
> > Thanks for the comments. This makes sense, I am planning of consistently
> > removing the NULLify from other places too as per Leon's comments.
>
> Great!
>
> > > In looking into this I noticed that mana_probe() does not call
> > > mana_remove() or return an error in the cases where mana_probe_port()
> > > or mana_attach() fail unless add_adev also fails. If so, is that
> > > intentional?
> >
> > Right, so most calls like mana_probe_port(), mana_attach() cleanup after
> > themselves in the code if there is any error. So, not having to call
> > mana_remove() in these cases in mana_probe() is intentional. But I do
> > agree that an error is returned in mana_probe() only if add_adev also
> > fails. I'll fix that too in the next version
>
> I'm not entirely sure, but perhaps that is a candidate for a separate patch.
>
> > >
> > > In any case, I would suggest as a follow-up, arranging things so that
> > > when an error occurs in a function, anything that was allocated is
> > > unwound before returning an error.
> > >
> > > I think this would make allocation/deallocation easier to reason with.
> > > And I suspect it would avoid both the need for fields of structures to
> > > be zeroed after being freed, and the need to call mana_remove() from
> > > mana_probe().
> >
> > Agreed
> > >
> > > > + return -ENOMEM;
> > > > + }
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > static void mana_rss_table_init(struct mana_port_context *apc)
> > > > {
> > > > int i;
> > > >
> > > > - for (i = 0; i < MANA_INDIRECT_TABLE_SIZE; i++)
> > > > + for (i = 0; i < apc->indir_table_sz; i++)
> > > > apc->indir_table[i] =
> > > > ethtool_rxfh_indir_default(i, apc->num_queues);
> > > > }
> > >
> > > ...
> > >
> > > > @@ -2739,11 +2772,17 @@ static int mana_probe_port(struct mana_context *ac, int port_idx,
> > > > err = register_netdev(ndev);
> > > > if (err) {
> > > > netdev_err(ndev, "Unable to register netdev.\n");
> > > > - goto reset_apc;
> > > > + goto free_indir;
> > > > }
> > > >
> > > > return 0;
> > > >
> > > > +free_indir:
> > > > + apc->indir_table_sz = 0;
> > > > + kfree(apc->indir_table);
> > > > + apc->indir_table = NULL;
> > > > + kfree(apc->rxobj_table);
> > > > + apc->rxobj_table = NULL;
> > > > reset_apc:
> > > > kfree(apc->rxqs);
> > > > apc->rxqs = NULL;
> > >
> > > nit: Not strictly related to this patch, but the reset_apc code should
> > > probably be a call to mana_cleanup_port_context() as it is the dual of
> > > mana_init_port_context() which is called earlier in mana_probe_port()
> >
> > Sure, let me do that too.
>
> FWIIW, I think it would be appropriate to put that change in a separate patch.
Fixing this and other similar changes in a different patch. Thanks
>
> > >
> > > ...
> > >
> > > > @@ -2931,6 +2972,11 @@ void mana_remove(struct gdma_dev *gd, bool suspending)
> > > > }
> > > >
> > > > unregister_netdevice(ndev);
> > > > + apc->indir_table_sz = 0;
> > > > + kfree(apc->indir_table);
> > > > + apc->indir_table = NULL;
> > > > + kfree(apc->rxobj_table);
> > > > + apc->rxobj_table = NULL;
> > >
> > > The code to free and zero indir_table_sz and indir_table appears twice
> > > in this patch. Perhaps a helper to do this, which would be the dual
> > > of mana_rss_table_alloc is in order.
> > Makes sense, will change this too.
>
> Thanks.
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