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Date:   Mon, 29 May 2023 04:17:33 -0700
From:   Shradha Gupta <shradhagupta@linux.microsoft.com>
To:     Praveen Kumar <kumarpraveen@linux.microsoft.com>
Cc:     linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
        netdev@vger.kernel.org, Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        Long Li <longli@microsoft.com>,
        Michael Kelley <mikelley@microsoft.com>,
        "David S. Miller" <davem@davemloft.net>,
        Steen Hegelund <steen.hegelund@microchip.com>,
        Simon Horman <simon.horman@corigine.com>
Subject: Re: [PATCH v3] hv_netvsc: Allocate rx indirection table size
 dynamically
Message-ID: <20230529111733.GA21447@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
References: <1685080949-18316-1-git-send-email-shradhagupta@linux.microsoft.com>
 <5fc413e5-77d2-814d-250a-7ddf8eb6d6ad@linux.microsoft.com>
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On Mon, May 29, 2023 at 03:09:49PM +0530, Praveen Kumar wrote:
> On 5/26/2023 11:32 AM, Shradha Gupta wrote:
> > Allocate the size of rx indirection table dynamically in netvsc
> > from the value of size provided by OID_GEN_RECEIVE_SCALE_CAPABILITIES
> > query instead of using a constant value of ITAB_NUM.
> > 
> > Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
> > Tested-on: Ubuntu22 (azure VM, SKU size: Standard_F72s_v2)
> > Testcases:
> > 1. ethtool -x eth0 output
> > 2. LISA testcase:PERF-NETWORK-TCP-THROUGHPUT-MULTICONNECTION-NTTTCP-Synthetic
> > 3. LISA testcase:PERF-NETWORK-TCP-THROUGHPUT-MULTICONNECTION-NTTTCP-SRIOV
> > 
> > ---
> > Changes in v3:
> >  * Changed the data type of rx_table_sz to u32
> >  * Moved the rx indirection table free to rndis_filter_device_remove()
> >  * Device add will fail with error if not enough memory is available
> >  * Changed kzmalloc to kcalloc as suggested in checkpatch script
> >  * Removed redundant log if memory allocation failed.
> > ---
> >  drivers/net/hyperv/hyperv_net.h   |  5 ++++-
> >  drivers/net/hyperv/netvsc_drv.c   | 10 ++++++----
> >  drivers/net/hyperv/rndis_filter.c | 27 +++++++++++++++++++++++----
> >  3 files changed, 33 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
> > index dd5919ec408b..c40868f287a9 100644
> > --- a/drivers/net/hyperv/hyperv_net.h
> > +++ b/drivers/net/hyperv/hyperv_net.h
> > @@ -74,6 +74,7 @@ struct ndis_recv_scale_cap { /* NDIS_RECEIVE_SCALE_CAPABILITIES */
> >  #define NDIS_RSS_HASH_SECRET_KEY_MAX_SIZE_REVISION_2   40
> >  
> >  #define ITAB_NUM 128
> > +#define ITAB_NUM_MAX 256
> >  
> >  struct ndis_recv_scale_param { /* NDIS_RECEIVE_SCALE_PARAMETERS */
> >  	struct ndis_obj_header hdr;
> > @@ -1034,7 +1035,9 @@ struct net_device_context {
> >  
> >  	u32 tx_table[VRSS_SEND_TAB_SIZE];
> >  
> > -	u16 rx_table[ITAB_NUM];
> > +	u16 *rx_table;
> > +
> > +	u32 rx_table_sz;
> >  
> >  	/* Ethtool settings */
> >  	u8 duplex;
> > diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> > index 0103ff914024..3ba3c8fb28a5 100644
> > --- a/drivers/net/hyperv/netvsc_drv.c
> > +++ b/drivers/net/hyperv/netvsc_drv.c
> > @@ -1747,7 +1747,9 @@ static u32 netvsc_get_rxfh_key_size(struct net_device *dev)
> >  
> >  static u32 netvsc_rss_indir_size(struct net_device *dev)
> >  {
> > -	return ITAB_NUM;
> > +	struct net_device_context *ndc = netdev_priv(dev);
> > +
> > +	return ndc->rx_table_sz;
> >  }
> >  
> >  static int netvsc_get_rxfh(struct net_device *dev, u32 *indir, u8 *key,
> > @@ -1766,7 +1768,7 @@ static int netvsc_get_rxfh(struct net_device *dev, u32 *indir, u8 *key,
> >  
> >  	rndis_dev = ndev->extension;
> >  	if (indir) {
> > -		for (i = 0; i < ITAB_NUM; i++)
> > +		for (i = 0; i < ndc->rx_table_sz; i++)
> >  			indir[i] = ndc->rx_table[i];
> >  	}
> >  
> > @@ -1792,11 +1794,11 @@ static int netvsc_set_rxfh(struct net_device *dev, const u32 *indir,
> >  
> >  	rndis_dev = ndev->extension;
> >  	if (indir) {
> > -		for (i = 0; i < ITAB_NUM; i++)
> > +		for (i = 0; i < ndc->rx_table_sz; i++)
> >  			if (indir[i] >= ndev->num_chn)
> >  				return -EINVAL;
> >  
> > -		for (i = 0; i < ITAB_NUM; i++)
> > +		for (i = 0; i < ndc->rx_table_sz; i++)
> >  			ndc->rx_table[i] = indir[i];
> >  	}
> >  
> > diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
> > index eea777ec2541..dc7b9b326690 100644
> > --- a/drivers/net/hyperv/rndis_filter.c
> > +++ b/drivers/net/hyperv/rndis_filter.c
> > @@ -21,6 +21,7 @@
> >  #include <linux/rtnetlink.h>
> >  #include <linux/ucs2_string.h>
> >  #include <linux/string.h>
> > +#include <linux/slab.h>
> >  
> >  #include "hyperv_net.h"
> >  #include "netvsc_trace.h"
> > @@ -927,7 +928,7 @@ static int rndis_set_rss_param_msg(struct rndis_device *rdev,
> >  	struct rndis_set_request *set;
> >  	struct rndis_set_complete *set_complete;
> >  	u32 extlen = sizeof(struct ndis_recv_scale_param) +
> > -		     4 * ITAB_NUM + NETVSC_HASH_KEYLEN;
> > +		     4 * ndc->rx_table_sz + NETVSC_HASH_KEYLEN;
> >  	struct ndis_recv_scale_param *rssp;
> >  	u32 *itab;
> >  	u8 *keyp;
> > @@ -953,7 +954,7 @@ static int rndis_set_rss_param_msg(struct rndis_device *rdev,
> >  	rssp->hashinfo = NDIS_HASH_FUNC_TOEPLITZ | NDIS_HASH_IPV4 |
> >  			 NDIS_HASH_TCP_IPV4 | NDIS_HASH_IPV6 |
> >  			 NDIS_HASH_TCP_IPV6;
> > -	rssp->indirect_tabsize = 4*ITAB_NUM;
> > +	rssp->indirect_tabsize = 4 * ndc->rx_table_sz;
> >  	rssp->indirect_taboffset = sizeof(struct ndis_recv_scale_param);
> >  	rssp->hashkey_size = NETVSC_HASH_KEYLEN;
> >  	rssp->hashkey_offset = rssp->indirect_taboffset +
> > @@ -961,7 +962,7 @@ static int rndis_set_rss_param_msg(struct rndis_device *rdev,
> >  
> >  	/* Set indirection table entries */
> >  	itab = (u32 *)(rssp + 1);
> > -	for (i = 0; i < ITAB_NUM; i++)
> > +	for (i = 0; i < ndc->rx_table_sz; i++)
> >  		itab[i] = ndc->rx_table[i];
> >  
> >  	/* Set hask key values */
> > @@ -1548,6 +1549,17 @@ struct netvsc_device *rndis_filter_device_add(struct hv_device *dev,
> >  	if (ret || rsscap.num_recv_que < 2)
> >  		goto out;
> >  
> > +	if (rsscap.num_indirect_tabent &&
> > +	    rsscap.num_indirect_tabent <= ITAB_NUM_MAX)
> > +		ndc->rx_table_sz = rsscap.num_indirect_tabent;
> > +	else
> > +		ndc->rx_table_sz = ITAB_NUM;
> > +
> > +	ndc->rx_table = kcalloc(ndc->rx_table_sz, sizeof(u16),
> > +				GFP_KERNEL);
> > +	if (!ndc->rx_table)
> > +		goto err_dev_remv;
> > +
> >  	/* This guarantees that num_possible_rss_qs <= num_online_cpus */
> >  	num_possible_rss_qs = min_t(u32, num_online_cpus(),
> >  				    rsscap.num_recv_que);
> > @@ -1558,7 +1570,7 @@ struct netvsc_device *rndis_filter_device_add(struct hv_device *dev,
> >  	net_device->num_chn = min(net_device->max_chn, device_info->num_chn);
> >  
> >  	if (!netif_is_rxfh_configured(net)) {
> > -		for (i = 0; i < ITAB_NUM; i++)
> > +		for (i = 0; i < ndc->rx_table_sz; i++)
> >  			ndc->rx_table[i] = ethtool_rxfh_indir_default(
> >  						i, net_device->num_chn);
> >  	}
> > @@ -1596,11 +1608,18 @@ void rndis_filter_device_remove(struct hv_device *dev,
> >  				struct netvsc_device *net_dev)
> >  {
> >  	struct rndis_device *rndis_dev = net_dev->extension;
> > +	struct net_device *net = hv_get_drvdata(dev);
> > +	struct net_device_context *ndc = netdev_priv(net);
> >  
> >  	/* Halt and release the rndis device */
> >  	rndis_filter_halt_device(net_dev, rndis_dev);
> >  
> >  	netvsc_device_remove(dev);
> 
> Shouldn't the netvsc_device_remove be called post table cleanup ? or better, the cleanup should happen as part of netvsc_device_remove operation ? This looks a bug to me as with remove operation, we already cleaned up the device and the association between context and device is removed.

The netvsc_device_remove() function is responsible for cleaning up/removing the netvsc_device structures upon events like remove/suspend. The net_device and net_device_context structures(where the rx indirection table exists) remain untouched in netvsc_device_remove(). They(net_device, net_device_context) only get cleaned up in netvsc_remove(). So, the netvsc_device_remove() should not affect the cleanup for the rx indirection table, that we did.

> > +
> > +	ndc->rx_table_sz = 0;
> > +	kfree(ndc->rx_table);
> > +	ndc->rx_table = NULL;
> > +
> >  }
> >  
> >  int rndis_filter_open(struct netvsc_device *nvdev)