Re: [PATCH net-next v1] xen-netback: make copy batch size configurable
On Mon, Nov 13, 2017 at 04:39:09PM +, Paul Durrant wrote:
> > -Original Message-
> > From: Joao Martins [mailto:joao.m.mart...@oracle.com]
> > Sent: 13 November 2017 16:34
> > To: Paul Durrant
> > Cc: netdev@vger.kernel.org; Wei Liu ; xen-
> > de...@lists.xenproject.org
> > Subject: Re: [PATCH net-next v1] xen-netback: make copy batch size
> > configurable
> >
> > On Mon, Nov 13, 2017 at 11:58:03AM +, Paul Durrant wrote:
> > > On Mon, Nov 13, 2017 at 11:54:00AM +, Joao Martins wrote:
> > > > On 11/13/2017 10:33 AM, Paul Durrant wrote:
> > > > > On 11/10/2017 19:35 PM, Joao Martins wrote:
> >
> > [snip]
> >
> > > > >> diff --git a/drivers/net/xen-netback/rx.c
> > > > >> b/drivers/net/xen-netback/rx.c
> > > > >> index b1cf7c6f407a..793a85f61f9d 100644
> > > > >> --- a/drivers/net/xen-netback/rx.c
> > > > >> +++ b/drivers/net/xen-netback/rx.c
> > > > >> @@ -168,11 +168,14 @@ static void xenvif_rx_copy_add(struct
> > > > >> xenvif_queue *queue,
> > > > >> struct xen_netif_rx_request *req,
> > > > >> unsigned int offset, void *data, size_t
> > > > >> len)
> > > > >> {
> > > > >> +unsigned int batch_size;
> > > > >> struct gnttab_copy *op;
> > > > >> struct page *page;
> > > > >> struct xen_page_foreign *foreign;
> > > > >>
> > > > >> -if (queue->rx_copy.num == COPY_BATCH_SIZE)
> > > > >> +batch_size = min(xenvif_copy_batch_size, queue->rx_copy.size);
> > > > >
> > > > > Surely queue->rx_copy.size and xenvif_copy_batch_size are always
> > > > > identical? Why do you need this statement (and hence stack variable)?
> > > > >
> > > > This statement was to allow to be changed dynamically and would
> > > > affect all newly created guests or running guests if value happened
> > > > to be smaller than initially allocated. But I suppose I should make
> > > > behaviour more consistent with the other params we have right now
> > > > and just look at initially allocated one `queue->rx_copy.batch_size` ?
> > >
> > > Yes, that would certainly be consistent but I can see value in
> > > allowing it to be dynamically tuned, so perhaps adding some re-allocation
> > > code to allow the batch to be grown as well as shrunk might be nice.
> >
> > The shrink one we potentially risk losing data, so we need to gate the
> > reallocation whenever `rx_copy.num` is less than the new requested
> > batch. Worst case means guestrx_thread simply uses the initial
> > allocated value.
>
> Can't you just re-alloc immediately after the flush (when num is
> guaranteed to be zero)?
/facepalm
Yes, after the flush should make things much simpler.
Joao
RE: [PATCH net-next v1] xen-netback: make copy batch size configurable
> -Original Message-
> From: Joao Martins [mailto:joao.m.mart...@oracle.com]
> Sent: 13 November 2017 16:34
> To: Paul Durrant
> Cc: netdev@vger.kernel.org; Wei Liu ; xen-
> de...@lists.xenproject.org
> Subject: Re: [PATCH net-next v1] xen-netback: make copy batch size
> configurable
>
> On Mon, Nov 13, 2017 at 11:58:03AM +, Paul Durrant wrote:
> > On Mon, Nov 13, 2017 at 11:54:00AM +, Joao Martins wrote:
> > > On 11/13/2017 10:33 AM, Paul Durrant wrote:
> > > > On 11/10/2017 19:35 PM, Joao Martins wrote:
>
> [snip]
>
> > > >> diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-
> netback/rx.c
> > > >> index b1cf7c6f407a..793a85f61f9d 100644
> > > >> --- a/drivers/net/xen-netback/rx.c
> > > >> +++ b/drivers/net/xen-netback/rx.c
> > > >> @@ -168,11 +168,14 @@ static void xenvif_rx_copy_add(struct
> > > >> xenvif_queue *queue,
> > > >> struct xen_netif_rx_request *req,
> > > >> unsigned int offset, void *data, size_t
> > > >> len)
> > > >> {
> > > >> + unsigned int batch_size;
> > > >>struct gnttab_copy *op;
> > > >>struct page *page;
> > > >>struct xen_page_foreign *foreign;
> > > >>
> > > >> - if (queue->rx_copy.num == COPY_BATCH_SIZE)
> > > >> + batch_size = min(xenvif_copy_batch_size, queue-
> >rx_copy.size);
> > > >
> > > > Surely queue->rx_copy.size and xenvif_copy_batch_size are always
> > > > identical? Why do you need this statement (and hence stack variable)?
> > > >
> > > This statement was to allow to be changed dynamically and would
> > > affect all newly created guests or running guests if value happened
> > > to be smaller than initially allocated. But I suppose I should make
> > > behaviour more consistent with the other params we have right now
> > > and just look at initially allocated one `queue->rx_copy.batch_size` ?
> >
> > Yes, that would certainly be consistent but I can see value in
> > allowing it to be dynamically tuned, so perhaps adding some re-allocation
> > code to allow the batch to be grown as well as shrunk might be nice.
>
> The shrink one we potentially risk losing data, so we need to gate the
> reallocation whenever `rx_copy.num` is less than the new requested
> batch. Worst case means guestrx_thread simply uses the initial
> allocated value.
Can't you just re-alloc immediately after the flush (when num is guaranteed to
be zero)?
Paul
Re: [PATCH net-next v1] xen-netback: make copy batch size configurable
On Mon, Nov 13, 2017 at 11:58:03AM +, Paul Durrant wrote:
> On Mon, Nov 13, 2017 at 11:54:00AM +, Joao Martins wrote:
> > On 11/13/2017 10:33 AM, Paul Durrant wrote:
> > > On 11/10/2017 19:35 PM, Joao Martins wrote:
[snip]
> > >> diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c
> > >> index b1cf7c6f407a..793a85f61f9d 100644
> > >> --- a/drivers/net/xen-netback/rx.c
> > >> +++ b/drivers/net/xen-netback/rx.c
> > >> @@ -168,11 +168,14 @@ static void xenvif_rx_copy_add(struct
> > >> xenvif_queue *queue,
> > >> struct xen_netif_rx_request *req,
> > >> unsigned int offset, void *data, size_t
> > >> len)
> > >> {
> > >> +unsigned int batch_size;
> > >> struct gnttab_copy *op;
> > >> struct page *page;
> > >> struct xen_page_foreign *foreign;
> > >>
> > >> -if (queue->rx_copy.num == COPY_BATCH_SIZE)
> > >> +batch_size = min(xenvif_copy_batch_size, queue->rx_copy.size);
> > >
> > > Surely queue->rx_copy.size and xenvif_copy_batch_size are always
> > > identical? Why do you need this statement (and hence stack variable)?
> > >
> > This statement was to allow to be changed dynamically and would
> > affect all newly created guests or running guests if value happened
> > to be smaller than initially allocated. But I suppose I should make
> > behaviour more consistent with the other params we have right now
> > and just look at initially allocated one `queue->rx_copy.batch_size` ?
>
> Yes, that would certainly be consistent but I can see value in
> allowing it to be dynamically tuned, so perhaps adding some re-allocation
> code to allow the batch to be grown as well as shrunk might be nice.
The shrink one we potentially risk losing data, so we need to gate the
reallocation whenever `rx_copy.num` is less than the new requested
batch. Worst case means guestrx_thread simply uses the initial
allocated value.
Anyhow, something like the below scissored diff (on top of your comments):
diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index a165a4123396..8e4eaf3a507d 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -359,6 +359,7 @@ irqreturn_t xenvif_ctrl_irq_fn(int irq, void *data);
void xenvif_rx_action(struct xenvif_queue *queue);
void xenvif_rx_queue_tail(struct xenvif_queue *queue, struct sk_buff *skb);
+int xenvif_rx_copy_realloc(struct xenvif_queue *queue, unsigned int size);
void xenvif_carrier_on(struct xenvif *vif);
diff --git a/drivers/net/xen-netback/interface.c
b/drivers/net/xen-netback/interface.c
index 1892bf9327e4..14613b5fcccb 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -516,20 +516,13 @@ struct xenvif *xenvif_alloc(struct device *parent,
domid_t domid,
int xenvif_init_queue(struct xenvif_queue *queue)
{
- unsigned int size = xenvif_copy_batch_size;
int err, i;
- void *addr;
-
- addr = vzalloc(size * sizeof(struct gnttab_copy));
- if (!addr)
- goto err;
- queue->rx_copy.op = addr;
- addr = vzalloc(size * sizeof(RING_IDX));
- if (!addr)
+ err = xenvif_rx_copy_realloc(queue, xenvif_copy_batch_size);
+ if (err) {
+ netdev_err(queue->vif->dev, "Could not alloc rx_copy\n");
goto err;
- queue->rx_copy.idx = addr;
- queue->rx_copy.batch_size = size;
+ }
queue->credit_bytes = queue->remaining_credit = ~0UL;
queue->credit_usec = 0UL;
diff --git a/drivers/net/xen-netback/rx.c b/drivers/net/xen-netback/rx.c
index be3946cdaaf6..f54bfe72188c 100644
--- a/drivers/net/xen-netback/rx.c
+++ b/drivers/net/xen-netback/rx.c
@@ -130,6 +130,51 @@ static void xenvif_rx_queue_drop_expired(struct
xenvif_queue *queue)
}
}
+int xenvif_rx_copy_realloc(struct xenvif_queue *queue, unsigned int size)
+{
+ void *op = NULL, *idx = NULL;
+
+ /* No reallocation if new size doesn't fit ongoing requests */
+ if (!size || queue->rx_copy.num > size)
+ return -EINVAL;
+
+ op = vzalloc(size * sizeof(struct gnttab_copy));
+ if (!op)
+ goto err;
+
+ idx = vzalloc(size * sizeof(RING_IDX));
+ if (!idx)
+ goto err;
+
+ /* Ongoing requests need copying */
+ if (queue->rx_copy.num) {
+ unsigned int tmp;
+
+ tmp = queue->rx_copy.num * sizeof(struct gnttab_copy);
+ memcpy(op, queue->rx_copy.op, tmp);
+
+ tmp = queue->rx_copy.num * sizeof(RING_IDX);
+ memcpy(idx, queue->rx_copy.idx, tmp);
+ }
+
+ if (queue->rx_copy.op || queue->rx_copy.idx) {
+ vfree(queue->rx_copy.op);
+ vfree(queue->rx_copy.idx);
+ }
+
+ queue->rx_copy.op = op;
+ queue->rx_copy.idx = idx;
+ queue->rx_copy.batch_size = size;
+
RE: [PATCH net-next v1] xen-netback: make copy batch size configurable
> -Original Message-
> From: Joao Martins [mailto:joao.m.mart...@oracle.com]
> Sent: 13 November 2017 11:54
> To: Paul Durrant
> Cc: netdev@vger.kernel.org; Wei Liu ; xen-
> de...@lists.xenproject.org
> Subject: Re: [PATCH net-next v1] xen-netback: make copy batch size
> configurable
>
> On 11/13/2017 10:33 AM, Paul Durrant wrote:
> >> -Original Message-
> >> From: Joao Martins [mailto:joao.m.mart...@oracle.com]
> >> Sent: 10 November 2017 19:35
> >> To: netdev@vger.kernel.org
> >> Cc: Joao Martins ; Wei Liu
> >> ; Paul Durrant ; xen-
> >> de...@lists.xenproject.org
> >> Subject: [PATCH net-next v1] xen-netback: make copy batch size
> >> configurable
> >>
> >> Commit eb1723a29b9a ("xen-netback: refactor guest rx") refactored Rx
> >> handling and as a result decreased max grant copy ops from 4352 to 64.
> >> Before this commit it would drain the rx_queue (while there are
> >> enough slots in the ring to put packets) then copy to all pages and write
> >> responses on the ring. With the refactor we do almost the same albeit
> >> the last two steps are done every COPY_BATCH_SIZE (64) copies.
> >>
> >> For big packets, the value of 64 means copying 3 packets best case
> scenario
> >> (17 copies) and worst-case only 1 packet (34 copies, i.e. if all frags
> >> plus head cross the 4k grant boundary) which could be the case when
> >> packets go from local backend process.
> >>
> >> Instead of making it static to 64 grant copies, lets allow the user to
> >> select its value (while keeping the current as default) by introducing
> >> the `copy_batch_size` module parameter. This allows users to select
> >> the higher batches (i.e. for better throughput with big packets) as it
> >> was prior to the above mentioned commit.
> >>
> >> Signed-off-by: Joao Martins
> >> ---
> >> drivers/net/xen-netback/common.h| 6 --
> >> drivers/net/xen-netback/interface.c | 25
> -
> >> drivers/net/xen-netback/netback.c | 5 +
> >> drivers/net/xen-netback/rx.c| 5 -
> >> 4 files changed, 37 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-
> >> netback/common.h
> >> index a46a1e94505d..a5fe36e098a7 100644
> >> --- a/drivers/net/xen-netback/common.h
> >> +++ b/drivers/net/xen-netback/common.h
> >> @@ -129,8 +129,9 @@ struct xenvif_stats {
> >> #define COPY_BATCH_SIZE 64
> >>
> >> struct xenvif_copy_state {
> >> - struct gnttab_copy op[COPY_BATCH_SIZE];
> >> - RING_IDX idx[COPY_BATCH_SIZE];
> >> + struct gnttab_copy *op;
> >> + RING_IDX *idx;
> >> + unsigned int size;
> >
> > Could you name this batch_size, or something like that to make it clear
> what it means?
> >
> Yeap, will change it.
>
> >>unsigned int num;
> >>struct sk_buff_head *completed;
> >> };
> >> @@ -381,6 +382,7 @@ extern unsigned int rx_drain_timeout_msecs;
> >> extern unsigned int rx_stall_timeout_msecs;
> >> extern unsigned int xenvif_max_queues;
> >> extern unsigned int xenvif_hash_cache_size;
> >> +extern unsigned int xenvif_copy_batch_size;
> >>
> >> #ifdef CONFIG_DEBUG_FS
> >> extern struct dentry *xen_netback_dbg_root;
> >> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-
> >> netback/interface.c
> >> index d6dff347f896..a558868a883f 100644
> >> --- a/drivers/net/xen-netback/interface.c
> >> +++ b/drivers/net/xen-netback/interface.c
> >> @@ -516,7 +516,20 @@ struct xenvif *xenvif_alloc(struct device *parent,
> >> domid_t domid,
> >>
> >> int xenvif_init_queue(struct xenvif_queue *queue)
> >> {
> >> + int size = xenvif_copy_batch_size;
> >
> > unsigned int
> >>> int err, i;
> >> + void *addr;
> >> +
> >> + addr = vzalloc(size * sizeof(struct gnttab_copy));
> >
> > Does the memory need to be zeroed?
> >
> It doesn't need to be but given that xenvif_queue is zeroed (which included
> this
> region) thus thought I would leave the same way.
Ok.
>
> >> + if (!addr)
> >> + goto err;
> >> + queue->rx_copy.op = addr;
> >> +
> >> + addr = vzalloc(size * sizeof(RING_IDX));
> >
> > Likewise.
> >
> >> + if (!addr)
> >&
Re: [PATCH net-next v1] xen-netback: make copy batch size configurable
On 11/13/2017 10:33 AM, Paul Durrant wrote:
>> -Original Message-
>> From: Joao Martins [mailto:joao.m.mart...@oracle.com]
>> Sent: 10 November 2017 19:35
>> To: netdev@vger.kernel.org
>> Cc: Joao Martins ; Wei Liu
>> ; Paul Durrant ; xen-
>> de...@lists.xenproject.org
>> Subject: [PATCH net-next v1] xen-netback: make copy batch size
>> configurable
>>
>> Commit eb1723a29b9a ("xen-netback: refactor guest rx") refactored Rx
>> handling and as a result decreased max grant copy ops from 4352 to 64.
>> Before this commit it would drain the rx_queue (while there are
>> enough slots in the ring to put packets) then copy to all pages and write
>> responses on the ring. With the refactor we do almost the same albeit
>> the last two steps are done every COPY_BATCH_SIZE (64) copies.
>>
>> For big packets, the value of 64 means copying 3 packets best case scenario
>> (17 copies) and worst-case only 1 packet (34 copies, i.e. if all frags
>> plus head cross the 4k grant boundary) which could be the case when
>> packets go from local backend process.
>>
>> Instead of making it static to 64 grant copies, lets allow the user to
>> select its value (while keeping the current as default) by introducing
>> the `copy_batch_size` module parameter. This allows users to select
>> the higher batches (i.e. for better throughput with big packets) as it
>> was prior to the above mentioned commit.
>>
>> Signed-off-by: Joao Martins
>> ---
>> drivers/net/xen-netback/common.h| 6 --
>> drivers/net/xen-netback/interface.c | 25 -
>> drivers/net/xen-netback/netback.c | 5 +
>> drivers/net/xen-netback/rx.c| 5 -
>> 4 files changed, 37 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-
>> netback/common.h
>> index a46a1e94505d..a5fe36e098a7 100644
>> --- a/drivers/net/xen-netback/common.h
>> +++ b/drivers/net/xen-netback/common.h
>> @@ -129,8 +129,9 @@ struct xenvif_stats {
>> #define COPY_BATCH_SIZE 64
>>
>> struct xenvif_copy_state {
>> -struct gnttab_copy op[COPY_BATCH_SIZE];
>> -RING_IDX idx[COPY_BATCH_SIZE];
>> +struct gnttab_copy *op;
>> +RING_IDX *idx;
>> +unsigned int size;
>
> Could you name this batch_size, or something like that to make it clear what
> it means?
>
Yeap, will change it.
>> unsigned int num;
>> struct sk_buff_head *completed;
>> };
>> @@ -381,6 +382,7 @@ extern unsigned int rx_drain_timeout_msecs;
>> extern unsigned int rx_stall_timeout_msecs;
>> extern unsigned int xenvif_max_queues;
>> extern unsigned int xenvif_hash_cache_size;
>> +extern unsigned int xenvif_copy_batch_size;
>>
>> #ifdef CONFIG_DEBUG_FS
>> extern struct dentry *xen_netback_dbg_root;
>> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-
>> netback/interface.c
>> index d6dff347f896..a558868a883f 100644
>> --- a/drivers/net/xen-netback/interface.c
>> +++ b/drivers/net/xen-netback/interface.c
>> @@ -516,7 +516,20 @@ struct xenvif *xenvif_alloc(struct device *parent,
>> domid_t domid,
>>
>> int xenvif_init_queue(struct xenvif_queue *queue)
>> {
>> +int size = xenvif_copy_batch_size;
>
> unsigned int
>>> int err, i;
>> +void *addr;
>> +
>> +addr = vzalloc(size * sizeof(struct gnttab_copy));
>
> Does the memory need to be zeroed?
>
It doesn't need to be but given that xenvif_queue is zeroed (which included this
region) thus thought I would leave the same way.
>> +if (!addr)
>> +goto err;
>> +queue->rx_copy.op = addr;
>> +
>> +addr = vzalloc(size * sizeof(RING_IDX));
>
> Likewise.
>
>> +if (!addr)
>> +goto err;
>> +queue->rx_copy.idx = addr;
>> +queue->rx_copy.size = size;
>>
>> queue->credit_bytes = queue->remaining_credit = ~0UL;
>> queue->credit_usec = 0UL;
>> @@ -544,7 +557,7 @@ int xenvif_init_queue(struct xenvif_queue *queue)
>> queue->mmap_pages);
>> if (err) {
>> netdev_err(queue->vif->dev, "Could not reserve
>> mmap_pages\n");
>> -return -ENOMEM;
>> +goto err;
>> }
>>
>> for (i = 0; i < MAX_PENDING_REQS; i++) {
>> @@ -556,6 +569,13 @@ int xenvif_init_queue(struct xenvif_queue *queue)
>> }
>>
>> return 0;
>> +
>> +err:
>> +if (queue->rx_copy.op)
>> +vfree(queue->rx_copy.op);
>
> vfree is safe to be called with NULL.
>
Oh, almost forgot - thanks.
>> +if (queue->rx_copy.idx)
>> +vfree(queue->rx_copy.idx);
>> +return -ENOMEM;
>> }
>>
>> void xenvif_carrier_on(struct xenvif *vif)
>> @@ -788,6 +808,9 @@ void xenvif_disconnect_ctrl(struct xenvif *vif)
>> */
>> void xenvif_deinit_queue(struct xenvif_queue *queue)
>> {
>> +vfree(queue->rx_copy.op);
>> +vfree(queue->rx_copy.idx);
>> +queue->rx_copy.size = 0;
>> gnttab_free_pages(MAX_PENDING_REQS, queue->mmap_pages);
>> }
>>
>> diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-
>> netback/n
RE: [PATCH net-next v1] xen-netback: make copy batch size configurable
> -Original Message-
> From: Joao Martins [mailto:joao.m.mart...@oracle.com]
> Sent: 10 November 2017 19:35
> To: netdev@vger.kernel.org
> Cc: Joao Martins ; Wei Liu
> ; Paul Durrant ; xen-
> de...@lists.xenproject.org
> Subject: [PATCH net-next v1] xen-netback: make copy batch size
> configurable
>
> Commit eb1723a29b9a ("xen-netback: refactor guest rx") refactored Rx
> handling and as a result decreased max grant copy ops from 4352 to 64.
> Before this commit it would drain the rx_queue (while there are
> enough slots in the ring to put packets) then copy to all pages and write
> responses on the ring. With the refactor we do almost the same albeit
> the last two steps are done every COPY_BATCH_SIZE (64) copies.
>
> For big packets, the value of 64 means copying 3 packets best case scenario
> (17 copies) and worst-case only 1 packet (34 copies, i.e. if all frags
> plus head cross the 4k grant boundary) which could be the case when
> packets go from local backend process.
>
> Instead of making it static to 64 grant copies, lets allow the user to
> select its value (while keeping the current as default) by introducing
> the `copy_batch_size` module parameter. This allows users to select
> the higher batches (i.e. for better throughput with big packets) as it
> was prior to the above mentioned commit.
>
> Signed-off-by: Joao Martins
> ---
> drivers/net/xen-netback/common.h| 6 --
> drivers/net/xen-netback/interface.c | 25 -
> drivers/net/xen-netback/netback.c | 5 +
> drivers/net/xen-netback/rx.c| 5 -
> 4 files changed, 37 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-
> netback/common.h
> index a46a1e94505d..a5fe36e098a7 100644
> --- a/drivers/net/xen-netback/common.h
> +++ b/drivers/net/xen-netback/common.h
> @@ -129,8 +129,9 @@ struct xenvif_stats {
> #define COPY_BATCH_SIZE 64
>
> struct xenvif_copy_state {
> - struct gnttab_copy op[COPY_BATCH_SIZE];
> - RING_IDX idx[COPY_BATCH_SIZE];
> + struct gnttab_copy *op;
> + RING_IDX *idx;
> + unsigned int size;
Could you name this batch_size, or something like that to make it clear what it
means?
> unsigned int num;
> struct sk_buff_head *completed;
> };
> @@ -381,6 +382,7 @@ extern unsigned int rx_drain_timeout_msecs;
> extern unsigned int rx_stall_timeout_msecs;
> extern unsigned int xenvif_max_queues;
> extern unsigned int xenvif_hash_cache_size;
> +extern unsigned int xenvif_copy_batch_size;
>
> #ifdef CONFIG_DEBUG_FS
> extern struct dentry *xen_netback_dbg_root;
> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-
> netback/interface.c
> index d6dff347f896..a558868a883f 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -516,7 +516,20 @@ struct xenvif *xenvif_alloc(struct device *parent,
> domid_t domid,
>
> int xenvif_init_queue(struct xenvif_queue *queue)
> {
> + int size = xenvif_copy_batch_size;
unsigned int
> int err, i;
> + void *addr;
> +
> + addr = vzalloc(size * sizeof(struct gnttab_copy));
Does the memory need to be zeroed?
> + if (!addr)
> + goto err;
> + queue->rx_copy.op = addr;
> +
> + addr = vzalloc(size * sizeof(RING_IDX));
Likewise.
> + if (!addr)
> + goto err;
> + queue->rx_copy.idx = addr;
> + queue->rx_copy.size = size;
>
> queue->credit_bytes = queue->remaining_credit = ~0UL;
> queue->credit_usec = 0UL;
> @@ -544,7 +557,7 @@ int xenvif_init_queue(struct xenvif_queue *queue)
>queue->mmap_pages);
> if (err) {
> netdev_err(queue->vif->dev, "Could not reserve
> mmap_pages\n");
> - return -ENOMEM;
> + goto err;
> }
>
> for (i = 0; i < MAX_PENDING_REQS; i++) {
> @@ -556,6 +569,13 @@ int xenvif_init_queue(struct xenvif_queue *queue)
> }
>
> return 0;
> +
> +err:
> + if (queue->rx_copy.op)
> + vfree(queue->rx_copy.op);
vfree is safe to be called with NULL.
> + if (queue->rx_copy.idx)
> + vfree(queue->rx_copy.idx);
> + return -ENOMEM;
> }
>
> void xenvif_carrier_on(struct xenvif *vif)
> @@ -788,6 +808,9 @@ void xenvif_disconnect_ctrl(struct xenvif *vif)
> */
> void xenvif_deinit_queue(struct xenvif_queue *queue)
> {
> + vfree(queue->rx_copy.op);
> + vfree(queue->rx_copy.idx);
> + queue->rx_copy.size = 0;
> gnttab_free_pages(MAX_PENDING_REQS, queue->mmap_pages);
> }
>
> diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-
> netback/netback.c
> index a27daa23c9dc..3a5e1d7ac2f4 100644
> --- a/drivers/net/xen-netback/netback.c
> +++ b/drivers/net/xen-netback/netback.c
> @@ -96,6 +96,11 @@ unsigned int xenvif_hash_cache_size =
> XENVIF_HASH_CACHE_SIZE_DEFAULT;
> module_param_named(hash_cache_size, xenvif_hash_cache_size, uint,
> 0644);
> MODULE_PARM_DESC(
