[dpdk-dev] virito: fix reuse index in nested loop
Commit Message
This patches fixes problem of reusing index of outmost loop in nested
loops. This bug will lead to failure when starting a multi queue
virtio device: rx queues (except from the first one) cannot be started,
expecially their vq_ring cannot be initialized, so that when invoking
rx func on these queues, segment fault happens.
Fixes: a900472aedef ("virtio: split virtio Rx/Tx queue")
Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
---
drivers/net/virtio/virtio_rxtx.c | 36 ++++++++++++++++++++----------------
1 file changed, 20 insertions(+), 16 deletions(-)
Comments
On Sun, Jun 12, 2016 at 10:05:45AM +0000, Jianfeng Tan wrote:
> This patches fixes problem of reusing index of outmost loop in nested
> loops. This bug will lead to failure when starting a multi queue
> virtio device: rx queues (except from the first one) cannot be started,
> expecially their vq_ring cannot be initialized, so that when invoking
> rx func on these queues, segment fault happens.
>
> Fixes: a900472aedef ("virtio: split virtio Rx/Tx queue")
Good catch!
> Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
> ---
> drivers/net/virtio/virtio_rxtx.c | 36 ++++++++++++++++++++----------------
> 1 file changed, 20 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> index 2e7205b..b96d0cb 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -331,7 +331,7 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
> * - Allocate blank mbufs for the each rx descriptor
> *
> */
> - int i;
> + int i, j;
However, I don't quite like using "i, j, k" stuff. So, how about
renaming "j" to "ring_idx"?
> PMD_INIT_FUNC_TRACE();
>
> @@ -352,15 +352,18 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
> error = ENOSPC;
>
> #ifdef RTE_MACHINE_CPUFLAG_SSSE3
> - if (use_simple_rxtx)
> - for (i = 0; i < vq->vq_nentries; i++) {
> - vq->vq_ring.avail->ring[i] = i;
> - vq->vq_ring.desc[i].flags = VRING_DESC_F_WRITE;
> + if (use_simple_rxtx) {
> + uint16_t k;
We could reuse "ring_idx" here; no need to define yet another iterate var
for that.
--yliu
> -----Original Message-----
> From: Yuanhan Liu [mailto:yuanhan.liu@linux.intel.com]
> Sent: Monday, June 13, 2016 4:58 PM
> To: Tan, Jianfeng
> Cc: dev@dpdk.org; Xie, Huawei
> Subject: Re: [PATCH] virito: fix reuse index in nested loop
>
> On Sun, Jun 12, 2016 at 10:05:45AM +0000, Jianfeng Tan wrote:
> > This patches fixes problem of reusing index of outmost loop in nested
> > loops. This bug will lead to failure when starting a multi queue
> > virtio device: rx queues (except from the first one) cannot be started,
> > expecially their vq_ring cannot be initialized, so that when invoking
> > rx func on these queues, segment fault happens.
> >
> > Fixes: a900472aedef ("virtio: split virtio Rx/Tx queue")
>
> Good catch!
>
> > Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
> > ---
> > drivers/net/virtio/virtio_rxtx.c | 36 ++++++++++++++++++++----------------
> > 1 file changed, 20 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> > index 2e7205b..b96d0cb 100644
> > --- a/drivers/net/virtio/virtio_rxtx.c
> > +++ b/drivers/net/virtio/virtio_rxtx.c
> > @@ -331,7 +331,7 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
> > * - Allocate blank mbufs for the each rx descriptor
> > *
> > */
> > - int i;
> > + int i, j;
>
> However, I don't quite like using "i, j, k" stuff. So, how about
> renaming "j" to "ring_idx"?
>
> > PMD_INIT_FUNC_TRACE();
> >
> > @@ -352,15 +352,18 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
> > error = ENOSPC;
> >
> > #ifdef RTE_MACHINE_CPUFLAG_SSSE3
> > - if (use_simple_rxtx)
> > - for (i = 0; i < vq->vq_nentries; i++) {
> > - vq->vq_ring.avail->ring[i] = i;
> > - vq->vq_ring.desc[i].flags =
> VRING_DESC_F_WRITE;
> > + if (use_simple_rxtx) {
> > + uint16_t k;
>
> We could reuse "ring_idx" here; no need to define yet another iterate var
> for that.
Make sense. Besides, since comparison between unsigned and signed is a violation to static code analyzer, I'll redefine these variables as unsigned.
Such as,
int i -> uint16_t q_idx
int j -> uint16_t r_idx
k -> r_idx
Thanks,
Jianfeng
>
> --yliu
On Mon, Jun 13, 2016 at 09:11:57AM +0000, Tan, Jianfeng wrote:
>
>
> > -----Original Message-----
> > From: Yuanhan Liu [mailto:yuanhan.liu@linux.intel.com]
> > Sent: Monday, June 13, 2016 4:58 PM
> > To: Tan, Jianfeng
> > Cc: dev@dpdk.org; Xie, Huawei
> > Subject: Re: [PATCH] virito: fix reuse index in nested loop
> >
> > On Sun, Jun 12, 2016 at 10:05:45AM +0000, Jianfeng Tan wrote:
> > > This patches fixes problem of reusing index of outmost loop in nested
> > > loops. This bug will lead to failure when starting a multi queue
> > > virtio device: rx queues (except from the first one) cannot be started,
> > > expecially their vq_ring cannot be initialized, so that when invoking
> > > rx func on these queues, segment fault happens.
> > >
> > > Fixes: a900472aedef ("virtio: split virtio Rx/Tx queue")
> >
> > Good catch!
> >
> > > Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
> > > ---
> > > drivers/net/virtio/virtio_rxtx.c | 36 ++++++++++++++++++++----------------
> > > 1 file changed, 20 insertions(+), 16 deletions(-)
> > >
> > > diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> > > index 2e7205b..b96d0cb 100644
> > > --- a/drivers/net/virtio/virtio_rxtx.c
> > > +++ b/drivers/net/virtio/virtio_rxtx.c
> > > @@ -331,7 +331,7 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
> > > * - Allocate blank mbufs for the each rx descriptor
> > > *
> > > */
> > > - int i;
> > > + int i, j;
> >
> > However, I don't quite like using "i, j, k" stuff. So, how about
> > renaming "j" to "ring_idx"?
> >
> > > PMD_INIT_FUNC_TRACE();
> > >
> > > @@ -352,15 +352,18 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
> > > error = ENOSPC;
> > >
> > > #ifdef RTE_MACHINE_CPUFLAG_SSSE3
> > > - if (use_simple_rxtx)
> > > - for (i = 0; i < vq->vq_nentries; i++) {
> > > - vq->vq_ring.avail->ring[i] = i;
> > > - vq->vq_ring.desc[i].flags =
> > VRING_DESC_F_WRITE;
> > > + if (use_simple_rxtx) {
> > > + uint16_t k;
> >
> > We could reuse "ring_idx" here; no need to define yet another iterate var
> > for that.
>
> Make sense. Besides, since comparison between unsigned and signed is a violation to static code analyzer, I'll redefine these variables as unsigned.
> Such as,
> int i -> uint16_t q_idx
> int j -> uint16_t r_idx
> k -> r_idx
It's nothing big deal, but if I were you, I would keep the var name "i"
unchanged (yes, we need define it to uint16_t), and introduce "ring_idx"
but not "r_idx": I will not sacrifice the readability by saving few
typings.
--yliu
@@ -331,7 +331,7 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
* - Allocate blank mbufs for the each rx descriptor
*
*/
- int i;
+ int i, j;
PMD_INIT_FUNC_TRACE();
@@ -352,15 +352,18 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
error = ENOSPC;
#ifdef RTE_MACHINE_CPUFLAG_SSSE3
- if (use_simple_rxtx)
- for (i = 0; i < vq->vq_nentries; i++) {
- vq->vq_ring.avail->ring[i] = i;
- vq->vq_ring.desc[i].flags = VRING_DESC_F_WRITE;
+ if (use_simple_rxtx) {
+ uint16_t k;
+
+ for (k = 0; k < vq->vq_nentries; k++) {
+ vq->vq_ring.avail->ring[k] = k;
+ vq->vq_ring.desc[k].flags = VRING_DESC_F_WRITE;
}
+ }
#endif
memset(&rxvq->fake_mbuf, 0, sizeof(rxvq->fake_mbuf));
- for (i = 0; i < RTE_PMD_VIRTIO_RX_MAX_BURST; i++)
- vq->sw_ring[vq->vq_nentries + i] = &rxvq->fake_mbuf;
+ for (j = 0; j < RTE_PMD_VIRTIO_RX_MAX_BURST; j++)
+ vq->sw_ring[vq->vq_nentries + j] = &rxvq->fake_mbuf;
while (!virtqueue_full(vq)) {
m = rte_mbuf_raw_alloc(rxvq->mpool);
@@ -399,20 +402,21 @@ virtio_dev_rxtx_start(struct rte_eth_dev *dev)
#ifdef RTE_MACHINE_CPUFLAG_SSSE3
if (use_simple_rxtx) {
int mid_idx = vq->vq_nentries >> 1;
- for (i = 0; i < mid_idx; i++) {
- vq->vq_ring.avail->ring[i] = i + mid_idx;
- vq->vq_ring.desc[i + mid_idx].next = i;
- vq->vq_ring.desc[i + mid_idx].addr =
+
+ for (j = 0; j < mid_idx; j++) {
+ vq->vq_ring.avail->ring[j] = j + mid_idx;
+ vq->vq_ring.desc[j + mid_idx].next = j;
+ vq->vq_ring.desc[j + mid_idx].addr =
txvq->virtio_net_hdr_mem +
offsetof(struct virtio_tx_region, tx_hdr);
- vq->vq_ring.desc[i + mid_idx].len =
+ vq->vq_ring.desc[j + mid_idx].len =
vq->hw->vtnet_hdr_size;
- vq->vq_ring.desc[i + mid_idx].flags =
+ vq->vq_ring.desc[j + mid_idx].flags =
VRING_DESC_F_NEXT;
- vq->vq_ring.desc[i].flags = 0;
+ vq->vq_ring.desc[j].flags = 0;
}
- for (i = mid_idx; i < vq->vq_nentries; i++)
- vq->vq_ring.avail->ring[i] = i;
+ for (j = mid_idx; j < vq->vq_nentries; j++)
+ vq->vq_ring.avail->ring[j] = j;
}
#endif
VIRTQUEUE_DUMP(vq);