| Message ID | 20250120-tun-v4-8-ee81dda03d7f@daynix.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tun: Unify vnet implementation | expand |
Akihiko Odaki wrote: > hdr_len is repeatedly used so keep it in a local variable. > > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> > --- > drivers/net/tap.c | 17 +++++++---------- > 1 file changed, 7 insertions(+), 10 deletions(-) > > diff --git a/drivers/net/tap.c b/drivers/net/tap.c > index 061c2f27dfc83f5e6d0bea4da0e845cc429b1fd8..7ee2e9ee2a89fd539b087496b92d2f6198266f44 100644 > --- a/drivers/net/tap.c > +++ b/drivers/net/tap.c > @@ -645,6 +645,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, > int err; > struct virtio_net_hdr vnet_hdr = { 0 }; > int vnet_hdr_len = 0; > + int hdr_len = 0; > int copylen = 0; > int depth; > bool zerocopy = false; > @@ -672,6 +673,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, > err = -EINVAL; > if (tap16_to_cpu(q, vnet_hdr.hdr_len) > iov_iter_count(from)) > goto err; > + hdr_len = tap16_to_cpu(q, vnet_hdr.hdr_len); > } > > len = iov_iter_count(from); > @@ -683,11 +685,8 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, > if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) { > struct iov_iter i; > > - copylen = vnet_hdr.hdr_len ? > - tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN; > - if (copylen > good_linear) > - copylen = good_linear; > - else if (copylen < ETH_HLEN) > + copylen = min(hdr_len ? hdr_len : GOODCOPY_LEN, good_linear); > + if (copylen < ETH_HLEN) > copylen = ETH_HLEN; > linear = copylen; > i = *from; > @@ -698,11 +697,9 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, > > if (!zerocopy) { > copylen = len; > - linear = tap16_to_cpu(q, vnet_hdr.hdr_len); > - if (linear > good_linear) > - linear = good_linear; > - else if (linear < ETH_HLEN) > - linear = ETH_HLEN; > + linear = min(hdr_len, good_linear); > + if (copylen < ETH_HLEN) > + copylen = ETH_HLEN; Similar to previous patch, I don't think this patch is significant enough to warrant the code churn.
On 2025/01/20 20:24, Willem de Bruijn wrote: > Akihiko Odaki wrote: >> hdr_len is repeatedly used so keep it in a local variable. >> >> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> >> --- >> drivers/net/tap.c | 17 +++++++---------- >> 1 file changed, 7 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/net/tap.c b/drivers/net/tap.c >> index 061c2f27dfc83f5e6d0bea4da0e845cc429b1fd8..7ee2e9ee2a89fd539b087496b92d2f6198266f44 100644 >> --- a/drivers/net/tap.c >> +++ b/drivers/net/tap.c >> @@ -645,6 +645,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, >> int err; >> struct virtio_net_hdr vnet_hdr = { 0 }; >> int vnet_hdr_len = 0; >> + int hdr_len = 0; >> int copylen = 0; >> int depth; >> bool zerocopy = false; >> @@ -672,6 +673,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, >> err = -EINVAL; >> if (tap16_to_cpu(q, vnet_hdr.hdr_len) > iov_iter_count(from)) >> goto err; >> + hdr_len = tap16_to_cpu(q, vnet_hdr.hdr_len); >> } >> >> len = iov_iter_count(from); >> @@ -683,11 +685,8 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, >> if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) { >> struct iov_iter i; >> >> - copylen = vnet_hdr.hdr_len ? >> - tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN; >> - if (copylen > good_linear) >> - copylen = good_linear; >> - else if (copylen < ETH_HLEN) >> + copylen = min(hdr_len ? hdr_len : GOODCOPY_LEN, good_linear); >> + if (copylen < ETH_HLEN) >> copylen = ETH_HLEN; >> linear = copylen; >> i = *from; >> @@ -698,11 +697,9 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, >> >> if (!zerocopy) { >> copylen = len; >> - linear = tap16_to_cpu(q, vnet_hdr.hdr_len); >> - if (linear > good_linear) >> - linear = good_linear; >> - else if (linear < ETH_HLEN) >> - linear = ETH_HLEN; >> + linear = min(hdr_len, good_linear); >> + if (copylen < ETH_HLEN) >> + copylen = ETH_HLEN; > > Similar to previous patch, I don't think this patch is significant > enough to warrant the code churn. The following patch will require replacing tap16_to_cpu(q, vnet_hdr.hdr_len) with tap16_to_cpu(q->flags, vnet_hdr.hdr_len) It will make some lines a bit too long. Calling tap16_to_cpu() at multiple places is also not good to keep the vnet implementation unified as the function inspects vnet_hdr. This patch is independently too trivial, but I think it is a worthwhile cleanup combined with the following patch.
Akihiko Odaki wrote: > On 2025/01/20 20:24, Willem de Bruijn wrote: > > Akihiko Odaki wrote: > >> hdr_len is repeatedly used so keep it in a local variable. > >> > >> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> > >> --- > >> drivers/net/tap.c | 17 +++++++---------- > >> 1 file changed, 7 insertions(+), 10 deletions(-) > >> > >> diff --git a/drivers/net/tap.c b/drivers/net/tap.c > >> index 061c2f27dfc83f5e6d0bea4da0e845cc429b1fd8..7ee2e9ee2a89fd539b087496b92d2f6198266f44 100644 > >> --- a/drivers/net/tap.c > >> +++ b/drivers/net/tap.c > >> @@ -645,6 +645,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, > >> int err; > >> struct virtio_net_hdr vnet_hdr = { 0 }; > >> int vnet_hdr_len = 0; > >> + int hdr_len = 0; > >> int copylen = 0; > >> int depth; > >> bool zerocopy = false; > >> @@ -672,6 +673,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, > >> err = -EINVAL; > >> if (tap16_to_cpu(q, vnet_hdr.hdr_len) > iov_iter_count(from)) > >> goto err; > >> + hdr_len = tap16_to_cpu(q, vnet_hdr.hdr_len); > >> } > >> > >> len = iov_iter_count(from); > >> @@ -683,11 +685,8 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, > >> if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) { > >> struct iov_iter i; > >> > >> - copylen = vnet_hdr.hdr_len ? > >> - tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN; > >> - if (copylen > good_linear) > >> - copylen = good_linear; > >> - else if (copylen < ETH_HLEN) > >> + copylen = min(hdr_len ? hdr_len : GOODCOPY_LEN, good_linear); > >> + if (copylen < ETH_HLEN) > >> copylen = ETH_HLEN; > >> linear = copylen; > >> i = *from; > >> @@ -698,11 +697,9 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, > >> > >> if (!zerocopy) { > >> copylen = len; > >> - linear = tap16_to_cpu(q, vnet_hdr.hdr_len); > >> - if (linear > good_linear) > >> - linear = good_linear; > >> - else if (linear < ETH_HLEN) > >> - linear = ETH_HLEN; > >> + linear = min(hdr_len, good_linear); > >> + if (copylen < ETH_HLEN) > >> + copylen = ETH_HLEN; > > > > Similar to previous patch, I don't think this patch is significant > > enough to warrant the code churn. > > The following patch will require replacing > tap16_to_cpu(q, vnet_hdr.hdr_len) > with > tap16_to_cpu(q->flags, vnet_hdr.hdr_len) > > It will make some lines a bit too long. Calling tap16_to_cpu() at > multiple places is also not good to keep the vnet implementation unified > as the function inspects vnet_hdr. > > This patch is independently too trivial, but I think it is a worthwhile > cleanup combined with the following patch. Ok. I see what you mean.
diff --git a/drivers/net/tap.c b/drivers/net/tap.c index 061c2f27dfc83f5e6d0bea4da0e845cc429b1fd8..7ee2e9ee2a89fd539b087496b92d2f6198266f44 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -645,6 +645,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, int err; struct virtio_net_hdr vnet_hdr = { 0 }; int vnet_hdr_len = 0; + int hdr_len = 0; int copylen = 0; int depth; bool zerocopy = false; @@ -672,6 +673,7 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, err = -EINVAL; if (tap16_to_cpu(q, vnet_hdr.hdr_len) > iov_iter_count(from)) goto err; + hdr_len = tap16_to_cpu(q, vnet_hdr.hdr_len); } len = iov_iter_count(from); @@ -683,11 +685,8 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) { struct iov_iter i; - copylen = vnet_hdr.hdr_len ? - tap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN; - if (copylen > good_linear) - copylen = good_linear; - else if (copylen < ETH_HLEN) + copylen = min(hdr_len ? hdr_len : GOODCOPY_LEN, good_linear); + if (copylen < ETH_HLEN) copylen = ETH_HLEN; linear = copylen; i = *from; @@ -698,11 +697,9 @@ static ssize_t tap_get_user(struct tap_queue *q, void *msg_control, if (!zerocopy) { copylen = len; - linear = tap16_to_cpu(q, vnet_hdr.hdr_len); - if (linear > good_linear) - linear = good_linear; - else if (linear < ETH_HLEN) - linear = ETH_HLEN; + linear = min(hdr_len, good_linear); + if (copylen < ETH_HLEN) + copylen = ETH_HLEN; } skb = tap_alloc_skb(&q->sk, TAP_RESERVE, copylen,
hdr_len is repeatedly used so keep it in a local variable. Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> --- drivers/net/tap.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-)