Re: [PATCH] net: core: datagram: tidy up copy functions a bit
From: Vito Caputo
Date: Sat, 12 Oct 2019 04:55:09 -0700
> + if ((copy = min(start - offset, len)) > 0) {
As Eric said, we try to avoid this very construct these days.
I'm not applying this patch.
Thank you.
Re: [PATCH] net: core: datagram: tidy up copy functions a bit
On 10/13/19 3:41 PM, Vito Caputo wrote: > I read it, thank you for your responses. > > Do you have any guidance to offer someone wanting to contribute with 1-2 > hours available per day? I don't want to cause a nuisance, but would > like to help where I can. My flawed assumption was that small, isolated > hygienic contributions without functionally changing anything would be > appropriate. I suggest you look at the syzkaller huge queue of bugs. You will learn more interesting stuff, and you will help the community in a more quantifiable way. https://syzkaller.appspot.com/upstream
Re: [PATCH] net: core: datagram: tidy up copy functions a bit
On Sun, Oct 13, 2019 at 01:17:18PM -0700, Eric Dumazet wrote:
>
>
> On 10/13/19 1:01 PM, Vito Caputo wrote:
> > On Sun, Oct 13, 2019 at 12:30:41PM -0700, Eric Dumazet wrote:
> >>
> >>
> >> On 10/12/19 4:55 AM, Vito Caputo wrote:
> >>> Eliminate some verbosity by using min() macro and consolidating some
> >>> things, also fix inconsistent zero tests (! vs. == 0).
> >>>
> >>> Signed-off-by: Vito Caputo
> >>> ---
> >>> net/core/datagram.c | 44 ++--
> >>> 1 file changed, 14 insertions(+), 30 deletions(-)
> >>>
> >>> diff --git a/net/core/datagram.c b/net/core/datagram.c
> >>> index 4cc8dc5db2b7..08d403f93952 100644
> >>> --- a/net/core/datagram.c
> >>> +++ b/net/core/datagram.c
> >>> @@ -413,13 +413,11 @@ static int __skb_datagram_iter(const struct sk_buff
> >>> *skb, int offset,
> >>> struct iov_iter *), void *data)
> >>> {
> >>> int start = skb_headlen(skb);
> >>> - int i, copy = start - offset, start_off = offset, n;
> >>> + int i, copy, start_off = offset, n;
> >>> struct sk_buff *frag_iter;
> >>>
> >>> /* Copy header. */
> >>> - if (copy > 0) {
> >>> - if (copy > len)
> >>> - copy = len;
> >>> + if ((copy = min(start - offset, len)) > 0) {
> >>
> >> No, we prefer not having this kind of construct anymore.
> >>
> >> This refactoring looks unnecessary code churn, making our future backports
> >> not
> >> clean cherry-picks.
> >>
> >> Simply making sure this patch does not bring a regression is very time
> >> consuming.
> >
> > Should I not bother submitting patches for such cleanups?
> >
> > I submitted another, more trivial patch, is it also considered unnecessary
> > churn:
> >
> > ---
> >
> > Author: Vito Caputo
> > Date: Sat Oct 12 17:10:41 2019 -0700
> >
> > net: core: skbuff: skb_checksum_setup() drop err
> >
> > Return directly from all switch cases, no point in storing in err.
> >
> > Signed-off-by: Vito Caputo
> >
> > diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> > index f5f904f46893..c59b68a413b5 100644
> > --- a/net/core/skbuff.c
> > +++ b/net/core/skbuff.c
> > @@ -4888,23 +4888,14 @@ static int skb_checksum_setup_ipv6(struct sk_buff
> > *skb, bool recalculate)
> > */
> > int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
> > {
> > - int err;
> > -
> > switch (skb->protocol) {
> > case htons(ETH_P_IP):
> > - err = skb_checksum_setup_ipv4(skb, recalculate);
> > - break;
> > -
> > + return skb_checksum_setup_ipv4(skb, recalculate);
> > case htons(ETH_P_IPV6):
> > - err = skb_checksum_setup_ipv6(skb, recalculate);
> > - break;
> > -
> > + return skb_checksum_setup_ipv6(skb, recalculate);
> > default:
> > - err = -EPROTO;
> > - break;
> > + return -EPROTO;
> > }
> > -
> > - return err;
> > }
> > EXPORT_SYMBOL(skb_checksum_setup);
> >
> > ---
> >
> > Asking to calibrate my thresholds to yours, since I was planning to
> > volunteer
> > some time each evening to reading kernel code and submitting any obvious
> > cleanups.
> >
>
> This is not a cleanup.
>
> You prefer seeing the code written the way you did, but that is really a
> matter of taste.
>
I respectfully disagree with your assertion. When the diff --stat shows
more lines removed than added without harming readability, preferably
improving readability, it's both a cleanup and not a debatable matter of
taste. Having the quantifiable metric of fewer lines of code matters.
> Think about backports of real bug fixes to stable kernels.
>
That's fair, but when the change is an isolated mechanical one in a
single small function, as the one quoted above - is that really of any
significant burden on backports?
> Having these re-writes of code make things less easy for us really.
> So in general we tend to leave the existing code style.
>
> I already replied to the other patch submission, please read
>
> https://marc.info/?l=linux-netdev=157099669227635=2
>
I read it, thank you for your responses.
Do you have any guidance to offer someone wanting to contribute with 1-2
hours available per day? I don't want to cause a nuisance, but would
like to help where I can. My flawed assumption was that small, isolated
hygienic contributions without functionally changing anything would be
appropriate.
Thanks,
Vito Caputo
Re: [PATCH] net: core: datagram: tidy up copy functions a bit
On 10/13/19 1:01 PM, Vito Caputo wrote:
> On Sun, Oct 13, 2019 at 12:30:41PM -0700, Eric Dumazet wrote:
>>
>>
>> On 10/12/19 4:55 AM, Vito Caputo wrote:
>>> Eliminate some verbosity by using min() macro and consolidating some
>>> things, also fix inconsistent zero tests (! vs. == 0).
>>>
>>> Signed-off-by: Vito Caputo
>>> ---
>>> net/core/datagram.c | 44 ++--
>>> 1 file changed, 14 insertions(+), 30 deletions(-)
>>>
>>> diff --git a/net/core/datagram.c b/net/core/datagram.c
>>> index 4cc8dc5db2b7..08d403f93952 100644
>>> --- a/net/core/datagram.c
>>> +++ b/net/core/datagram.c
>>> @@ -413,13 +413,11 @@ static int __skb_datagram_iter(const struct sk_buff
>>> *skb, int offset,
>>> struct iov_iter *), void *data)
>>> {
>>> int start = skb_headlen(skb);
>>> - int i, copy = start - offset, start_off = offset, n;
>>> + int i, copy, start_off = offset, n;
>>> struct sk_buff *frag_iter;
>>>
>>> /* Copy header. */
>>> - if (copy > 0) {
>>> - if (copy > len)
>>> - copy = len;
>>> + if ((copy = min(start - offset, len)) > 0) {
>>
>> No, we prefer not having this kind of construct anymore.
>>
>> This refactoring looks unnecessary code churn, making our future backports
>> not
>> clean cherry-picks.
>>
>> Simply making sure this patch does not bring a regression is very time
>> consuming.
>
> Should I not bother submitting patches for such cleanups?
>
> I submitted another, more trivial patch, is it also considered unnecessary
> churn:
>
> ---
>
> Author: Vito Caputo
> Date: Sat Oct 12 17:10:41 2019 -0700
>
> net: core: skbuff: skb_checksum_setup() drop err
>
> Return directly from all switch cases, no point in storing in err.
>
> Signed-off-by: Vito Caputo
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index f5f904f46893..c59b68a413b5 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -4888,23 +4888,14 @@ static int skb_checksum_setup_ipv6(struct sk_buff
> *skb, bool recalculate)
> */
> int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
> {
> - int err;
> -
> switch (skb->protocol) {
> case htons(ETH_P_IP):
> - err = skb_checksum_setup_ipv4(skb, recalculate);
> - break;
> -
> + return skb_checksum_setup_ipv4(skb, recalculate);
> case htons(ETH_P_IPV6):
> - err = skb_checksum_setup_ipv6(skb, recalculate);
> - break;
> -
> + return skb_checksum_setup_ipv6(skb, recalculate);
> default:
> - err = -EPROTO;
> - break;
> + return -EPROTO;
> }
> -
> - return err;
> }
> EXPORT_SYMBOL(skb_checksum_setup);
>
> ---
>
> Asking to calibrate my thresholds to yours, since I was planning to volunteer
> some time each evening to reading kernel code and submitting any obvious
> cleanups.
>
This is not a cleanup.
You prefer seeing the code written the way you did, but that is really a matter
of taste.
Think about backports of real bug fixes to stable kernels.
Having these re-writes of code make things less easy for us really.
So in general we tend to leave the existing code style.
I already replied to the other patch submission, please read
https://marc.info/?l=linux-netdev=157099669227635=2
Re: [PATCH] net: core: datagram: tidy up copy functions a bit
On Sun, Oct 13, 2019 at 12:30:41PM -0700, Eric Dumazet wrote:
>
>
> On 10/12/19 4:55 AM, Vito Caputo wrote:
> > Eliminate some verbosity by using min() macro and consolidating some
> > things, also fix inconsistent zero tests (! vs. == 0).
> >
> > Signed-off-by: Vito Caputo
> > ---
> > net/core/datagram.c | 44 ++--
> > 1 file changed, 14 insertions(+), 30 deletions(-)
> >
> > diff --git a/net/core/datagram.c b/net/core/datagram.c
> > index 4cc8dc5db2b7..08d403f93952 100644
> > --- a/net/core/datagram.c
> > +++ b/net/core/datagram.c
> > @@ -413,13 +413,11 @@ static int __skb_datagram_iter(const struct sk_buff
> > *skb, int offset,
> > struct iov_iter *), void *data)
> > {
> > int start = skb_headlen(skb);
> > - int i, copy = start - offset, start_off = offset, n;
> > + int i, copy, start_off = offset, n;
> > struct sk_buff *frag_iter;
> >
> > /* Copy header. */
> > - if (copy > 0) {
> > - if (copy > len)
> > - copy = len;
> > + if ((copy = min(start - offset, len)) > 0) {
>
> No, we prefer not having this kind of construct anymore.
>
> This refactoring looks unnecessary code churn, making our future backports not
> clean cherry-picks.
>
> Simply making sure this patch does not bring a regression is very time
> consuming.
Should I not bother submitting patches for such cleanups?
I submitted another, more trivial patch, is it also considered unnecessary
churn:
---
Author: Vito Caputo
Date: Sat Oct 12 17:10:41 2019 -0700
net: core: skbuff: skb_checksum_setup() drop err
Return directly from all switch cases, no point in storing in err.
Signed-off-by: Vito Caputo
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f5f904f46893..c59b68a413b5 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4888,23 +4888,14 @@ static int skb_checksum_setup_ipv6(struct sk_buff *skb,
bool recalculate)
*/
int skb_checksum_setup(struct sk_buff *skb, bool recalculate)
{
- int err;
-
switch (skb->protocol) {
case htons(ETH_P_IP):
- err = skb_checksum_setup_ipv4(skb, recalculate);
- break;
-
+ return skb_checksum_setup_ipv4(skb, recalculate);
case htons(ETH_P_IPV6):
- err = skb_checksum_setup_ipv6(skb, recalculate);
- break;
-
+ return skb_checksum_setup_ipv6(skb, recalculate);
default:
- err = -EPROTO;
- break;
+ return -EPROTO;
}
-
- return err;
}
EXPORT_SYMBOL(skb_checksum_setup);
---
Asking to calibrate my thresholds to yours, since I was planning to volunteer
some time each evening to reading kernel code and submitting any obvious
cleanups.
Thanks,
Vito Caputo
Re: [PATCH] net: core: datagram: tidy up copy functions a bit
On 10/12/19 4:55 AM, Vito Caputo wrote:
> Eliminate some verbosity by using min() macro and consolidating some
> things, also fix inconsistent zero tests (! vs. == 0).
>
> Signed-off-by: Vito Caputo
> ---
> net/core/datagram.c | 44 ++--
> 1 file changed, 14 insertions(+), 30 deletions(-)
>
> diff --git a/net/core/datagram.c b/net/core/datagram.c
> index 4cc8dc5db2b7..08d403f93952 100644
> --- a/net/core/datagram.c
> +++ b/net/core/datagram.c
> @@ -413,13 +413,11 @@ static int __skb_datagram_iter(const struct sk_buff
> *skb, int offset,
> struct iov_iter *), void *data)
> {
> int start = skb_headlen(skb);
> - int i, copy = start - offset, start_off = offset, n;
> + int i, copy, start_off = offset, n;
> struct sk_buff *frag_iter;
>
> /* Copy header. */
> - if (copy > 0) {
> - if (copy > len)
> - copy = len;
> + if ((copy = min(start - offset, len)) > 0) {
No, we prefer not having this kind of construct anymore.
This refactoring looks unnecessary code churn, making our future backports not
clean cherry-picks.
Simply making sure this patch does not bring a regression is very time
consuming.
