netdev - Re: [PATCH v3 1/4] net: introduce helper sendpages

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Date: Tue, 11 Jun 2024 09:33:05 +0300
From: Ofir Gal <ofir.gal@...umez.com>
To: Sagi Grimberg <sagi@...mberg.me>, davem@...emloft.net,
 linux-block@...r.kernel.org, linux-nvme@...ts.infradead.org,
 netdev@...r.kernel.org, ceph-devel@...r.kernel.org
Cc: dhowells@...hat.com, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, kbusch@...nel.org, axboe@...nel.dk, hch@....de,
 philipp.reisner@...bit.com, lars.ellenberg@...bit.com,
 christoph.boehmwalder@...bit.com, idryomov@...il.com, xiubli@...hat.com
Subject: Re: [PATCH v3 1/4] net: introduce helper sendpages_ok()



On 10/06/2024 13:05, Sagi Grimberg wrote:
>
>
> On 06/06/2024 19:12, Ofir Gal wrote:
>> Network drivers are using sendpage_ok() to check the first page of an
>> iterator in order to disable MSG_SPLICE_PAGES. The iterator can
>> represent list of contiguous pages.
>>
>> When MSG_SPLICE_PAGES is enabled skb_splice_from_iter() is being used,
>> it requires all pages in the iterator to be sendable. Therefore it needs
>> to check that each page is sendable.
>>
>> The patch introduces a helper sendpages_ok(), it returns true if all the
>> contiguous pages are sendable.
>>
>> Drivers who want to send contiguous pages with MSG_SPLICE_PAGES may use
>> this helper to check whether the page list is OK. If the helper does not
>> return true, the driver should remove MSG_SPLICE_PAGES flag.
>>
>> Reviewed-by: Christoph Hellwig <hch@....de>
>> Signed-off-by: Ofir Gal <ofir.gal@...umez.com>
>> ---
>>   include/linux/net.h | 22 ++++++++++++++++++++++
>>   1 file changed, 22 insertions(+)
>>
>> diff --git a/include/linux/net.h b/include/linux/net.h
>> index 688320b79fcc..421a6b5b9ad1 100644
>> --- a/include/linux/net.h
>> +++ b/include/linux/net.h
>> @@ -322,6 +322,28 @@ static inline bool sendpage_ok(struct page *page)
>>       return !PageSlab(page) && page_count(page) >= 1;
>>   }
>>   +/*
>> + * Check sendpage_ok on contiguous pages.
>> + */
>> +static inline bool sendpages_ok(struct page *page, size_t len, size_t offset)
>> +{
>> +    struct page *p;
>> +    size_t count;
>> +
>> +    p = page + (offset >> PAGE_SHIFT);
>> +
>> +    count = 0;
>
> Assignment can move to the declaration.
Applying to v4.

>
>
>> +    while (count < len) {
>> +        if (!sendpage_ok(p))
>> +            return false;
>> +
>> +        p++;
>> +        count += PAGE_SIZE;
>> +    }
>> +
>> +    return true;
>> +}
>> +
>>   int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,
>>              size_t num, size_t len);
>>   int kernel_sendmsg_locked(struct sock *sk, struct msghdr *msg,
>
> Other than that,
>
> Reviewed-by: Sagi Grimberg <sagi@...mberg.me>
Thanks for the review.