From: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
To: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
<netdev@vger.kernel.org>
Cc: Ira Weiny <ira.weiny@intel.com>,
Ayush Sawal <ayush.sawal@chelsio.com>,
Vinay Kumar Yadav <vinay.yadav@chelsio.com>,
Rohit Maheshwari <rohitm@chelsio.com>
Subject: Re: [PATCH net-next 1/5] ch_ktls: Use kmap_local_page() instead of kmap_atomic()
Date: Fri, 18 Nov 2022 12:38:46 -0800 [thread overview]
Message-ID: <f9d57aea-a0f2-e437-f37a-26c674a60fd5@intel.com> (raw)
In-Reply-To: <4854425.0VBMTVartN@suse>
On 11/18/2022 12:18 PM, Fabio M. De Francesco wrote:
> On venerdì 18 novembre 2022 19:27:56 CET Anirudh Venkataramanan wrote:
>> On 11/18/2022 12:14 AM, Fabio M. De Francesco wrote:
>>> On giovedì 17 novembre 2022 23:25:53 CET Anirudh Venkataramanan wrote:
>>>> kmap_atomic() is being deprecated in favor of kmap_local_page().
>>>> Replace kmap_atomic() and kunmap_atomic() with kmap_local_page()
>>>> and kunmap_local() respectively.
>>>>
>>>> Note that kmap_atomic() disables preemption and page-fault processing,
>>>> but kmap_local_page() doesn't. Converting the former to the latter is
> safe
>>>> only if there isn't an implicit dependency on preemption and page-fault
>>>> handling being disabled, which does appear to be the case here.
>>>>
>>>> Also note that the page being mapped is not allocated by the driver,
>>>> and so the driver doesn't know if the page is in normal memory. This is
> the
>>>> reason kmap_local_page() is used as opposed to page_address().
>>>>
>>>> I don't have hardware, so this change has only been compile tested.
>>>>
>>>> Cc: Ayush Sawal <ayush.sawal@chelsio.com>
>>>> Cc: Vinay Kumar Yadav <vinay.yadav@chelsio.com>
>>>> Cc: Rohit Maheshwari <rohitm@chelsio.com>
>>>> Cc: Ira Weiny <ira.weiny@intel.com>
>>>> Cc: Fabio M. De Francesco <fmdefrancesco@gmail.com>
>>>> Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
>>>> ---
>>>>
>>>> .../ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c | 10 +++++-----
>>>> 1 file changed, 5 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/
> chcr_ktls.c
>>>> b/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c index
>>>> da9973b..d95f230 100644
>>>> --- a/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c
>>>> +++ b/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.c
>>>> @@ -1853,24 +1853,24 @@ static int chcr_short_record_handler(struct
>>>> chcr_ktls_info *tx_info, i++;
>>>>
>>>> }
>>>> f = &record->frags[i];
>>>>
>>>> - vaddr = kmap_atomic(skb_frag_page(f));
>>>> + vaddr = kmap_local_page(skb_frag_page(f));
>>>>
>>>> data = vaddr + skb_frag_off(f) + remaining;
>>>> frag_delta = skb_frag_size(f) - remaining;
>>>>
>>>> if (frag_delta >= prior_data_len) {
>>>>
>>>> memcpy(prior_data, data,
>>>
>>> prior_data_len);
>>>
>>>> - kunmap_atomic(vaddr);
>>>> + kunmap_local(vaddr);
>>>>
>>>> } else {
>>>>
>>>> memcpy(prior_data, data, frag_delta);
>>>>
>>>> - kunmap_atomic(vaddr);
>>>> + kunmap_local(vaddr);
>>>>
>>>> /* get the next page */
>>>> f = &record->frags[i + 1];
>>>>
>>>> - vaddr = kmap_atomic(skb_frag_page(f));
>>>> + vaddr =
>>>
>>> kmap_local_page(skb_frag_page(f));
>>>
>>>> data = vaddr + skb_frag_off(f);
>>>> memcpy(prior_data + frag_delta,
>>>>
>>>> data, (prior_data_len -
>>>
>>> frag_delta));
>>>
>>>> - kunmap_atomic(vaddr);
>>>> + kunmap_local(vaddr);
>>>>
>>>> }
>>>> /* reset tcp_seq as per the prior_data_required
>>>
>>> len */
>>>
>>>> tcp_seq -= prior_data_len;
>>>>
>>>> --
>>>> 2.37.2
>>>
>>> The last conversion could have been done with memcpy_from_page(). However,
>>> it's not that a big deal. Therefore...
>>>
>>> Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
>>
>> Yeah, using memcpy_from_page() is cleaner. I'll update this patch, and
>> probably 4/5 too.
>>
>> Thanks!
>> Ani
>
> Well, I didn't ask you for a second version. This is why you already see my
> "Reviewed-by:" tag. I'm OK with your changes. I just warned you that
> maintainers might ask, so I'd wait and see. However it's up to you.
I understand and appreciate your "Reviewed-by", but that doesn't mean
further improvements aren't possible. I believe using memcpy_from_page()
is better, and plan to do this in v2.
>
> However, if you decide to send this patch with memcpy_from_page(), why you
> are not sure about 4/5? Since you decided to send 1/5 again, what does prevent
> you from updating also 4/5?
I hadn't seen patch 4/5 when I replied to you. Since then I have, and so
I'll be updating 4/5 to use memcpy_from_page() as well.
Ani
next prev parent reply other threads:[~2022-11-18 20:38 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-17 22:25 [PATCH net-next 0/5] Remove uses of kmap_atomic() Anirudh Venkataramanan
2022-11-17 22:25 ` [PATCH net-next 1/5] ch_ktls: Use kmap_local_page() instead " Anirudh Venkataramanan
2022-11-18 8:14 ` Fabio M. De Francesco
2022-11-18 18:27 ` Anirudh Venkataramanan
2022-11-18 20:18 ` Fabio M. De Francesco
2022-11-18 20:38 ` Anirudh Venkataramanan [this message]
2022-11-19 1:22 ` Ira Weiny
2022-11-17 22:25 ` [PATCH net-next 2/5] sfc: " Anirudh Venkataramanan
2022-11-18 8:23 ` Fabio M. De Francesco
2022-11-18 17:47 ` Anirudh Venkataramanan
2022-11-18 19:26 ` Fabio M. De Francesco
2022-11-18 20:34 ` Anirudh Venkataramanan
2022-11-19 1:25 ` Ira Weiny
2022-11-17 22:25 ` [PATCH net-next 3/5] cassini: Remove unnecessary use " Anirudh Venkataramanan
2022-11-18 8:35 ` Fabio M. De Francesco
2022-11-18 17:55 ` Anirudh Venkataramanan
2022-11-18 20:30 ` Fabio M. De Francesco
2022-11-17 22:25 ` [PATCH net-next 4/5] cassini: Use kmap_local_page() instead " Anirudh Venkataramanan
2022-11-18 8:53 ` Fabio M. De Francesco
2022-11-17 22:25 ` [PATCH net-next 5/5] sunvnet: " Anirudh Venkataramanan
2022-11-18 9:11 ` Fabio M. De Francesco
2022-11-18 20:45 ` Fabio M. De Francesco
2022-11-19 0:47 ` Anirudh Venkataramanan
2022-11-22 11:29 ` [PATCH net-next 0/5] Remove uses " Leon Romanovsky
2022-11-22 18:50 ` Jakub Kicinski
2022-11-22 21:06 ` Anirudh Venkataramanan
2022-11-23 7:34 ` Leon Romanovsky
2022-11-23 18:38 ` Anirudh Venkataramanan
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