netdev - Re: [PATCH iproute2-next 2/2] rdma: Add copy-on-fork to get sys command

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Message-ID: <920dc792-dd72-f125-5546-fff9edb4b9a5@amazon.com>
Date:   Thu, 29 Apr 2021 09:40:16 +0300
From:   Gal Pressman <galpress@...zon.com>
To:     Leon Romanovsky <leon@...nel.org>
CC:     David Ahern <dsahern@...il.com>, <linux-rdma@...r.kernel.org>,
        <netdev@...r.kernel.org>, Yossi Leybovich <sleybo@...zon.com>,
        Alexander Matushevsky <matua@...zon.com>,
        Jason Gunthorpe <jgg@...dia.com>
Subject: Re: [PATCH iproute2-next 2/2] rdma: Add copy-on-fork to get sys
 command

On 28/04/2021 15:00, Leon Romanovsky wrote:
> On Wed, Apr 28, 2021 at 02:42:31PM +0300, Gal Pressman wrote:
>> The new attribute indicates that the kernel copies DMA pages on fork,
>> hence fork support through madvise and MADV_DONTFORK is not needed.
>>
>> If the attribute is not reported (expected on older kernels),
>> copy-on-fork is disabled.
>>
>> Example:
>> $ rdma sys
>> netns shared
>> copy-on-fork on
> 
> I don't think that we need to print them on separate lines.
> $ rdma sys
> netns shared copy-on-fork on

Ack.

>> Signed-off-by: Gal Pressman <galpress@...zon.com>
>> ---
>>  rdma/sys.c | 9 +++++++++
>>  1 file changed, 9 insertions(+)
>>
>> diff --git a/rdma/sys.c b/rdma/sys.c
>> index 8fb565d70598..dd9c6da33e2a 100644
>> --- a/rdma/sys.c
>> +++ b/rdma/sys.c
>> @@ -38,6 +38,15 @@ static int sys_show_parse_cb(const struct nlmsghdr *nlh, void *data)
>>  		print_color_string(PRINT_ANY, COLOR_NONE, "netns", "netns %s\n",
>>  				   mode_str);
>>  	}
>> +
>> +	if (tb[RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK])
>> +		print_color_on_off(PRINT_ANY, COLOR_NONE, "copy-on-fork",
>> +				   "copy-on-fork %s\n",
>> +				   mnl_attr_get_u8(tb[RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK]));
>> +	else
>> +		print_color_on_off(PRINT_ANY, COLOR_NONE, "copy-on-fork",
>> +				   "copy-on-fork %s\n", false);
> 
> Let's simplify it
>         bool cow = false;
> 
>  +	if (tb[RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK])
>  +		cow = mnl_attr_get_u8(tb[RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK]);
>  +
>  +	print_color_on_off(PRINT_ANY, COLOR_NONE, "copy-on-fork", "copy-on-fork %s", cow);

Ack (changed cow -> cof).

Thanks