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Message-ID: <CAHS8izOu=DxeRdD7Gdt-N2qvH_Nnwpcem1KkNgjOLeWzHZ_5JQ@mail.gmail.com>
Date: Thu, 17 Aug 2023 14:56:01 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org, hawk@...nel.org, ilias.apalodimas@...aro.org,
aleksander.lobakin@...el.com, linyunsheng@...wei.com
Subject: Re: [RFC net-next 04/13] net: page_pool: id the page pools
On Wed, Aug 16, 2023 at 4:43 PM Jakub Kicinski <kuba@...nel.org> wrote:
>
> To give ourselves the flexibility of creating netlink commands
> and ability to refer to page pool instances in uAPIs create
> IDs for page pools.
>
Sorry maybe I'm missing something, but it's a bit curious to me that
this ID is needed. An rx queue can only ever have 1 page-pool
associated with it at a time, right? Could you instead add a pointer
to the page_pool into 'struct netdev_rx_queue', and then page-pool can
be referred to by the netdev id & the rx-queue number? Wouldn't that
make the implementation much simpler? I also believe the userspace
refers to the rx-queue by its index number for the ethtool APIs like
adding flow steering rules, so extending that to here maybe makes
sense.
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> ---
> include/net/page_pool/types.h | 4 ++++
> net/core/Makefile | 2 +-
> net/core/page_pool.c | 21 +++++++++++++++-----
> net/core/page_pool_priv.h | 9 +++++++++
> net/core/page_pool_user.c | 36 +++++++++++++++++++++++++++++++++++
> 5 files changed, 66 insertions(+), 6 deletions(-)
> create mode 100644 net/core/page_pool_priv.h
> create mode 100644 net/core/page_pool_user.c
>
> diff --git a/include/net/page_pool/types.h b/include/net/page_pool/types.h
> index 1ac7ce25fbd4..9fadf15dadfa 100644
> --- a/include/net/page_pool/types.h
> +++ b/include/net/page_pool/types.h
> @@ -189,6 +189,10 @@ struct page_pool {
>
> /* Slow/Control-path information follows */
> struct page_pool_params_slow slow;
> + /* User-facing fields, protected by page_pools_lock */
> + struct {
> + u32 id;
> + } user;
> };
>
> struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp);
> diff --git a/net/core/Makefile b/net/core/Makefile
> index 731db2eaa610..4ae3d83f67d5 100644
> --- a/net/core/Makefile
> +++ b/net/core/Makefile
> @@ -18,7 +18,7 @@ obj-y += dev.o dev_addr_lists.o dst.o netevent.o \
> obj-$(CONFIG_NETDEV_ADDR_LIST_TEST) += dev_addr_lists_test.o
>
> obj-y += net-sysfs.o
> -obj-$(CONFIG_PAGE_POOL) += page_pool.o
> +obj-$(CONFIG_PAGE_POOL) += page_pool.o page_pool_user.o
> obj-$(CONFIG_PROC_FS) += net-procfs.o
> obj-$(CONFIG_NET_PKTGEN) += pktgen.o
> obj-$(CONFIG_NETPOLL) += netpoll.o
> diff --git a/net/core/page_pool.c b/net/core/page_pool.c
> index 8e71e116224d..de199c356043 100644
> --- a/net/core/page_pool.c
> +++ b/net/core/page_pool.c
> @@ -23,6 +23,8 @@
>
> #include <trace/events/page_pool.h>
>
> +#include "page_pool_priv.h"
> +
> #define DEFER_TIME (msecs_to_jiffies(1000))
> #define DEFER_WARN_INTERVAL (60 * HZ)
>
> @@ -264,13 +266,21 @@ struct page_pool *page_pool_create(const struct page_pool_params *params)
> return ERR_PTR(-ENOMEM);
>
> err = page_pool_init(pool, params);
> - if (err < 0) {
> - pr_warn("%s() gave up with errno %d\n", __func__, err);
> - kfree(pool);
> - return ERR_PTR(err);
> - }
> + if (err < 0)
> + goto err_free;
> +
> + err = page_pool_list(pool);
> + if (err)
> + goto err_uninit;
>
> return pool;
> +
> +err_uninit:
> + page_pool_uninit(pool);
> +err_free:
> + pr_warn("%s() gave up with errno %d\n", __func__, err);
> + kfree(pool);
> + return ERR_PTR(err);
> }
> EXPORT_SYMBOL(page_pool_create);
>
> @@ -818,6 +828,7 @@ static void page_pool_free(struct page_pool *pool)
> if (pool->disconnect)
> pool->disconnect(pool);
>
> + page_pool_unlist(pool);
> page_pool_uninit(pool);
> kfree(pool);
> }
> diff --git a/net/core/page_pool_priv.h b/net/core/page_pool_priv.h
> new file mode 100644
> index 000000000000..6c4e4aeed02a
> --- /dev/null
> +++ b/net/core/page_pool_priv.h
> @@ -0,0 +1,9 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#ifndef __PAGE_POOL_PRIV_H
> +#define __PAGE_POOL_PRIV_H
> +
> +int page_pool_list(struct page_pool *pool);
> +void page_pool_unlist(struct page_pool *pool);
> +
> +#endif
> diff --git a/net/core/page_pool_user.c b/net/core/page_pool_user.c
> new file mode 100644
> index 000000000000..af4ac38a2de1
> --- /dev/null
> +++ b/net/core/page_pool_user.c
> @@ -0,0 +1,36 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#include <linux/mutex.h>
> +#include <linux/xarray.h>
> +#include <net/page_pool/types.h>
> +
> +#include "page_pool_priv.h"
> +
> +static DEFINE_XARRAY_FLAGS(page_pools, XA_FLAGS_ALLOC1);
> +static DEFINE_MUTEX(page_pools_lock);
> +
> +int page_pool_list(struct page_pool *pool)
> +{
> + static u32 id_alloc_next;
> + int err;
> +
> + mutex_lock(&page_pools_lock);
> + err = xa_alloc_cyclic(&page_pools, &pool->user.id, pool, xa_limit_32b,
> + &id_alloc_next, GFP_KERNEL);
> + if (err < 0)
> + goto err_unlock;
> +
> + mutex_unlock(&page_pools_lock);
> + return 0;
> +
> +err_unlock:
> + mutex_unlock(&page_pools_lock);
> + return err;
> +}
> +
> +void page_pool_unlist(struct page_pool *pool)
> +{
> + mutex_lock(&page_pools_lock);
> + xa_erase(&page_pools, pool->user.id);
> + mutex_unlock(&page_pools_lock);
> +}
> --
> 2.41.0
>
--
Thanks,
Mina
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