| Message ID | 20221115155744.193789-2-shenwei.wang@nxp.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: fec: add xdp and page pool statistics | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply |
On Tue, Nov 15, 2022 at 09:57:43AM -0600, Shenwei Wang wrote: > The definition of the 'struct page_pool_stats' is required even when > the CONFIG_PAGE_POOL_STATS is not defined. Otherwise, it is required > the drivers to handle the case of CONFIG_PAGE_POOL_STATS undefined. I agree the API is broken, but i think there is a better fix. There should be a stub of page_pool_get_stats() for when CONFIG_PAGE_POOL_STATS is disabled. Nothing actually dereferences struct page_pool_stats when you have this stub. So it might be enough to simply have struct page_pool_stats{ }; Andrew
> -----Original Message----- > From: Andrew Lunn <andrew@lunn.ch> > Sent: Tuesday, November 15, 2022 11:12 AM > To: Shenwei Wang <shenwei.wang@nxp.com> > Cc: David S. Miller <davem@davemloft.net>; Eric Dumazet > <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni > <pabeni@redhat.com>; Jesper Dangaard Brouer <hawk@kernel.org>; Ilias > Apalodimas <ilias.apalodimas@linaro.org>; Alexei Starovoitov > <ast@kernel.org>; Daniel Borkmann <daniel@iogearbox.net>; John Fastabend > <john.fastabend@gmail.com>; netdev@vger.kernel.org; linux- > kernel@vger.kernel.org; imx@lists.linux.dev > Subject: [EXT] Re: [PATCH v4 1/2] net: page_pool: export page_pool_stats > definition > > Caution: EXT Email > > On Tue, Nov 15, 2022 at 09:57:43AM -0600, Shenwei Wang wrote: > > The definition of the 'struct page_pool_stats' is required even when > > the CONFIG_PAGE_POOL_STATS is not defined. Otherwise, it is required > > the drivers to handle the case of CONFIG_PAGE_POOL_STATS undefined. > > I agree the API is broken, but i think there is a better fix. > > There should be a stub of page_pool_get_stats() for when > CONFIG_PAGE_POOL_STATS is disabled. > > Nothing actually dereferences struct page_pool_stats when you have this stub. > So it might be enough to simply have > > struct page_pool_stats{ > }; > As the structure is open when the CONFIG_PAGE_POOL_STATS is enabled, you can not prevent a user to access its members. The empty stub will still have problems in this kind of situations. Regards, Shenwei > Andrew
> > I agree the API is broken, but i think there is a better fix. > > > > There should be a stub of page_pool_get_stats() for when > > CONFIG_PAGE_POOL_STATS is disabled. > > > > Nothing actually dereferences struct page_pool_stats when you have this stub. > > So it might be enough to simply have > > > > struct page_pool_stats{ > > }; > > > > As the structure is open when the CONFIG_PAGE_POOL_STATS is enabled, you can not > prevent a user to access its members. The empty stub will still have problems in this > kind of situations. The users, i.e. the driver, has no need to access its members. The members can change, new ones can be added, and it will not cause a problem, given the way this API is defined. Ideally, page_pool_stats would of been an opaque cookie, but that is not how it was implemented :-( Andrew
> -----Original Message----- > From: Andrew Lunn <andrew@lunn.ch> > Sent: Tuesday, November 15, 2022 11:43 AM > To: Shenwei Wang <shenwei.wang@nxp.com> > Cc: David S. Miller <davem@davemloft.net>; Eric Dumazet > <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni > <pabeni@redhat.com>; Jesper Dangaard Brouer <hawk@kernel.org>; Ilias > Apalodimas <ilias.apalodimas@linaro.org>; Alexei Starovoitov > <ast@kernel.org>; Daniel Borkmann <daniel@iogearbox.net>; John Fastabend > <john.fastabend@gmail.com>; netdev@vger.kernel.org; linux- > kernel@vger.kernel.org; imx@lists.linux.dev > Subject: Re: [EXT] Re: [PATCH v4 1/2] net: page_pool: export page_pool_stats > definition > > Caution: EXT Email > > > > I agree the API is broken, but i think there is a better fix. > > > > > > There should be a stub of page_pool_get_stats() for when > > > CONFIG_PAGE_POOL_STATS is disabled. > > > > > > Nothing actually dereferences struct page_pool_stats when you have this > stub. > > > So it might be enough to simply have > > > > > > struct page_pool_stats{ > > > }; > > > > > > > As the structure is open when the CONFIG_PAGE_POOL_STATS is enabled, > > you can not prevent a user to access its members. The empty stub will > > still have problems in this kind of situations. > > The users, i.e. the driver, has no need to access its members. The members can > change, new ones can be added, and it will not cause a problem, given the way > this API is defined. Ideally, page_pool_stats would of been an opaque cookie, > but that is not how it was implemented :-( > Okay if the assumption is the user would never access its members. Regards, Shenwei > Andrew
diff --git a/include/net/page_pool.h b/include/net/page_pool.h index 813c93499f20..adfd4bb609a7 100644 --- a/include/net/page_pool.h +++ b/include/net/page_pool.h @@ -84,7 +84,6 @@ struct page_pool_params { void *init_arg; }; -#ifdef CONFIG_PAGE_POOL_STATS struct page_pool_alloc_stats { u64 fast; /* fast path allocations */ u64 slow; /* slow-path order 0 allocations */ @@ -117,6 +116,7 @@ struct page_pool_stats { struct page_pool_recycle_stats recycle_stats; }; +#ifdef CONFIG_PAGE_POOL_STATS int page_pool_ethtool_stats_get_count(void); u8 *page_pool_ethtool_stats_get_strings(u8 *data); u64 *page_pool_ethtool_stats_get(u64 *data, void *stats);
The definition of the 'struct page_pool_stats' is required even when the CONFIG_PAGE_POOL_STATS is not defined. Otherwise, it is required the drivers to handle the case of CONFIG_PAGE_POOL_STATS undefined. Signed-off-by: Shenwei Wang <shenwei.wang@nxp.com> --- include/net/page_pool.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)