diff options
| author | Alexander Lobakin <aleksander.lobakin@intel.com> | 2023-08-04 21:05:27 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-08-07 23:05:53 +0300 |
| commit | 5b899c33b3b852b9559b724cfee67801324a0886 (patch) | |
| tree | 04f181ec2e4d623f1bea0f1f578a1646619ea18f /net/core | |
| parent | 06d0fbdad612cb8def19065cf1fa14fc34dba9f8 (diff) | |
| download | linux-5b899c33b3b852b9559b724cfee67801324a0886.tar.xz | |
net: skbuff: avoid accessing page_pool if !napi_safe when returning page
Currently, pp->p.napi is always read, but the actual variable it gets
assigned to is read-only when @napi_safe is true. For the !napi_safe
cases, which yet is still a pack, it's an unneeded operation.
Moreover, it can lead to premature or even redundant page_pool
cacheline access. For example, when page_pool_is_last_frag() returns
false (with the recent frag improvements).
Thus, read it only when @napi_safe is true. This also allows moving
@napi inside the condition block itself. Constify it while we are
here, because why not.
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Link: https://lore.kernel.org/r/20230804180529.2483231-5-aleksander.lobakin@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/skbuff.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index acc5844a0de1..85f82a6a08dc 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -882,9 +882,8 @@ static void skb_clone_fraglist(struct sk_buff *skb) #if IS_ENABLED(CONFIG_PAGE_POOL) bool napi_pp_put_page(struct page *page, bool napi_safe) { - struct napi_struct *napi; + bool allow_direct = false; struct page_pool *pp; - bool allow_direct; page = compound_head(page); @@ -904,9 +903,12 @@ bool napi_pp_put_page(struct page *page, bool napi_safe) * in the same context as the consumer would run, so there's * no possible race. */ - napi = READ_ONCE(pp->p.napi); - allow_direct = napi_safe && napi && - READ_ONCE(napi->list_owner) == smp_processor_id(); + if (napi_safe) { + const struct napi_struct *napi = READ_ONCE(pp->p.napi); + + allow_direct = napi && + READ_ONCE(napi->list_owner) == smp_processor_id(); + } /* Driver set this to memory recycling info. Reset it on recycle. * This will *not* work for NIC using a split-page memory model. |