| Message ID | 20240306235922.282781-2-almasrymina@google.com (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Minor cleanups to skb frag ref/unref | expand |
On Wed, 2024-03-06 at 15:59 -0800, Mina Almasry wrote: > Refactor some of the skb frag ref/unref helpers for improved clarity. > > Implement napi_pp_get_page() to be the mirror counterpart of > napi_pp_put_page(). > > Implement napi_frag_ref() to be the mirror counterpart of > napi_frag_unref(). > > Improve __skb_frag_ref() to become a mirror counterpart of > __skb_frag_unref(). Previously unref could handle pp & non-pp pages, > while the ref could only handle non-pp pages. Now both the ref & unref > helpers can correctly handle both pp & non-pp pages. > > Now that __skb_frag_ref() can handle both pp & non-pp pages, remove > skb_pp_frag_ref(), and use __skb_frag_ref() instead. This lets us > remove pp specific handling from skb_try_coalesce. > > Signed-off-by: Mina Almasry <almasrymina@google.com> > > --- > include/linux/skbuff.h | 24 +++++++++++++++--- > net/core/skbuff.c | 56 ++++++++++++++---------------------------- > 2 files changed, 39 insertions(+), 41 deletions(-) > > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > index d577e0bee18d..51316b0e20bc 100644 > --- a/include/linux/skbuff.h > +++ b/include/linux/skbuff.h > @@ -3477,15 +3477,31 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag) > return netmem_to_page(frag->netmem); > } > > +bool napi_pp_get_page(struct page *page); > + > +static inline void napi_frag_ref(skb_frag_t *frag, bool recycle) > +{ > +#ifdef CONFIG_PAGE_POOL > + struct page *page = skb_frag_page(frag); > + Move assignment out of ifdef. > + if (recycle && napi_pp_get_page(page)) > + return; > +#endif > + get_page(page); > +} > + > /** > * __skb_frag_ref - take an addition reference on a paged fragment. > * @frag: the paged fragment > + * @recycle: skb->pp_recycle param of the parent skb. > * > - * Takes an additional reference on the paged fragment @frag. > + * Takes an additional reference on the paged fragment @frag. Obtains the > + * correct reference count depending on whether skb->pp_recycle is set and > + * whether the frag is a page pool frag. > */ > -static inline void __skb_frag_ref(skb_frag_t *frag) > +static inline void __skb_frag_ref(skb_frag_t *frag, bool recycle) > { > - get_page(skb_frag_page(frag)); > + napi_frag_ref(frag, recycle); > } > > /** > @@ -3497,7 +3513,7 @@ static inline void __skb_frag_ref(skb_frag_t *frag) > */ > static inline void skb_frag_ref(struct sk_buff *skb, int f) > { > - __skb_frag_ref(&skb_shinfo(skb)->frags[f]); > + __skb_frag_ref(&skb_shinfo(skb)->frags[f], skb->pp_recycle); > } > > int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb, > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 1f918e602bc4..6d234faa9d9e 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -1006,6 +1006,21 @@ int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb, > EXPORT_SYMBOL(skb_cow_data_for_xdp); > > #if IS_ENABLED(CONFIG_PAGE_POOL) > +bool napi_pp_get_page(struct page *page) > +{ > + > + struct page *head_page; > + > + head_page = compound_head(page); > + > + if (!is_pp_page(page)) > + return false; > + > + page_pool_ref_page(head_page); > + return true; > +} > +EXPORT_SYMBOL(napi_pp_get_page); > + > bool napi_pp_put_page(struct page *page, bool napi_safe) > { > bool allow_direct = false; > @@ -1058,37 +1073,6 @@ static bool skb_pp_recycle(struct sk_buff *skb, void *data, bool napi_safe) > return napi_pp_put_page(virt_to_page(data), napi_safe); > } > > -/** > - * skb_pp_frag_ref() - Increase fragment references of a page pool aware skb > - * @skb: page pool aware skb > - * > - * Increase the fragment reference count (pp_ref_count) of a skb. This is > - * intended to gain fragment references only for page pool aware skbs, > - * i.e. when skb->pp_recycle is true, and not for fragments in a > - * non-pp-recycling skb. It has a fallback to increase references on normal > - * pages, as page pool aware skbs may also have normal page fragments. > - */ > -static int skb_pp_frag_ref(struct sk_buff *skb) > -{ > - struct skb_shared_info *shinfo; > - struct page *head_page; > - int i; > - > - if (!skb->pp_recycle) > - return -EINVAL; > - > - shinfo = skb_shinfo(skb); > - > - for (i = 0; i < shinfo->nr_frags; i++) { > - head_page = compound_head(skb_frag_page(&shinfo->frags[i])); > - if (likely(is_pp_page(head_page))) > - page_pool_ref_page(head_page); > - else > - page_ref_inc(head_page); > - } > - return 0; > -} > - > static void skb_kfree_head(void *head, unsigned int end_offset) > { > if (end_offset == SKB_SMALL_HEAD_HEADROOM) > @@ -4199,7 +4183,7 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen) > to++; > > } else { > - __skb_frag_ref(fragfrom); > + __skb_frag_ref(fragfrom, skb->pp_recycle); > skb_frag_page_copy(fragto, fragfrom); > skb_frag_off_copy(fragto, fragfrom); > skb_frag_size_set(fragto, todo); > @@ -4849,7 +4833,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, > } > > *nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag; > - __skb_frag_ref(nskb_frag); > + __skb_frag_ref(nskb_frag, nskb->pp_recycle); > size = skb_frag_size(nskb_frag); > > if (pos < offset) { > @@ -5980,10 +5964,8 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, > /* if the skb is not cloned this does nothing > * since we set nr_frags to 0. > */ > - if (skb_pp_frag_ref(from)) { > - for (i = 0; i < from_shinfo->nr_frags; i++) > - __skb_frag_ref(&from_shinfo->frags[i]); > - } > + for (i = 0; i < from_shinfo->nr_frags; i++) > + __skb_frag_ref(&from_shinfo->frags[i], from->pp_recycle); > > to->truesize += delta; > to->len += len;
On 2024/3/7 7:59, Mina Almasry wrote: ... > > int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb, > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 1f918e602bc4..6d234faa9d9e 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -1006,6 +1006,21 @@ int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb, > EXPORT_SYMBOL(skb_cow_data_for_xdp); > > #if IS_ENABLED(CONFIG_PAGE_POOL) > +bool napi_pp_get_page(struct page *page) > +{ > + > + struct page *head_page; > + > + head_page = compound_head(page); > + > + if (!is_pp_page(page)) I would use the head_page for is_pp_page(), I am not sure it matters that much, but I believe it is the precedent. Maybe do the below and remove head_page varible: page = compound_head(page); > + return false; > + > + page_pool_ref_page(head_page); > + return true; > +} > +EXPORT_SYMBOL(napi_pp_get_page); > + ... > - > static void skb_kfree_head(void *head, unsigned int end_offset) > { > if (end_offset == SKB_SMALL_HEAD_HEADROOM) > @@ -4199,7 +4183,7 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen) > to++; > > } else { > - __skb_frag_ref(fragfrom); > + __skb_frag_ref(fragfrom, skb->pp_recycle); > skb_frag_page_copy(fragto, fragfrom); > skb_frag_off_copy(fragto, fragfrom); > skb_frag_size_set(fragto, todo); > @@ -4849,7 +4833,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, > } > > *nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag; > - __skb_frag_ref(nskb_frag); > + __skb_frag_ref(nskb_frag, nskb->pp_recycle); > size = skb_frag_size(nskb_frag); > > if (pos < offset) { > @@ -5980,10 +5964,8 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, > /* if the skb is not cloned this does nothing > * since we set nr_frags to 0. > */ > - if (skb_pp_frag_ref(from)) { I guess it worth mentioning that skb->pp_recycle is only checked once, and skb->pp_recycle is checked for every frag after this patch. > - for (i = 0; i < from_shinfo->nr_frags; i++) > - __skb_frag_ref(&from_shinfo->frags[i]); > - } > + for (i = 0; i < from_shinfo->nr_frags; i++) > + __skb_frag_ref(&from_shinfo->frags[i], from->pp_recycle); > > to->truesize += delta; > to->len += len; >
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index d577e0bee18d..51316b0e20bc 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -3477,15 +3477,31 @@ static inline struct page *skb_frag_page(const skb_frag_t *frag) return netmem_to_page(frag->netmem); } +bool napi_pp_get_page(struct page *page); + +static inline void napi_frag_ref(skb_frag_t *frag, bool recycle) +{ +#ifdef CONFIG_PAGE_POOL + struct page *page = skb_frag_page(frag); + + if (recycle && napi_pp_get_page(page)) + return; +#endif + get_page(page); +} + /** * __skb_frag_ref - take an addition reference on a paged fragment. * @frag: the paged fragment + * @recycle: skb->pp_recycle param of the parent skb. * - * Takes an additional reference on the paged fragment @frag. + * Takes an additional reference on the paged fragment @frag. Obtains the + * correct reference count depending on whether skb->pp_recycle is set and + * whether the frag is a page pool frag. */ -static inline void __skb_frag_ref(skb_frag_t *frag) +static inline void __skb_frag_ref(skb_frag_t *frag, bool recycle) { - get_page(skb_frag_page(frag)); + napi_frag_ref(frag, recycle); } /** @@ -3497,7 +3513,7 @@ static inline void __skb_frag_ref(skb_frag_t *frag) */ static inline void skb_frag_ref(struct sk_buff *skb, int f) { - __skb_frag_ref(&skb_shinfo(skb)->frags[f]); + __skb_frag_ref(&skb_shinfo(skb)->frags[f], skb->pp_recycle); } int skb_pp_cow_data(struct page_pool *pool, struct sk_buff **pskb, diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 1f918e602bc4..6d234faa9d9e 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1006,6 +1006,21 @@ int skb_cow_data_for_xdp(struct page_pool *pool, struct sk_buff **pskb, EXPORT_SYMBOL(skb_cow_data_for_xdp); #if IS_ENABLED(CONFIG_PAGE_POOL) +bool napi_pp_get_page(struct page *page) +{ + + struct page *head_page; + + head_page = compound_head(page); + + if (!is_pp_page(page)) + return false; + + page_pool_ref_page(head_page); + return true; +} +EXPORT_SYMBOL(napi_pp_get_page); + bool napi_pp_put_page(struct page *page, bool napi_safe) { bool allow_direct = false; @@ -1058,37 +1073,6 @@ static bool skb_pp_recycle(struct sk_buff *skb, void *data, bool napi_safe) return napi_pp_put_page(virt_to_page(data), napi_safe); } -/** - * skb_pp_frag_ref() - Increase fragment references of a page pool aware skb - * @skb: page pool aware skb - * - * Increase the fragment reference count (pp_ref_count) of a skb. This is - * intended to gain fragment references only for page pool aware skbs, - * i.e. when skb->pp_recycle is true, and not for fragments in a - * non-pp-recycling skb. It has a fallback to increase references on normal - * pages, as page pool aware skbs may also have normal page fragments. - */ -static int skb_pp_frag_ref(struct sk_buff *skb) -{ - struct skb_shared_info *shinfo; - struct page *head_page; - int i; - - if (!skb->pp_recycle) - return -EINVAL; - - shinfo = skb_shinfo(skb); - - for (i = 0; i < shinfo->nr_frags; i++) { - head_page = compound_head(skb_frag_page(&shinfo->frags[i])); - if (likely(is_pp_page(head_page))) - page_pool_ref_page(head_page); - else - page_ref_inc(head_page); - } - return 0; -} - static void skb_kfree_head(void *head, unsigned int end_offset) { if (end_offset == SKB_SMALL_HEAD_HEADROOM) @@ -4199,7 +4183,7 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen) to++; } else { - __skb_frag_ref(fragfrom); + __skb_frag_ref(fragfrom, skb->pp_recycle); skb_frag_page_copy(fragto, fragfrom); skb_frag_off_copy(fragto, fragfrom); skb_frag_size_set(fragto, todo); @@ -4849,7 +4833,7 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, } *nskb_frag = (i < 0) ? skb_head_frag_to_page_desc(frag_skb) : *frag; - __skb_frag_ref(nskb_frag); + __skb_frag_ref(nskb_frag, nskb->pp_recycle); size = skb_frag_size(nskb_frag); if (pos < offset) { @@ -5980,10 +5964,8 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from, /* if the skb is not cloned this does nothing * since we set nr_frags to 0. */ - if (skb_pp_frag_ref(from)) { - for (i = 0; i < from_shinfo->nr_frags; i++) - __skb_frag_ref(&from_shinfo->frags[i]); - } + for (i = 0; i < from_shinfo->nr_frags; i++) + __skb_frag_ref(&from_shinfo->frags[i], from->pp_recycle); to->truesize += delta; to->len += len;
Refactor some of the skb frag ref/unref helpers for improved clarity. Implement napi_pp_get_page() to be the mirror counterpart of napi_pp_put_page(). Implement napi_frag_ref() to be the mirror counterpart of napi_frag_unref(). Improve __skb_frag_ref() to become a mirror counterpart of __skb_frag_unref(). Previously unref could handle pp & non-pp pages, while the ref could only handle non-pp pages. Now both the ref & unref helpers can correctly handle both pp & non-pp pages. Now that __skb_frag_ref() can handle both pp & non-pp pages, remove skb_pp_frag_ref(), and use __skb_frag_ref() instead. This lets us remove pp specific handling from skb_try_coalesce. Signed-off-by: Mina Almasry <almasrymina@google.com> --- include/linux/skbuff.h | 24 +++++++++++++++--- net/core/skbuff.c | 56 ++++++++++++++---------------------------- 2 files changed, 39 insertions(+), 41 deletions(-)