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netmem: use netmem_desc instead of page to access ->pp in __netmem_get_pp()

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To eliminate the use of the page pool fields in struct page, the page
pool code should use netmem descriptor and APIs instead.

However, __netmem_get_pp() still accesses ->pp via struct page.  So
change it to use struct netmem_desc instead, since ->pp no longer will
be available in struct page.

While at it, add a helper, __netmem_to_nmdesc(), that can be used to
unsafely get pointer to netmem_desc backing the netmem_ref, only when
the netmem_ref is always backed by system memory.

Signed-off-by: Byungchul Park <byungchul@sk.com>
Link: https://patch.msgid.link/20250721021835.63939-3-byungchul@sk.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Byungchul Park
2025-07-21 11:18:25 +09:00
committed by Jakub Kicinski
parent f3d85c9ee5
commit 38a436d4e2
1 changed files with 19 additions and 1 deletions
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20
include/net/netmem.h
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@@ -247,6 +247,24 @@ static inline unsigned long netmem_pfn_trace(netmem_ref netmem)
return page_to_pfn(netmem_to_page(netmem));
}
/**
* __netmem_to_nmdesc - unsafely get pointer to the &netmem_desc backing
* @netmem
* @netmem: netmem reference to convert
*
* Unsafe version that can be used only when @netmem is always backed by
* system memory, performs faster and generates smaller object code (no
* check for the LSB, no WARN). When @netmem points to IOV, provokes
* undefined behaviour.
*
* Return: pointer to the &netmem_desc (garbage if @netmem is not backed
* by system memory).
*/
static inline struct netmem_desc *__netmem_to_nmdesc(netmem_ref netmem)
{
return (__force struct netmem_desc *)netmem;
}
/* __netmem_clear_lsb - convert netmem_ref to struct net_iov * for access to
* common fields.
* @netmem: netmem reference to extract as net_iov.
@@ -280,7 +298,7 @@ static inline struct net_iov *__netmem_clear_lsb(netmem_ref netmem)
*/
static inline struct page_pool *__netmem_get_pp(netmem_ref netmem)
{
return __netmem_to_page(netmem)->pp;
return __netmem_to_nmdesc(netmem)->pp;
}
static inline struct page_pool *netmem_get_pp(netmem_ref netmem)