Merge branch 'fix-late-dma-unmap-crash-for-page-pool'

Toke Høiland-Jørgensen says:

====================
Fix late DMA unmap crash for page pool

This series fixes the late dma_unmap crash for page pool first reported
by Yonglong Liu in [0]. It is an alternative approach to the one
submitted by Yunsheng Lin, most recently in [1]. The first commit just
wraps some tests in a helper function, in preparation of the main change
in patch 2. See the commit message of patch 2 for the details.

[0] https://lore.kernel.org/[email protected]
[1] https://lore.kernel.org/[email protected]

v8: https://lore.kernel.org/[email protected]
v7: https://lore.kernel.org/[email protected]
v6: https://lore.kernel.org/[email protected]
v5: https://lore.kernel.org/[email protected]
v4: https://lore.kernel.org/[email protected]
v3: https://lore.kernel.org/[email protected]
v2: https://lore.kernel.org/[email protected]
v1: https://lore.kernel.org/[email protected]
====================

Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

1 files changed, 32 insertions, 1 deletions

diff --git a/net/core/netmem_priv.h b/net/core/netmem_priv.h
index 7eadb8393e00..cd95394399b4 100644
--- a/net/core/netmem_priv.h
+++ b/net/core/netmem_priv.h
@@ -5,7 +5,7 @@
 
 static inline unsigned long netmem_get_pp_magic(netmem_ref netmem)
 {
-	return __netmem_clear_lsb(netmem)->pp_magic;
+	return __netmem_clear_lsb(netmem)->pp_magic & ~PP_DMA_INDEX_MASK;
 }
 
 static inline void netmem_or_pp_magic(netmem_ref netmem, unsigned long pp_magic)
@@ -15,9 +15,16 @@ static inline void netmem_or_pp_magic(netmem_ref netmem, unsigned long pp_magic)
 
 static inline void netmem_clear_pp_magic(netmem_ref netmem)
 {
+	WARN_ON_ONCE(__netmem_clear_lsb(netmem)->pp_magic & PP_DMA_INDEX_MASK);
+
 	__netmem_clear_lsb(netmem)->pp_magic = 0;
 }
 
+static inline bool netmem_is_pp(netmem_ref netmem)
+{
+	return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) == PP_SIGNATURE;
+}
+
 static inline void netmem_set_pp(netmem_ref netmem, struct page_pool *pool)
 {
 	__netmem_clear_lsb(netmem)->pp = pool;
@@ -28,4 +35,28 @@ static inline void netmem_set_dma_addr(netmem_ref netmem,
 {
 	__netmem_clear_lsb(netmem)->dma_addr = dma_addr;
 }
+
+static inline unsigned long netmem_get_dma_index(netmem_ref netmem)
+{
+	unsigned long magic;
+
+	if (WARN_ON_ONCE(netmem_is_net_iov(netmem)))
+		return 0;
+
+	magic = __netmem_clear_lsb(netmem)->pp_magic;
+
+	return (magic & PP_DMA_INDEX_MASK) >> PP_DMA_INDEX_SHIFT;
+}
+
+static inline void netmem_set_dma_index(netmem_ref netmem,
+					unsigned long id)
+{
+	unsigned long magic;
+
+	if (WARN_ON_ONCE(netmem_is_net_iov(netmem)))
+		return;
+
+	magic = netmem_get_pp_magic(netmem) | (id << PP_DMA_INDEX_SHIFT);
+	__netmem_clear_lsb(netmem)->pp_magic = magic;
+}
 #endif