From: Bobby Eshleman <bobbyeshleman@meta.com>
Refactor sock_devmem_dontneed() in preparation for supporting both
autorelease and manual token release modes.
Split the function into two parts:
- sock_devmem_dontneed(): handles input validation, token allocation,
and copying from userspace
- sock_devmem_dontneed_autorelease(): performs the actual token release
via xarray lookup and page pool put
This separation allows a future commit to add a parallel
sock_devmem_dontneed_manual_release() function that uses a different
token tracking mechanism (per-niov reference counting) without
duplicating the input validation logic.
The refactoring is purely mechanical with no functional change. Only
intended to minimize the noise in subsequent patches.
Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com>
---
net/core/sock.c | 52 ++++++++++++++++++++++++++++++++--------------------
1 file changed, 32 insertions(+), 20 deletions(-)
diff --git a/net/core/sock.c b/net/core/sock.c
index a99132cc0965..e7b378753763 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1082,30 +1082,13 @@ static int sock_reserve_memory(struct sock *sk, int bytes)
#define MAX_DONTNEED_FRAGS 1024
static noinline_for_stack int
-sock_devmem_dontneed(struct sock *sk, sockptr_t optval, unsigned int optlen)
+sock_devmem_dontneed_autorelease(struct sock *sk, struct dmabuf_token *tokens,
+ unsigned int num_tokens)
{
- unsigned int num_tokens, i, j, k, netmem_num = 0;
- struct dmabuf_token *tokens;
+ unsigned int i, j, k, netmem_num = 0;
int ret = 0, num_frags = 0;
netmem_ref netmems[16];
- if (!sk_is_tcp(sk))
- return -EBADF;
-
- if (optlen % sizeof(*tokens) ||
- optlen > sizeof(*tokens) * MAX_DONTNEED_TOKENS)
- return -EINVAL;
-
- num_tokens = optlen / sizeof(*tokens);
- tokens = kvmalloc_array(num_tokens, sizeof(*tokens), GFP_KERNEL);
- if (!tokens)
- return -ENOMEM;
-
- if (copy_from_sockptr(tokens, optval, optlen)) {
- kvfree(tokens);
- return -EFAULT;
- }
-
xa_lock_bh(&sk->sk_user_frags);
for (i = 0; i < num_tokens; i++) {
for (j = 0; j < tokens[i].token_count; j++) {
@@ -1135,6 +1118,35 @@ sock_devmem_dontneed(struct sock *sk, sockptr_t optval, unsigned int optlen)
for (k = 0; k < netmem_num; k++)
WARN_ON_ONCE(!napi_pp_put_page(netmems[k]));
+ return ret;
+}
+
+static noinline_for_stack int
+sock_devmem_dontneed(struct sock *sk, sockptr_t optval, unsigned int optlen)
+{
+ struct dmabuf_token *tokens;
+ unsigned int num_tokens;
+ int ret;
+
+ if (!sk_is_tcp(sk))
+ return -EBADF;
+
+ if (optlen % sizeof(*tokens) ||
+ optlen > sizeof(*tokens) * MAX_DONTNEED_TOKENS)
+ return -EINVAL;
+
+ num_tokens = optlen / sizeof(*tokens);
+ tokens = kvmalloc_array(num_tokens, sizeof(*tokens), GFP_KERNEL);
+ if (!tokens)
+ return -ENOMEM;
+
+ if (copy_from_sockptr(tokens, optval, optlen)) {
+ kvfree(tokens);
+ return -EFAULT;
+ }
+
+ ret = sock_devmem_dontneed_autorelease(sk, tokens, num_tokens);
+
kvfree(tokens);
return ret;
}
--
2.47.3On Thu, Oct 23, 2025 at 2:00 PM Bobby Eshleman <bobbyeshleman@gmail.com> wrote: > > From: Bobby Eshleman <bobbyeshleman@meta.com> > > Refactor sock_devmem_dontneed() in preparation for supporting both > autorelease and manual token release modes. > > Split the function into two parts: > - sock_devmem_dontneed(): handles input validation, token allocation, > and copying from userspace > - sock_devmem_dontneed_autorelease(): performs the actual token release > via xarray lookup and page pool put > > This separation allows a future commit to add a parallel > sock_devmem_dontneed_manual_release() function that uses a different > token tracking mechanism (per-niov reference counting) without > duplicating the input validation logic. > > The refactoring is purely mechanical with no functional change. Only > intended to minimize the noise in subsequent patches. > > Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com> > --- > net/core/sock.c | 52 ++++++++++++++++++++++++++++++++-------------------- > 1 file changed, 32 insertions(+), 20 deletions(-) > > diff --git a/net/core/sock.c b/net/core/sock.c > index a99132cc0965..e7b378753763 100644 > --- a/net/core/sock.c > +++ b/net/core/sock.c > @@ -1082,30 +1082,13 @@ static int sock_reserve_memory(struct sock *sk, int bytes) > #define MAX_DONTNEED_FRAGS 1024 > > static noinline_for_stack int > -sock_devmem_dontneed(struct sock *sk, sockptr_t optval, unsigned int optlen) > +sock_devmem_dontneed_autorelease(struct sock *sk, struct dmabuf_token *tokens, Kind of a misnomer. This helper doesn't seem to autorelease, but really release the provided tokens, I guess. I would have sock_devmem_dontneed_tokens, but naming is hard :D Either way, looks correct code move, Reviewed-by: Mina Almasry <almasrymina@google.com>
On Mon, Oct 27, 2025 at 05:36:35PM -0700, Mina Almasry wrote: > On Thu, Oct 23, 2025 at 2:00 PM Bobby Eshleman <bobbyeshleman@gmail.com> wrote: > > > > From: Bobby Eshleman <bobbyeshleman@meta.com> > > > > Refactor sock_devmem_dontneed() in preparation for supporting both > > autorelease and manual token release modes. > > > > Split the function into two parts: > > - sock_devmem_dontneed(): handles input validation, token allocation, > > and copying from userspace > > - sock_devmem_dontneed_autorelease(): performs the actual token release > > via xarray lookup and page pool put > > > > This separation allows a future commit to add a parallel > > sock_devmem_dontneed_manual_release() function that uses a different > > token tracking mechanism (per-niov reference counting) without > > duplicating the input validation logic. > > > > The refactoring is purely mechanical with no functional change. Only > > intended to minimize the noise in subsequent patches. > > > > Signed-off-by: Bobby Eshleman <bobbyeshleman@meta.com> > > --- > > net/core/sock.c | 52 ++++++++++++++++++++++++++++++++-------------------- > > 1 file changed, 32 insertions(+), 20 deletions(-) > > > > diff --git a/net/core/sock.c b/net/core/sock.c > > index a99132cc0965..e7b378753763 100644 > > --- a/net/core/sock.c > > +++ b/net/core/sock.c > > @@ -1082,30 +1082,13 @@ static int sock_reserve_memory(struct sock *sk, int bytes) > > #define MAX_DONTNEED_FRAGS 1024 > > > > static noinline_for_stack int > > -sock_devmem_dontneed(struct sock *sk, sockptr_t optval, unsigned int optlen) > > +sock_devmem_dontneed_autorelease(struct sock *sk, struct dmabuf_token *tokens, > > Kind of a misnomer. This helper doesn't seem to autorelease, but > really release the provided tokens, I guess. I would have > sock_devmem_dontneed_tokens, but naming is hard :D > > Either way, looks correct code move, > > Reviewed-by: Mina Almasry <almasrymina@google.com> Should we come up with a new name for "autorelease"? I was hoping to find a name that could be consistent from the uAPI down into the token handling code. Maybe "reap" is more clear than "release", since the real difference is whether or not the kernel will reap leaked references on close? Maybe NETDEV_A_DMABUF_REAP_ON_CLOSE on the netlink side, and sock_devmem_dontneed_tokens() and sock_devmem_dontneed_no_reap() here? Best, Bobby
© 2016 - 2026 Red Hat, Inc.