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mptcp: cleanup mem accounting.
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After the previous patch, updating sk_forward_memory is cheap and
we can drop a lot of complexity from the MPTCP memory acconting,
removing the custom fwd mem allocations for rmem.

Signed-off-by: Paolo Abeni <[email protected]>
Message-Id: <e45cdca27e17296f261f5ce6d033581f02871c58.1732902181.git.pabeni@redhat.com>
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Paolo Abeni authored and Patchew Applier committed Nov 29, 2024
1 parent 65bfc2d commit 818e1f7
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Showing 3 changed files with 13 additions and 121 deletions.
2 changes: 1 addition & 1 deletion net/mptcp/fastopen.c
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,7 @@ void mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context *subf
mptcp_data_lock(sk);
DEBUG_NET_WARN_ON_ONCE(sock_owned_by_user_nocheck(sk));

mptcp_set_owner_r(skb, sk);
skb_set_owner_r(skb, sk);
__skb_queue_tail(&sk->sk_receive_queue, skb);
mptcp_sk(sk)->bytes_received += skb->len;

Expand Down
128 changes: 11 additions & 117 deletions net/mptcp/protocol.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -118,17 +118,6 @@ static void mptcp_drop(struct sock *sk, struct sk_buff *skb)
__kfree_skb(skb);
}

static void mptcp_rmem_fwd_alloc_add(struct sock *sk, int size)
{
WRITE_ONCE(mptcp_sk(sk)->rmem_fwd_alloc,
mptcp_sk(sk)->rmem_fwd_alloc + size);
}

static void mptcp_rmem_charge(struct sock *sk, int size)
{
mptcp_rmem_fwd_alloc_add(sk, -size);
}

static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to,
struct sk_buff *from)
{
Expand All @@ -149,7 +138,7 @@ static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to,
* negative one
*/
atomic_add(delta, &sk->sk_rmem_alloc);
mptcp_rmem_charge(sk, delta);
sk_mem_charge(sk, delta);
kfree_skb_partial(from, fragstolen);

return true;
Expand All @@ -164,44 +153,6 @@ static bool mptcp_ooo_try_coalesce(struct mptcp_sock *msk, struct sk_buff *to,
return mptcp_try_coalesce((struct sock *)msk, to, from);
}

static void __mptcp_rmem_reclaim(struct sock *sk, int amount)
{
amount >>= PAGE_SHIFT;
mptcp_rmem_charge(sk, amount << PAGE_SHIFT);
__sk_mem_reduce_allocated(sk, amount);
}

static void mptcp_rmem_uncharge(struct sock *sk, int size)
{
struct mptcp_sock *msk = mptcp_sk(sk);
int reclaimable;

mptcp_rmem_fwd_alloc_add(sk, size);
reclaimable = msk->rmem_fwd_alloc - sk_unused_reserved_mem(sk);

/* see sk_mem_uncharge() for the rationale behind the following schema */
if (unlikely(reclaimable >= PAGE_SIZE))
__mptcp_rmem_reclaim(sk, reclaimable);
}

static void mptcp_rfree(struct sk_buff *skb)
{
unsigned int len = skb->truesize;
struct sock *sk = skb->sk;

atomic_sub(len, &sk->sk_rmem_alloc);
mptcp_rmem_uncharge(sk, len);
}

void mptcp_set_owner_r(struct sk_buff *skb, struct sock *sk)
{
skb_orphan(skb);
skb->sk = sk;
skb->destructor = mptcp_rfree;
atomic_add(skb->truesize, &sk->sk_rmem_alloc);
mptcp_rmem_charge(sk, skb->truesize);
}

/* "inspired" by tcp_data_queue_ofo(), main differences:
* - use mptcp seqs
* - don't cope with sacks
Expand Down Expand Up @@ -314,25 +265,7 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *msk, struct sk_buff *skb)

end:
skb_condense(skb);
mptcp_set_owner_r(skb, sk);
}

static bool mptcp_rmem_schedule(struct sock *sk, struct sock *ssk, int size)
{
struct mptcp_sock *msk = mptcp_sk(sk);
int amt, amount;

if (size <= msk->rmem_fwd_alloc)
return true;

size -= msk->rmem_fwd_alloc;
amt = sk_mem_pages(size);
amount = amt << PAGE_SHIFT;
if (!__sk_mem_raise_allocated(sk, size, amt, SK_MEM_RECV))
return false;

mptcp_rmem_fwd_alloc_add(sk, amount);
return true;
skb_set_owner_r(skb, sk);
}

static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
Expand All @@ -350,7 +283,7 @@ static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
skb_orphan(skb);

/* try to fetch required memory from subflow */
if (!mptcp_rmem_schedule(sk, ssk, skb->truesize)) {
if (!sk_rmem_schedule(sk, skb, skb->truesize)) {
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RCVPRUNED);
goto drop;
}
Expand All @@ -374,7 +307,7 @@ static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk,
if (tail && mptcp_try_coalesce(sk, tail, skb))
return true;

mptcp_set_owner_r(skb, sk);
skb_set_owner_r(skb, sk);
__skb_queue_tail(&sk->sk_receive_queue, skb);
return true;
} else if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq)) {
Expand Down Expand Up @@ -1077,17 +1010,10 @@ static void __mptcp_clean_una(struct sock *sk)

static void __mptcp_clean_una_wakeup(struct sock *sk)
{
lockdep_assert_held_once(&sk->sk_lock.slock);

__mptcp_clean_una(sk);
mptcp_write_space(sk);
}

static void mptcp_clean_una_wakeup(struct sock *sk)
{
__mptcp_clean_una_wakeup(sk);
}

static void mptcp_enter_memory_pressure(struct sock *sk)
{
struct mptcp_subflow_context *subflow;
Expand Down Expand Up @@ -1992,9 +1918,10 @@ static int __mptcp_recvmsg_mskq(struct sock *sk,
}

if (!(flags & MSG_PEEK)) {
/* we will bulk release the skb memory later */
/* avoid the indirect call, we know the destructor is sock_wfree */
skb->destructor = NULL;
WRITE_ONCE(msk->rmem_released, msk->rmem_released + skb->truesize);
atomic_sub(skb->truesize, &sk->sk_rmem_alloc);
sk_mem_uncharge(sk, skb->truesize);
__skb_unlink(skb, &sk->sk_receive_queue);
__kfree_skb(skb);
msk->bytes_consumed += count;
Expand Down Expand Up @@ -2107,18 +2034,6 @@ static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied)
msk->rcvq_space.time = mstamp;
}

static void __mptcp_update_rmem(struct sock *sk)
{
struct mptcp_sock *msk = mptcp_sk(sk);

if (!msk->rmem_released)
return;

atomic_sub(msk->rmem_released, &sk->sk_rmem_alloc);
mptcp_rmem_uncharge(sk, msk->rmem_released);
WRITE_ONCE(msk->rmem_released, 0);
}

static bool __mptcp_move_skbs(struct sock *sk)
{
struct mptcp_sock *msk = mptcp_sk(sk);
Expand All @@ -2133,7 +2048,6 @@ static bool __mptcp_move_skbs(struct sock *sk)
break;

slowpath = lock_sock_fast(ssk);
__mptcp_update_rmem(sk);
done = __mptcp_move_skbs_from_subflow(msk, ssk, &moved);

if (unlikely(ssk->sk_err))
Expand All @@ -2143,10 +2057,9 @@ static bool __mptcp_move_skbs(struct sock *sk)

ret = moved > 0;
if (!RB_EMPTY_ROOT(&msk->out_of_order_queue) ||
!skb_queue_empty(&sk->sk_receive_queue)) {
__mptcp_update_rmem(sk);
!skb_queue_empty(&sk->sk_receive_queue))
ret |= __mptcp_ofo_queue(msk);
}

if (ret)
mptcp_check_data_fin((struct sock *)msk);
return ret;
Expand Down Expand Up @@ -2371,17 +2284,13 @@ bool __mptcp_retransmit_pending_data(struct sock *sk)
* some data in the mptcp rtx queue has not really xmitted yet.
* keep it simple and re-inject the whole mptcp level rtx queue
*/
mptcp_data_lock(sk);
__mptcp_clean_una_wakeup(sk);
rtx_head = mptcp_rtx_head(sk);
if (!rtx_head) {
mptcp_data_unlock(sk);
if (!rtx_head)
return false;
}

msk->recovery_snd_nxt = msk->snd_nxt;
msk->recovery = true;
mptcp_data_unlock(sk);

msk->first_pending = rtx_head;
msk->snd_burst = 0;
Expand Down Expand Up @@ -2640,7 +2549,7 @@ static void __mptcp_retrans(struct sock *sk)
int ret, err;
u16 len = 0;

mptcp_clean_una_wakeup(sk);
__mptcp_clean_una_wakeup(sk);

/* first check ssk: need to kick "stale" logic */
err = mptcp_sched_get_retrans(msk);
Expand Down Expand Up @@ -2813,8 +2722,6 @@ static void __mptcp_init_sock(struct sock *sk)
INIT_WORK(&msk->work, mptcp_worker);
msk->out_of_order_queue = RB_ROOT;
msk->first_pending = NULL;
WRITE_ONCE(msk->rmem_fwd_alloc, 0);
WRITE_ONCE(msk->rmem_released, 0);
msk->timer_ival = TCP_RTO_MIN;
msk->scaling_ratio = TCP_DEFAULT_SCALING_RATIO;

Expand Down Expand Up @@ -3040,8 +2947,6 @@ static void __mptcp_destroy_sock(struct sock *sk)

sk->sk_prot->destroy(sk);

WARN_ON_ONCE(READ_ONCE(msk->rmem_fwd_alloc));
WARN_ON_ONCE(msk->rmem_released);
sk_stream_kill_queues(sk);
xfrm_sk_free_policy(sk);

Expand Down Expand Up @@ -3399,8 +3304,6 @@ void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags)
/* move all the rx fwd alloc into the sk_mem_reclaim_final in
* inet_sock_destruct() will dispose it
*/
sk_forward_alloc_add(sk, msk->rmem_fwd_alloc);
WRITE_ONCE(msk->rmem_fwd_alloc, 0);
mptcp_token_destroy(msk);
mptcp_pm_free_anno_list(msk);
mptcp_free_local_addr_list(msk);
Expand Down Expand Up @@ -3493,8 +3396,6 @@ static void mptcp_release_cb(struct sock *sk)
if (__test_and_clear_bit(MPTCP_SYNC_SNDBUF, &msk->cb_flags))
__mptcp_sync_sndbuf(sk);
}

__mptcp_update_rmem(sk);
}

/* MP_JOIN client subflow must wait for 4th ack before sending any data:
Expand Down Expand Up @@ -3665,12 +3566,6 @@ static void mptcp_shutdown(struct sock *sk, int how)
__mptcp_wr_shutdown(sk);
}

static int mptcp_forward_alloc_get(const struct sock *sk)
{
return READ_ONCE(sk->sk_forward_alloc) +
READ_ONCE(mptcp_sk(sk)->rmem_fwd_alloc);
}

static int mptcp_ioctl_outq(const struct mptcp_sock *msk, u64 v)
{
const struct sock *sk = (void *)msk;
Expand Down Expand Up @@ -3828,7 +3723,6 @@ static struct proto mptcp_prot = {
.hash = mptcp_hash,
.unhash = mptcp_unhash,
.get_port = mptcp_get_port,
.forward_alloc_get = mptcp_forward_alloc_get,
.stream_memory_free = mptcp_stream_memory_free,
.sockets_allocated = &mptcp_sockets_allocated,

Expand Down
4 changes: 1 addition & 3 deletions net/mptcp/protocol.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -278,7 +278,6 @@ struct mptcp_sock {
u64 rcv_data_fin_seq;
u64 bytes_retrans;
u64 bytes_consumed;
int rmem_fwd_alloc;
int snd_burst;
int old_wspace;
u64 recovery_snd_nxt; /* in recovery mode accept up to this seq;
Expand All @@ -293,7 +292,6 @@ struct mptcp_sock {
u32 last_ack_recv;
unsigned long timer_ival;
u32 token;
int rmem_released;
unsigned long flags;
unsigned long cb_flags;
bool recovery; /* closing subflow write queue reinjected */
Expand Down Expand Up @@ -384,7 +382,7 @@ static inline void msk_owned_by_me(const struct mptcp_sock *msk)
*/
static inline int __mptcp_rmem(const struct sock *sk)
{
return atomic_read(&sk->sk_rmem_alloc) - READ_ONCE(mptcp_sk(sk)->rmem_released);
return atomic_read(&sk->sk_rmem_alloc);
}

static inline int mptcp_win_from_space(const struct sock *sk, int space)
Expand Down

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