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[PATCH mptcp-next v3 03/10] mptcp: pm: add established() interface

Geliang Tang posted 10 patches 3 weeks ago
There is a newer version of this series
[PATCH mptcp-next v3 03/10] mptcp: pm: add established() interface
Posted by Geliang Tang 3 weeks ago 
From: Geliang Tang <tanggeliang@kylinos.cn>

This patch adds a .established interface for struct mptcp_pm_ops, and
calls pm->ops->established in from mptcp_pm_worker(). Then get rid of
the corresponding code from __mptcp_pm_kernel_worker().

Since mptcp_pm_addr_send_ack() is a sleepable kfunc, which is invoked
by mptcp_pm_create_subflow_or_signal_addr(), .established() interface
of BPF PM should be invoked by __bpf_prog_enter_sleepable(), which
can't be invoked under a lock. This patch unlocks the pm lock before
invoking this interface in mptcp_pm_worker(), while holding this lock
in mptcp_pm_kernel_established().

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 include/net/mptcp.h   | 3 +++
 net/mptcp/pm.c        | 9 ++++++++-
 net/mptcp/pm_kernel.c | 9 ++++-----
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 9f28ef550e10..d7410f08399e 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -124,6 +124,9 @@ struct mptcp_pm_ops {
 	bool (*get_priority)(struct mptcp_sock *msk,
 			     struct mptcp_addr_info *skc);
 
+	/* optional */
+	void (*established)(struct mptcp_sock *msk);
+
 	char			name[MPTCP_PM_NAME_MAX];
 	struct module		*owner;
 	struct list_head	list;
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 4895318b94cc..a121c08b456e 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -516,7 +516,8 @@ void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk)
 	 * be sure to serve this event only once.
 	 */
 	if (READ_ONCE(pm->work_pending) &&
-	    !(pm->status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)))
+	    !(pm->status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)) &&
+	    pm->ops->established)
 		mptcp_pm_schedule_work(msk, MPTCP_PM_ESTABLISHED);
 
 	if ((pm->status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)) == 0)
@@ -964,6 +965,12 @@ void mptcp_pm_worker(struct mptcp_sock *msk)
 		pm->status &= ~BIT(MPTCP_PM_RM_ADDR_RECEIVED);
 		mptcp_pm_rm_addr_recv(msk);
 	}
+	if (pm->status & BIT(MPTCP_PM_ESTABLISHED)) {
+		pm->status &= ~BIT(MPTCP_PM_ESTABLISHED);
+		spin_unlock_bh(&pm->lock);
+		pm->ops->established(msk);
+		spin_lock_bh(&pm->lock);
+	}
 	__mptcp_pm_kernel_worker(msk);
 
 	spin_unlock_bh(&msk->pm.lock);
diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c
index 7ec81d5195d4..6d30d5958f0e 100644
--- a/net/mptcp/pm_kernel.c
+++ b/net/mptcp/pm_kernel.c
@@ -367,9 +367,11 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
 	mptcp_pm_nl_check_work_pending(msk);
 }
 
-static void mptcp_pm_nl_fully_established(struct mptcp_sock *msk)
+static void mptcp_pm_kernel_established(struct mptcp_sock *msk)
 {
+	spin_lock_bh(&msk->pm.lock);
 	mptcp_pm_create_subflow_or_signal_addr(msk);
+	spin_unlock_bh(&msk->pm.lock);
 }
 
 static void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk)
@@ -1348,10 +1350,6 @@ void __mptcp_pm_kernel_worker(struct mptcp_sock *msk)
 		pm->status &= ~BIT(MPTCP_PM_ADD_ADDR_RECEIVED);
 		mptcp_pm_nl_add_addr_received(msk);
 	}
-	if (pm->status & BIT(MPTCP_PM_ESTABLISHED)) {
-		pm->status &= ~BIT(MPTCP_PM_ESTABLISHED);
-		mptcp_pm_nl_fully_established(msk);
-	}
 	if (pm->status & BIT(MPTCP_PM_SUBFLOW_ESTABLISHED)) {
 		pm->status &= ~BIT(MPTCP_PM_SUBFLOW_ESTABLISHED);
 		mptcp_pm_nl_subflow_established(msk);
@@ -1422,6 +1420,7 @@ static void mptcp_pm_kernel_init(struct mptcp_sock *msk)
 struct mptcp_pm_ops mptcp_pm_kernel = {
 	.get_local_id		= mptcp_pm_kernel_get_local_id,
 	.get_priority		= mptcp_pm_kernel_get_priority,
+	.established		= mptcp_pm_kernel_established,
 	.init			= mptcp_pm_kernel_init,
 	.name			= "kernel",
 	.owner			= THIS_MODULE,
-- 
2.43.0
Re: [PATCH mptcp-next v3 03/10] mptcp: pm: add established() interface
Posted by Matthieu Baerts 3 weeks ago 
Hi Geliang,

On 21/03/2025 02:44, Geliang Tang wrote:
> From: Geliang Tang <tanggeliang@kylinos.cn>
> 
> This patch adds a .established interface for struct mptcp_pm_ops, and
> calls pm->ops->established in from mptcp_pm_worker(). Then get rid of
> the corresponding code from __mptcp_pm_kernel_worker().
> 
> Since mptcp_pm_addr_send_ack() is a sleepable kfunc, which is invoked
> by mptcp_pm_create_subflow_or_signal_addr(), .established() interface
> of BPF PM should be invoked by __bpf_prog_enter_sleepable(), which
> can't be invoked under a lock. This patch unlocks the pm lock before
> invoking this interface in mptcp_pm_worker(), while holding this lock
> in mptcp_pm_kernel_established().
> 
> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
> ---
>  include/net/mptcp.h   | 3 +++
>  net/mptcp/pm.c        | 9 ++++++++-
>  net/mptcp/pm_kernel.c | 9 ++++-----
>  3 files changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/include/net/mptcp.h b/include/net/mptcp.h
> index 9f28ef550e10..d7410f08399e 100644
> --- a/include/net/mptcp.h
> +++ b/include/net/mptcp.h
> @@ -124,6 +124,9 @@ struct mptcp_pm_ops {
>  	bool (*get_priority)(struct mptcp_sock *msk,
>  			     struct mptcp_addr_info *skc);
>  
> +	/* optional */
> +	void (*established)(struct mptcp_sock *msk);
> +
>  	char			name[MPTCP_PM_NAME_MAX];
>  	struct module		*owner;
>  	struct list_head	list;
> diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
> index 4895318b94cc..a121c08b456e 100644
> --- a/net/mptcp/pm.c
> +++ b/net/mptcp/pm.c
> @@ -516,7 +516,8 @@ void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk)
>  	 * be sure to serve this event only once.
>  	 */
>  	if (READ_ONCE(pm->work_pending) &&

For future BPF PM, we will need to deal with this variable. For the
moment, it is not clear, and in-kernel PM specific. I need to think
about that.

> -	    !(pm->status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)))
> +	    !(pm->status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)) &&
> +	    pm->ops->established)
>  		mptcp_pm_schedule_work(msk, MPTCP_PM_ESTABLISHED);
>  
>  	if ((pm->status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)) == 0)
> @@ -964,6 +965,12 @@ void mptcp_pm_worker(struct mptcp_sock *msk)
>  		pm->status &= ~BIT(MPTCP_PM_RM_ADDR_RECEIVED);
>  		mptcp_pm_rm_addr_recv(msk);
>  	}
> +	if (pm->status & BIT(MPTCP_PM_ESTABLISHED)) {
> +		pm->status &= ~BIT(MPTCP_PM_ESTABLISHED);
> +		spin_unlock_bh(&pm->lock);
> +		pm->ops->established(msk);
> +		spin_lock_bh(&pm->lock);

Mmh, do you remember why the lock is held? To protect pm->status I
guess, right?

It looks fine to do the unlock/lock, but that's strange if the goal is
to lock right after.

> +	}
>  	__mptcp_pm_kernel_worker(msk);
>  
>  	spin_unlock_bh(&msk->pm.lock);
> diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c
> index 7ec81d5195d4..6d30d5958f0e 100644
> --- a/net/mptcp/pm_kernel.c
> +++ b/net/mptcp/pm_kernel.c
> @@ -367,9 +367,11 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk)
>  	mptcp_pm_nl_check_work_pending(msk);
>  }
>  
> -static void mptcp_pm_nl_fully_established(struct mptcp_sock *msk)
> +static void mptcp_pm_kernel_established(struct mptcp_sock *msk)
>  {
> +	spin_lock_bh(&msk->pm.lock);
>  	mptcp_pm_create_subflow_or_signal_addr(msk);
> +	spin_unlock_bh(&msk->pm.lock);

Maybe we could move the lock inside
mptcp_pm_create_subflow_or_signal_addr(), only where it is needed?

>  }
>  
>  static void mptcp_pm_nl_subflow_established(struct mptcp_sock *msk)
> @@ -1348,10 +1350,6 @@ void __mptcp_pm_kernel_worker(struct mptcp_sock *msk)
>  		pm->status &= ~BIT(MPTCP_PM_ADD_ADDR_RECEIVED);
>  		mptcp_pm_nl_add_addr_received(msk);
>  	}
> -	if (pm->status & BIT(MPTCP_PM_ESTABLISHED)) {
> -		pm->status &= ~BIT(MPTCP_PM_ESTABLISHED);
> -		mptcp_pm_nl_fully_established(msk);
> -	}
>  	if (pm->status & BIT(MPTCP_PM_SUBFLOW_ESTABLISHED)) {
>  		pm->status &= ~BIT(MPTCP_PM_SUBFLOW_ESTABLISHED);
>  		mptcp_pm_nl_subflow_established(msk);
> @@ -1422,6 +1420,7 @@ static void mptcp_pm_kernel_init(struct mptcp_sock *msk)
>  struct mptcp_pm_ops mptcp_pm_kernel = {
>  	.get_local_id		= mptcp_pm_kernel_get_local_id,
>  	.get_priority		= mptcp_pm_kernel_get_priority,
> +	.established		= mptcp_pm_kernel_established,
>  	.init			= mptcp_pm_kernel_init,
>  	.name			= "kernel",
>  	.owner			= THIS_MODULE,

Cheers,
Matt
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