* [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls
@ 2026-08-17 1:24 Gang Yan
2026-08-17 1:24 ` [PATCH mptcp-next 1/3] mptcp: sched: change scheduler sysctl atomically Gang Yan
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: Gang Yan @ 2026-08-17 1:24 UTC (permalink / raw)
To: mptcp; +Cc: Gang Yan
From: Gang Yan <yangang@kylinos.cn>
Hi,
As decribed in [1], this series is for addressing the KCSAN issues in
sysctls.
Following the tcp_congestion_control() model, patch 1 and 2 now store
pointers to the immutable ops and swap them atomically via xchg().
Patch 3 (from Matthieu) covers the remaining scalar sysctls with READ_ONCE().
[1] https://github.com/multipath-tcp/mptcp_net-next/issues/626
Gang Yan (2):
mptcp: sched: change scheduler sysctl atomically
mptcp: pm: change path_manager sysctl atomically
Matthieu Baerts (NGI0) (1):
mptcp: use READ_ONCE() over sysctls
net/mptcp/ctrl.c | 116 ++++++++++++++++++++++++++++++-------------
net/mptcp/pm.c | 3 +-
net/mptcp/protocol.c | 5 +-
net/mptcp/protocol.h | 6 +--
net/mptcp/sched.c | 2 +-
5 files changed, 91 insertions(+), 41 deletions(-)
--
2.43.0
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH mptcp-next 1/3] mptcp: sched: change scheduler sysctl atomically
2026-08-17 1:24 [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls Gang Yan
@ 2026-08-17 1:24 ` Gang Yan
2026-08-17 1:24 ` [PATCH mptcp-next 2/3] mptcp: pm: change path_manager " Gang Yan
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Gang Yan @ 2026-08-17 1:24 UTC (permalink / raw)
To: mptcp; +Cc: Gang Yan, Tao Cui
From: Gang Yan <yangang@kylinos.cn>
The per-netns scheduler name is stored as an inline char[] buffer and
updated via strscpy() from the sysctl handler. A concurrent reader (e.g.
mptcp_init_sock() resolving the default scheduler) can observe a
half-written name, which is also flagged by KCSAN. READ_ONCE() does not
help here as it cannot read a multi-byte string atomically.
Following the tcp_congestion_control() model, store a pointer to the
immutable struct mptcp_sched_ops instead of the name string:
- mptcp_set_scheduler() now looks the ops up, takes a module reference,
and atomically swaps the pernet pointer with xchg(), releasing the
previous reference;
- mptcp_get_scheduler() copies the ops name out under rcu_read_lock();
- the default reference is taken in mptcp_pernet_set_defaults() and
released in mptcp_net_exit(), mirroring tcp_sk_init()/tcp_sk_exit().
A pointer store is a single atomic word, so readers always observe a
consistent value.
Assisted-by: Claude:GLM5.2
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/626
Co-developed-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Gang Yan <yangang@kylinos.cn>
---
net/mptcp/ctrl.c | 50 +++++++++++++++++++++++++++++++++-----------
net/mptcp/protocol.c | 5 +++--
net/mptcp/protocol.h | 3 ++-
net/mptcp/sched.c | 2 +-
4 files changed, 44 insertions(+), 16 deletions(-)
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 63c5747f0f63..85e9d3e996db 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -39,7 +39,7 @@ struct mptcp_pernet {
u8 allow_join_initial_addr_port;
u8 pm_type;
u8 add_addr_v6_port_drop_ts;
- char scheduler[MPTCP_SCHED_NAME_MAX];
+ struct mptcp_sched_ops __rcu *scheduler;
char path_manager[MPTCP_PM_NAME_MAX];
};
@@ -90,9 +90,14 @@ const char *mptcp_get_path_manager(const struct net *net)
return mptcp_get_pernet(net)->path_manager;
}
-const char *mptcp_get_scheduler(const struct net *net)
+void mptcp_get_scheduler(const struct net *net, char *name)
{
- return mptcp_get_pernet(net)->scheduler;
+ struct mptcp_sched_ops *sched;
+
+ rcu_read_lock();
+ sched = rcu_dereference(mptcp_get_pernet(net)->scheduler);
+ strscpy(name, sched ? sched->name : "default", MPTCP_SCHED_NAME_MAX);
+ rcu_read_unlock();
}
unsigned int mptcp_add_addr_v6_port_drop_ts(const struct net *net)
@@ -112,23 +117,33 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
pernet->allow_join_initial_addr_port = 1;
pernet->stale_loss_cnt = 4;
pernet->pm_type = MPTCP_PM_TYPE_KERNEL;
- strscpy(pernet->scheduler, "default", sizeof(pernet->scheduler));
+
+ if (bpf_try_module_get(&mptcp_sched_default, mptcp_sched_default.owner))
+ RCU_INIT_POINTER(pernet->scheduler, &mptcp_sched_default);
+
strscpy(pernet->path_manager, "kernel", sizeof(pernet->path_manager));
pernet->add_addr_v6_port_drop_ts = 1;
}
#ifdef CONFIG_SYSCTL
-static int mptcp_set_scheduler(char *scheduler, const char *name)
+static int mptcp_set_scheduler(struct mptcp_pernet *pernet, const char *name)
{
- struct mptcp_sched_ops *sched;
+ struct mptcp_sched_ops *sched, *prev;
int ret = 0;
rcu_read_lock();
sched = mptcp_sched_find(name);
- if (sched)
- strscpy(scheduler, name, MPTCP_SCHED_NAME_MAX);
- else
+ if (sched) {
+ if (bpf_try_module_get(sched, sched->owner)) {
+ prev = xchg(&pernet->scheduler, sched);
+ if (prev)
+ bpf_module_put(prev, prev->owner);
+ } else {
+ ret = -EBUSY;
+ }
+ } else {
ret = -ENOENT;
+ }
rcu_read_unlock();
return ret;
@@ -137,7 +152,10 @@ static int mptcp_set_scheduler(char *scheduler, const char *name)
static int proc_scheduler(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
- char (*scheduler)[MPTCP_SCHED_NAME_MAX] = ctl->data;
+ struct mptcp_pernet *pernet = container_of(ctl->data,
+ struct mptcp_pernet,
+ scheduler);
+ struct mptcp_sched_ops *sched;
char val[MPTCP_SCHED_NAME_MAX];
struct ctl_table tbl = {
.data = val,
@@ -145,11 +163,14 @@ static int proc_scheduler(const struct ctl_table *ctl, int write,
};
int ret;
- strscpy(val, *scheduler, MPTCP_SCHED_NAME_MAX);
+ rcu_read_lock();
+ sched = rcu_dereference(pernet->scheduler);
+ strscpy(val, sched ? sched->name : "default", MPTCP_SCHED_NAME_MAX);
+ rcu_read_unlock();
ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
if (write && ret == 0)
- ret = mptcp_set_scheduler(*scheduler, val);
+ ret = mptcp_set_scheduler(pernet, val);
return ret;
}
@@ -573,8 +594,13 @@ static int __net_init mptcp_net_init(struct net *net)
static void __net_exit mptcp_net_exit(struct net *net)
{
struct mptcp_pernet *pernet = mptcp_get_pernet(net);
+ struct mptcp_sched_ops *sched;
mptcp_pernet_del_table(pernet);
+
+ sched = rcu_dereference_protected(pernet->scheduler, true);
+ if (sched)
+ bpf_module_put(sched, sched->owner);
}
static struct pernet_operations mptcp_pernet_ops = {
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index f879b1061f2d..9d84dd803802 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3260,6 +3260,7 @@ static void mptcp_ca_reset(struct sock *sk)
static int mptcp_init_sock(struct sock *sk)
{
struct net *net = sock_net(sk);
+ char sched_name[MPTCP_SCHED_NAME_MAX];
int ret;
__mptcp_init_sock(sk);
@@ -3271,8 +3272,8 @@ static int mptcp_init_sock(struct sock *sk)
return -ENOMEM;
rcu_read_lock();
- ret = mptcp_init_sched(mptcp_sk(sk),
- mptcp_sched_find(mptcp_get_scheduler(net)));
+ mptcp_get_scheduler(net, sched_name);
+ ret = mptcp_init_sched(mptcp_sk(sk), mptcp_sched_find(sched_name));
rcu_read_unlock();
if (ret)
return ret;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 7e168e450fb0..af79b3450ab7 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -803,7 +803,7 @@ unsigned int mptcp_stale_loss_cnt(const struct net *net);
unsigned int mptcp_close_timeout(const struct sock *sk);
int mptcp_get_pm_type(const struct net *net);
const char *mptcp_get_path_manager(const struct net *net);
-const char *mptcp_get_scheduler(const struct net *net);
+void mptcp_get_scheduler(const struct net *net, char *name);
unsigned int mptcp_add_addr_v6_port_drop_ts(const struct net *net);
void mptcp_active_disable(struct sock *sk);
@@ -1155,6 +1155,7 @@ int mptcp_pm_remove_addr(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_
/* the default path manager, used in mptcp_pm_unregister */
extern struct mptcp_pm_ops mptcp_pm_kernel;
+extern struct mptcp_sched_ops mptcp_sched_default;
struct mptcp_pm_ops *mptcp_pm_find(const char *name);
int mptcp_pm_register(struct mptcp_pm_ops *pm_ops);
diff --git a/net/mptcp/sched.c b/net/mptcp/sched.c
index 1e59072d478c..0d13ee46ffdf 100644
--- a/net/mptcp/sched.c
+++ b/net/mptcp/sched.c
@@ -40,7 +40,7 @@ static int mptcp_sched_default_get_retrans(struct mptcp_sock *msk)
return 0;
}
-static struct mptcp_sched_ops mptcp_sched_default = {
+struct mptcp_sched_ops mptcp_sched_default = {
.get_send = mptcp_sched_default_get_send,
.get_retrans = mptcp_sched_default_get_retrans,
.name = "default",
--
2.43.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH mptcp-next 2/3] mptcp: pm: change path_manager sysctl atomically
2026-08-17 1:24 [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls Gang Yan
2026-08-17 1:24 ` [PATCH mptcp-next 1/3] mptcp: sched: change scheduler sysctl atomically Gang Yan
@ 2026-08-17 1:24 ` Gang Yan
2026-08-17 1:24 ` [PATCH mptcp-next 3/3] mptcp: use READ_ONCE() over sysctls Gang Yan
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Gang Yan @ 2026-08-17 1:24 UTC (permalink / raw)
To: mptcp; +Cc: Gang Yan, Tao Cui
From: Gang Yan <yangang@kylinos.cn>
The per-netns path manager name is stored as an inline char[] buffer and
updated via strscpy() from the sysctl handler; a concurrent reader can
observe a half-written name (and KCSAN flags the race), which READ_ONCE()
cannot fix for a multi-byte string.
Following the tcp_congestion_control() model (and the scheduler change in
the previous patch), store a pointer to the immutable struct mptcp_pm_ops
instead of the name string:
- mptcp_set_path_manager() looks the ops up, takes a module reference,
and atomically swaps the pernet pointer with xchg(), releasing the
previous reference;
- mptcp_get_path_manager() copies the ops name out under rcu_read_lock();
- the pm_type field derived from the name is now written
with WRITE_ONCE() to pair with its READ_ONCE() readers;
- the default reference is taken in mptcp_pernet_set_defaults() and
released in mptcp_net_exit().
Assisted-by: Claude:GLM5.2
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/626
Co-developed-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Signed-off-by: Gang Yan <yangang@kylinos.cn>
---
net/mptcp/ctrl.c | 50 +++++++++++++++++++++++++++++++-------------
net/mptcp/pm.c | 3 ++-
net/mptcp/protocol.h | 3 +--
3 files changed, 39 insertions(+), 17 deletions(-)
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 85e9d3e996db..fa28aecfb856 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -40,7 +40,7 @@ struct mptcp_pernet {
u8 pm_type;
u8 add_addr_v6_port_drop_ts;
struct mptcp_sched_ops __rcu *scheduler;
- char path_manager[MPTCP_PM_NAME_MAX];
+ struct mptcp_pm_ops __rcu *path_manager;
};
static struct mptcp_pernet *mptcp_get_pernet(const struct net *net)
@@ -85,9 +85,14 @@ int mptcp_get_pm_type(const struct net *net)
return mptcp_get_pernet(net)->pm_type;
}
-const char *mptcp_get_path_manager(const struct net *net)
+void mptcp_get_path_manager(const struct net *net, char *name)
{
- return mptcp_get_pernet(net)->path_manager;
+ struct mptcp_pm_ops *pm_ops;
+
+ rcu_read_lock();
+ pm_ops = rcu_dereference(mptcp_get_pernet(net)->path_manager);
+ strscpy(name, pm_ops ? pm_ops->name : "kernel", MPTCP_PM_NAME_MAX);
+ rcu_read_unlock();
}
void mptcp_get_scheduler(const struct net *net, char *name)
@@ -121,7 +126,9 @@ static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet)
if (bpf_try_module_get(&mptcp_sched_default, mptcp_sched_default.owner))
RCU_INIT_POINTER(pernet->scheduler, &mptcp_sched_default);
- strscpy(pernet->path_manager, "kernel", sizeof(pernet->path_manager));
+ if (bpf_try_module_get(&mptcp_pm_kernel, mptcp_pm_kernel.owner))
+ RCU_INIT_POINTER(pernet->path_manager, &mptcp_pm_kernel);
+
pernet->add_addr_v6_port_drop_ts = 1;
}
@@ -209,17 +216,24 @@ static int proc_blackhole_detect_timeout(const struct ctl_table *table,
return ret;
}
-static int mptcp_set_path_manager(char *path_manager, const char *name)
+static int mptcp_set_path_manager(struct mptcp_pernet *pernet, const char *name)
{
- struct mptcp_pm_ops *pm_ops;
+ struct mptcp_pm_ops *pm_ops, *prev;
int ret = 0;
rcu_read_lock();
pm_ops = mptcp_pm_find(name);
- if (pm_ops)
- strscpy(path_manager, name, MPTCP_PM_NAME_MAX);
- else
+ if (pm_ops) {
+ if (bpf_try_module_get(pm_ops, pm_ops->owner)) {
+ prev = xchg(&pernet->path_manager, pm_ops);
+ if (prev)
+ bpf_module_put(prev, prev->owner);
+ } else {
+ ret = -EBUSY;
+ }
+ } else {
ret = -ENOENT;
+ }
rcu_read_unlock();
return ret;
@@ -231,7 +245,7 @@ static int proc_path_manager(const struct ctl_table *ctl, int write,
struct mptcp_pernet *pernet = container_of(ctl->data,
struct mptcp_pernet,
path_manager);
- char (*path_manager)[MPTCP_PM_NAME_MAX] = ctl->data;
+ struct mptcp_pm_ops *pm_ops;
char pm_name[MPTCP_PM_NAME_MAX];
const struct ctl_table tbl = {
.data = pm_name,
@@ -239,11 +253,14 @@ static int proc_path_manager(const struct ctl_table *ctl, int write,
};
int ret;
- strscpy(pm_name, *path_manager, MPTCP_PM_NAME_MAX);
+ rcu_read_lock();
+ pm_ops = rcu_dereference(pernet->path_manager);
+ strscpy(pm_name, pm_ops ? pm_ops->name : "kernel", MPTCP_PM_NAME_MAX);
+ rcu_read_unlock();
ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
if (write && ret == 0) {
- ret = mptcp_set_path_manager(*path_manager, pm_name);
+ ret = mptcp_set_path_manager(pernet, pm_name);
if (ret == 0) {
u8 pm_type = __MPTCP_PM_TYPE_NR;
@@ -251,7 +268,7 @@ static int proc_path_manager(const struct ctl_table *ctl, int write,
pm_type = MPTCP_PM_TYPE_KERNEL;
else if (strncmp(pm_name, "userspace", MPTCP_PM_NAME_MAX) == 0)
pm_type = MPTCP_PM_TYPE_USERSPACE;
- pernet->pm_type = pm_type;
+ WRITE_ONCE(pernet->pm_type, pm_type);
}
}
@@ -275,7 +292,7 @@ static int proc_pm_type(const struct ctl_table *ctl, int write,
pm_name = "kernel";
else if (pm_type == MPTCP_PM_TYPE_USERSPACE)
pm_name = "userspace";
- mptcp_set_path_manager(pernet->path_manager, pm_name);
+ mptcp_set_path_manager(pernet, pm_name);
}
return ret;
@@ -595,12 +612,17 @@ static void __net_exit mptcp_net_exit(struct net *net)
{
struct mptcp_pernet *pernet = mptcp_get_pernet(net);
struct mptcp_sched_ops *sched;
+ struct mptcp_pm_ops *pm;
mptcp_pernet_del_table(pernet);
sched = rcu_dereference_protected(pernet->scheduler, true);
if (sched)
bpf_module_put(sched, sched->owner);
+
+ pm = rcu_dereference_protected(pernet->path_manager, true);
+ if (pm)
+ bpf_module_put(pm, pm->owner);
}
static struct pernet_operations mptcp_pernet_ops = {
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index ba7c6f80a183..09f99bcd827c 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -1204,7 +1204,7 @@ void mptcp_pm_destroy(struct mptcp_sock *msk)
void mptcp_pm_data_reset(struct mptcp_sock *msk)
{
const struct net *net = sock_net((struct sock *)msk);
- const char *pm_name = mptcp_get_path_manager(net);
+ char pm_name[MPTCP_PM_NAME_MAX];
u8 pm_type = mptcp_get_pm_type(net);
struct mptcp_pm_data *pm = &msk->pm;
@@ -1213,6 +1213,7 @@ void mptcp_pm_data_reset(struct mptcp_sock *msk)
pm->rm_list_rx.nr = 0;
WRITE_ONCE(pm->pm_type, pm_type);
+ mptcp_get_path_manager(net, pm_name);
rcu_read_lock();
mptcp_pm_ops_init(msk, pm_name);
rcu_read_unlock();
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index af79b3450ab7..99f447f2808f 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -802,7 +802,7 @@ int mptcp_allow_join_id0(const struct net *net);
unsigned int mptcp_stale_loss_cnt(const struct net *net);
unsigned int mptcp_close_timeout(const struct sock *sk);
int mptcp_get_pm_type(const struct net *net);
-const char *mptcp_get_path_manager(const struct net *net);
+void mptcp_get_path_manager(const struct net *net, char *name);
void mptcp_get_scheduler(const struct net *net, char *name);
unsigned int mptcp_add_addr_v6_port_drop_ts(const struct net *net);
@@ -1153,7 +1153,6 @@ int mptcp_pm_announce_addr(struct mptcp_sock *msk,
bool echo);
int mptcp_pm_remove_addr(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_list);
-/* the default path manager, used in mptcp_pm_unregister */
extern struct mptcp_pm_ops mptcp_pm_kernel;
extern struct mptcp_sched_ops mptcp_sched_default;
--
2.43.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH mptcp-next 3/3] mptcp: use READ_ONCE() over sysctls
2026-08-17 1:24 [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls Gang Yan
2026-08-17 1:24 ` [PATCH mptcp-next 1/3] mptcp: sched: change scheduler sysctl atomically Gang Yan
2026-08-17 1:24 ` [PATCH mptcp-next 2/3] mptcp: pm: change path_manager " Gang Yan
@ 2026-08-17 1:24 ` Gang Yan
2026-08-17 2:31 ` [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls MPTCP CI
2026-08-17 17:43 ` Matthieu Baerts
4 siblings, 0 replies; 6+ messages in thread
From: Gang Yan @ 2026-08-17 1:24 UTC (permalink / raw)
To: mptcp; +Cc: Matthieu Baerts (NGI0), Eric Dumazet
From: "Matthieu Baerts (NGI0)" <matttbe@kernel.org>
To avoid KCSAN issues.
This patch is in theory for -net, and will need to be split in multiple
patches, with different Fixes tags. But I prefer to wait for Eric's
patches, as I noticed he already started to modify mptcp_is_enabled:
https://lore.kernel.org/CANn89iLdwhhwLyO6zRjWMEY3t9g60ZE8ZhOVx33ucg_uRETbmQ@mail.gmail.com
Still, keeping this patch in this series, not to forget about it.
Reported-by: Eric Dumazet <edumazet@google.com>
Closes: https://lore.kernel.org/CANn89iL=os-60kDKqMDdyiXuPF5CG=eejS0vmthwpDGXz_Bp8A@mail.gmail.com
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
net/mptcp/ctrl.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index fa28aecfb856..309bbb2a4eb0 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -50,39 +50,39 @@ static struct mptcp_pernet *mptcp_get_pernet(const struct net *net)
int mptcp_is_enabled(const struct net *net)
{
- return mptcp_get_pernet(net)->mptcp_enabled;
+ return READ_ONCE(mptcp_get_pernet(net)->mptcp_enabled);
}
unsigned int mptcp_get_add_addr_timeout(const struct net *net)
{
- return mptcp_get_pernet(net)->add_addr_timeout;
+ return READ_ONCE(mptcp_get_pernet(net)->add_addr_timeout);
}
int mptcp_is_checksum_enabled(const struct net *net)
{
- return mptcp_get_pernet(net)->checksum_enabled;
+ return READ_ONCE(mptcp_get_pernet(net)->checksum_enabled);
}
int mptcp_allow_join_id0(const struct net *net)
{
- return mptcp_get_pernet(net)->allow_join_initial_addr_port;
+ return READ_ONCE(mptcp_get_pernet(net)->allow_join_initial_addr_port);
}
unsigned int mptcp_stale_loss_cnt(const struct net *net)
{
- return mptcp_get_pernet(net)->stale_loss_cnt;
+ return READ_ONCE(mptcp_get_pernet(net)->stale_loss_cnt);
}
unsigned int mptcp_close_timeout(const struct sock *sk)
{
if (sock_flag(sk, SOCK_DEAD))
return TCP_TIMEWAIT_LEN;
- return mptcp_get_pernet(sock_net(sk))->close_timeout;
+ return READ_ONCE(mptcp_get_pernet(sock_net(sk))->close_timeout);
}
int mptcp_get_pm_type(const struct net *net)
{
- return mptcp_get_pernet(net)->pm_type;
+ return READ_ONCE(mptcp_get_pernet(net)->pm_type);
}
void mptcp_get_path_manager(const struct net *net, char *name)
@@ -589,7 +589,7 @@ void mptcp_active_detect_blackhole(struct sock *ssk, bool expired)
net = sock_net(ssk);
timeouts = inet_csk(ssk)->icsk_retransmits;
- to_max = mptcp_get_pernet(net)->syn_retrans_before_tcp_fallback;
+ to_max = READ_ONCE(mptcp_get_pernet(net)->syn_retrans_before_tcp_fallback);
if (timeouts == to_max || (timeouts < to_max && expired)) {
subflow->mpc_drop = 1;
--
2.43.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls
2026-08-17 1:24 [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls Gang Yan
` (2 preceding siblings ...)
2026-08-17 1:24 ` [PATCH mptcp-next 3/3] mptcp: use READ_ONCE() over sysctls Gang Yan
@ 2026-08-17 2:31 ` MPTCP CI
2026-08-17 17:43 ` Matthieu Baerts
4 siblings, 0 replies; 6+ messages in thread
From: MPTCP CI @ 2026-08-17 2:31 UTC (permalink / raw)
To: Matthieu Baerts; +Cc: mptcp
Hi Matthieu,
Thank you for your modifications, that's great!
Our CI did some validations and here is its report:
- KVM Validation: normal (except selftest_mptcp_join): Success! ✅
- KVM Validation: normal (only selftest_mptcp_join): Success! ✅
- KVM Validation: debug (except selftest_mptcp_join): Success! ✅
- KVM Validation: debug (only selftest_mptcp_join): Success! ✅
- KVM Validation: btf-normal (only bpftest_all): Success! ✅
- KVM Validation: btf-debug (only bpftest_all): Success! ✅
- Task: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/31986048689
Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/fa35ee6d384f
Patchwork: https://patchwork.kernel.org/project/mptcp/list/?series=1146872
If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:
$ cd [kernel source code]
$ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
--pull always mptcp/mptcp-upstream-virtme-docker:latest \
auto-normal
For more details:
https://github.com/multipath-tcp/mptcp-upstream-virtme-docker
Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)
Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (NGI0 Core)
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls
2026-08-17 1:24 [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls Gang Yan
` (3 preceding siblings ...)
2026-08-17 2:31 ` [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls MPTCP CI
@ 2026-08-17 17:43 ` Matthieu Baerts
4 siblings, 0 replies; 6+ messages in thread
From: Matthieu Baerts @ 2026-08-17 17:43 UTC (permalink / raw)
To: Gang Yan, mptcp; +Cc: Gang Yan
Hi Gang Yan,
On 17/08/2026 03:24, Gang Yan wrote:
> From: Gang Yan <yangang@kylinos.cn>
>
> Hi,
>
> As decribed in [1], this series is for addressing the KCSAN issues in
> sysctls.
>
> Following the tcp_congestion_control() model, patch 1 and 2 now store
> pointers to the immutable ops and swap them atomically via xchg().
>
> Patch 3 (from Matthieu) covers the remaining scalar sysctls with READ_ONCE().
>
> [1] https://github.com/multipath-tcp/mptcp_net-next/issues/626
Thank you for looking at that with Tao Cui.
Globally, it looks good to me, but I have a few small requests:
- Do you mind resending this series, please: for some unknown reasons,
Sashiko didn't get it. But before: ↓
- Can you not add Eric in Cc of the 3rd patch? Better not to spam him
for dev work → b4 send --no-trailer-to-cc ; or: git send-email
--suppress-cc=misc-by
- Could you split the code around bpf module support? I guess these
patches will be sent before adding BPF PM/sched support. In this case,
you would have squash-to patches for the BPF parts at the end of the series.
- I think you can move the WRITE_ONCE(pernet->pm_type, pm_type); from
current patch 2 to 3, with Tao Cui's Co-dev.
Cheers,
Matt
--
Sponsored by the NGI0 Core fund.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-08-17 17:43 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-08-17 1:24 [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls Gang Yan
2026-08-17 1:24 ` [PATCH mptcp-next 1/3] mptcp: sched: change scheduler sysctl atomically Gang Yan
2026-08-17 1:24 ` [PATCH mptcp-next 2/3] mptcp: pm: change path_manager " Gang Yan
2026-08-17 1:24 ` [PATCH mptcp-next 3/3] mptcp: use READ_ONCE() over sysctls Gang Yan
2026-08-17 2:31 ` [PATCH mptcp-next 0/3] mptcp: avoid data-races around the sysctls MPTCP CI
2026-08-17 17:43 ` Matthieu Baerts
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