4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 76f33296d2e09f63118db78125c95ef56df438e9 ]
*prot->memory_pressure is read/writen locklessly, we need
to add proper annotations.
A recent commit added a new race, it is time to audit all accesses.
Fixes: 2d0c88e84e48 ("sock: Fix misuse of sk_under_memory_pressure()")
Fixes: 4d93df0abd50 ("[SCTP]: Rewrite of sctp buffer management code")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Abel Wu <wuyun.abel@xxxxxxxxxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230818015132.2699348-1-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
include/net/sock.h | 7 ++++---
net/sctp/socket.c | 2 +-
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index bcb1901ac13a5..373e34b46a3c9 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1152,6 +1152,7 @@ struct proto {
/*
* Pressure flag: try to collapse.
* Technical note: it is used by multiple contexts non atomically.
+ * Make sure to use READ_ONCE()/WRITE_ONCE() for all reads/writes.
* All the __sk_mem_schedule() is of this nature: accounting
* is strict, actions are advisory and have some latency.
*/
@@ -1268,7 +1269,7 @@ static inline bool sk_has_memory_pressure(const struct sock *sk)
static inline bool sk_under_global_memory_pressure(const struct sock *sk)
{
return sk->sk_prot->memory_pressure &&
- !!*sk->sk_prot->memory_pressure;
+ !!READ_ONCE(*sk->sk_prot->memory_pressure);
}
static inline bool sk_under_memory_pressure(const struct sock *sk)
@@ -1280,7 +1281,7 @@ static inline bool sk_under_memory_pressure(const struct sock *sk)
mem_cgroup_under_socket_pressure(sk->sk_memcg))
return true;
- return !!*sk->sk_prot->memory_pressure;
+ return !!READ_ONCE(*sk->sk_prot->memory_pressure);
}
static inline long
@@ -1334,7 +1335,7 @@ proto_memory_pressure(struct proto *prot)
{
if (!prot->memory_pressure)
return false;
- return !!*prot->memory_pressure;
+ return !!READ_ONCE(*prot->memory_pressure);
}
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index baa825751c393..432dccd375064 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -112,7 +112,7 @@ struct percpu_counter sctp_sockets_allocated;
static void sctp_enter_memory_pressure(struct sock *sk)
{
- sctp_memory_pressure = 1;
+ WRITE_ONCE(sctp_memory_pressure, 1);
}
--
2.40.1
