5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ 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@google.com Cc: Abel Wu wuyun.abel@bytedance.com Reviewed-by: Shakeel Butt shakeelb@google.com Link: https://lore.kernel.org/r/20230818015132.2699348-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 61f5872aac24f..f73ef7087a187 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1161,6 +1161,7 @@ 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. */ @@ -1277,7 +1278,7 @@ 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) @@ -1289,7 +1290,7 @@ 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 @@ -1343,7 +1344,7 @@ 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 7cff1a031f761..431b9399a781f 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -97,7 +97,7 @@ 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); }