aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorEric Dumazet <edumazet@google.com>2019-12-16 18:51:03 -0800
committerDavid S. Miller <davem@davemloft.net>2019-12-17 22:09:52 -0800
commit7c68fa2bddda6d942bd387c9ba5b4300737fd991 (patch)
tree3e77528920733f3ed1238495a95c87f9f5d59ac9
parentnet: qlogic: Fix error paths in ql_alloc_large_buffers() (diff)
downloadlinux-dev-7c68fa2bddda6d942bd387c9ba5b4300737fd991.tar.xz
linux-dev-7c68fa2bddda6d942bd387c9ba5b4300737fd991.zip
net: annotate lockless accesses to sk->sk_pacing_shift
sk->sk_pacing_shift can be read and written without lock synchronization. This patch adds annotations to document this fact and avoid future syzbot complains. This might also avoid unexpected false sharing in sk_pacing_shift_update(), as the compiler could remove the conditional check and always write over sk->sk_pacing_shift : if (sk->sk_pacing_shift != val) sk->sk_pacing_shift = val; Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
-rw-r--r--include/net/sock.h4
-rw-r--r--net/core/sock.c2
-rw-r--r--net/ipv4/tcp_bbr.c3
-rw-r--r--net/ipv4/tcp_output.c4
4 files changed, 7 insertions, 6 deletions
diff --git a/include/net/sock.h b/include/net/sock.h
index 04c274a20620..22be668457bf 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2588,9 +2588,9 @@ static inline int sk_get_rmem0(const struct sock *sk, const struct proto *proto)
*/
static inline void sk_pacing_shift_update(struct sock *sk, int val)
{
- if (!sk || !sk_fullsock(sk) || sk->sk_pacing_shift == val)
+ if (!sk || !sk_fullsock(sk) || READ_ONCE(sk->sk_pacing_shift) == val)
return;
- sk->sk_pacing_shift = val;
+ WRITE_ONCE(sk->sk_pacing_shift, val);
}
/* if a socket is bound to a device, check that the given device
diff --git a/net/core/sock.c b/net/core/sock.c
index 043db3ce023e..8459ad579f73 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2916,7 +2916,7 @@ void sock_init_data(struct socket *sock, struct sock *sk)
sk->sk_max_pacing_rate = ~0UL;
sk->sk_pacing_rate = ~0UL;
- sk->sk_pacing_shift = 10;
+ WRITE_ONCE(sk->sk_pacing_shift, 10);
sk->sk_incoming_cpu = -1;
sk_rx_queue_clear(sk);
diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index 32772d6ded4e..a6545ef0d27b 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -306,7 +306,8 @@ static u32 bbr_tso_segs_goal(struct sock *sk)
/* Sort of tcp_tso_autosize() but ignoring
* driver provided sk_gso_max_size.
*/
- bytes = min_t(unsigned long, sk->sk_pacing_rate >> sk->sk_pacing_shift,
+ bytes = min_t(unsigned long,
+ sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift),
GSO_MAX_SIZE - 1 - MAX_TCP_HEADER);
segs = max_t(u32, bytes / tp->mss_cache, bbr_min_tso_segs(sk));
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 36902d08473e..1f7735ca8f22 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1725,7 +1725,7 @@ static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now,
u32 bytes, segs;
bytes = min_t(unsigned long,
- sk->sk_pacing_rate >> sk->sk_pacing_shift,
+ sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift),
sk->sk_gso_max_size - 1 - MAX_TCP_HEADER);
/* Goal is to send at least one packet per ms,
@@ -2260,7 +2260,7 @@ static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb,
limit = max_t(unsigned long,
2 * skb->truesize,
- sk->sk_pacing_rate >> sk->sk_pacing_shift);
+ sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift));
if (sk->sk_pacing_status == SK_PACING_NONE)
limit = min_t(unsigned long, limit,
sock_net(sk)->ipv4.sysctl_tcp_limit_output_bytes);