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tcp_metrics: annotate data-races around tm->tcpm_vals[]

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tm->tcpm_vals[] values can be read or written locklessly.

Add needed READ_ONCE()/WRITE_ONCE() to document this,
and force use of tcp_metric_get() and tcp_metric_set()

Fixes: 51c5d0c4b1 ("tcp: Maintain dynamic metrics in local cache.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2023-08-02 13:14:58 +00:00 committed by Jakub Kicinski
parent 285ce119a3
commit 8c4d04f6b4
1 changed files with 14 additions and 9 deletions
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23
net/ipv4/tcp_metrics.c
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@ -63,17 +63,19 @@ static bool tcp_metric_locked(struct tcp_metrics_block *tm,
return READ_ONCE(tm->tcpm_lock) & (1 << idx);
}
static u32 tcp_metric_get(struct tcp_metrics_block *tm,
static u32 tcp_metric_get(const struct tcp_metrics_block *tm,
enum tcp_metric_index idx)
{
return tm->tcpm_vals[idx];
/* Paired with WRITE_ONCE() in tcp_metric_set() */
return READ_ONCE(tm->tcpm_vals[idx]);
}
static void tcp_metric_set(struct tcp_metrics_block *tm,
enum tcp_metric_index idx,
u32 val)
{
tm->tcpm_vals[idx] = val;
/* Paired with READ_ONCE() in tcp_metric_get() */
WRITE_ONCE(tm->tcpm_vals[idx], val);
}
static bool addr_same(const struct inetpeer_addr *a,
@ -115,13 +117,16 @@ static void tcpm_suck_dst(struct tcp_metrics_block *tm,
WRITE_ONCE(tm->tcpm_lock, val);
msval = dst_metric_raw(dst, RTAX_RTT);
tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;
tcp_metric_set(tm, TCP_METRIC_RTT, msval * USEC_PER_MSEC);
msval = dst_metric_raw(dst, RTAX_RTTVAR);
tm->tcpm_vals[TCP_METRIC_RTTVAR] = msval * USEC_PER_MSEC;
tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
tcp_metric_set(tm, TCP_METRIC_RTTVAR, msval * USEC_PER_MSEC);
tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
dst_metric_raw(dst, RTAX_SSTHRESH));
tcp_metric_set(tm, TCP_METRIC_CWND,
dst_metric_raw(dst, RTAX_CWND));
tcp_metric_set(tm, TCP_METRIC_REORDERING,
dst_metric_raw(dst, RTAX_REORDERING));
if (fastopen_clear) {
tm->tcpm_fastopen.mss = 0;
tm->tcpm_fastopen.syn_loss = 0;
@ -667,7 +672,7 @@ static int tcp_metrics_fill_info(struct sk_buff *msg,
if (!nest)
goto nla_put_failure;
for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
u32 val = tm->tcpm_vals[i];
u32 val = tcp_metric_get(tm, i);
if (!val)
continue;