diff options
| author | Eric Dumazet <edumazet@google.com> | 2022-08-23 00:15:28 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2022-08-24 14:59:18 +0300 |
| commit | aacd467c0a576e5e44d2de4205855dc0fe43f6fb (patch) | |
| tree | b8e1bbe8a078cbabf46f376446e4a3906638e694 /net | |
| parent | 73ef239cd8439b33273cd95d08cffaf8022b01a8 (diff) | |
| download | linux-aacd467c0a576e5e44d2de4205855dc0fe43f6fb.tar.xz | |
tcp: annotate data-race around tcp_md5sig_pool_populated
tcp_md5sig_pool_populated can be read while another thread
changes its value.
The race has no consequence because allocations
are protected with tcp_md5sig_mutex.
This patch adds READ_ONCE() and WRITE_ONCE() to document
the race and silence KCSAN.
Reported-by: Abhishek Shah <abhishek.shah@columbia.edu>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index bbe218753662..ba62f8e8bd15 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4433,12 +4433,16 @@ static void __tcp_alloc_md5sig_pool(void) * to memory. See smp_rmb() in tcp_get_md5sig_pool() */ smp_wmb(); - tcp_md5sig_pool_populated = true; + /* Paired with READ_ONCE() from tcp_alloc_md5sig_pool() + * and tcp_get_md5sig_pool(). + */ + WRITE_ONCE(tcp_md5sig_pool_populated, true); } bool tcp_alloc_md5sig_pool(void) { - if (unlikely(!tcp_md5sig_pool_populated)) { + /* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */ + if (unlikely(!READ_ONCE(tcp_md5sig_pool_populated))) { mutex_lock(&tcp_md5sig_mutex); if (!tcp_md5sig_pool_populated) { @@ -4449,7 +4453,8 @@ bool tcp_alloc_md5sig_pool(void) mutex_unlock(&tcp_md5sig_mutex); } - return tcp_md5sig_pool_populated; + /* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */ + return READ_ONCE(tcp_md5sig_pool_populated); } EXPORT_SYMBOL(tcp_alloc_md5sig_pool); @@ -4465,7 +4470,8 @@ struct tcp_md5sig_pool *tcp_get_md5sig_pool(void) { local_bh_disable(); - if (tcp_md5sig_pool_populated) { + /* Paired with WRITE_ONCE() from __tcp_alloc_md5sig_pool() */ + if (READ_ONCE(tcp_md5sig_pool_populated)) { /* coupled with smp_wmb() in __tcp_alloc_md5sig_pool() */ smp_rmb(); return this_cpu_ptr(&tcp_md5sig_pool); |