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authorDeepa Dinamani <deepa.kernel@gmail.com>2018-12-27 18:55:09 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-01-09 17:14:46 +0100
commite5af70e98abbdbf7a22f897344d806494715cfb3 (patch)
tree85f18cd41c96f78187d7439647c0e3a3aad8d334 /net/sunrpc
parent952dea5bc0b43bd26412455f32651f34f8e7ccff (diff)
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sock: Make sock->sk_stamp thread-safe
[ Upstream commit 3a0ed3e9619738067214871e9cb826fa23b2ddb9 ] Al Viro mentioned (Message-ID <20170626041334.GZ10672@ZenIV.linux.org.uk>) that there is probably a race condition lurking in accesses of sk_stamp on 32-bit machines. sock->sk_stamp is of type ktime_t which is always an s64. On a 32 bit architecture, we might run into situations of unsafe access as the access to the field becomes non atomic. Use seqlocks for synchronization. This allows us to avoid using spinlocks for readers as readers do not need mutual exclusion. Another approach to solve this is to require sk_lock for all modifications of the timestamps. The current approach allows for timestamps to have their own lock: sk_stamp_lock. This allows for the patch to not compete with already existing critical sections, and side effects are limited to the paths in the patch. The addition of the new field maintains the data locality optimizations from commit 9115e8cd2a0c ("net: reorganize struct sock for better data locality") Note that all the instances of the sk_stamp accesses are either through the ioctl or the syscall recvmsg. Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/svcsock.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index ff8e06cd067e..c83df30e9655 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -585,7 +585,7 @@ static int svc_udp_recvfrom(struct svc_rqst *rqstp)
/* Don't enable netstamp, sunrpc doesn't
need that much accuracy */
}
- svsk->sk_sk->sk_stamp = skb->tstamp;
+ sock_write_timestamp(svsk->sk_sk, skb->tstamp);
set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags); /* there may be more data... */
len = skb->len;