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Subject[PATCH 5.12 032/161] net/tls: Replace TLS_RX_SYNC_RUNNING with RCU
Date
From: Maxim Mikityanskiy <maximmi@nvidia.com>

[ Upstream commit 05fc8b6cbd4f979a6f25759c4a17dd5f657f7ecd ]

RCU synchronization is guaranteed to finish in finite time, unlike a
busy loop that polls a flag. This patch is a preparation for the bugfix
in the next patch, where the same synchronize_net() call will also be
used to sync with the TX datapath.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/tls.h | 1 -
net/tls/tls_device.c | 10 +++-------
2 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/include/net/tls.h b/include/net/tls.h
index 3eccb525e8f7..6531ace2a68b 100644
--- a/include/net/tls.h
+++ b/include/net/tls.h
@@ -193,7 +193,6 @@ struct tls_offload_context_tx {
(sizeof(struct tls_offload_context_tx) + TLS_DRIVER_STATE_SIZE_TX)

enum tls_context_flags {
- TLS_RX_SYNC_RUNNING = 0,
/* Unlike RX where resync is driven entirely by the core in TX only
* the driver knows when things went out of sync, so we need the flag
* to be atomic.
diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index d9cd229aa111..2602d61a8d28 100644
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -680,15 +680,13 @@ static void tls_device_resync_rx(struct tls_context *tls_ctx,
struct tls_offload_context_rx *rx_ctx = tls_offload_ctx_rx(tls_ctx);
struct net_device *netdev;

- if (WARN_ON(test_and_set_bit(TLS_RX_SYNC_RUNNING, &tls_ctx->flags)))
- return;
-
trace_tls_device_rx_resync_send(sk, seq, rcd_sn, rx_ctx->resync_type);
+ rcu_read_lock();
netdev = READ_ONCE(tls_ctx->netdev);
if (netdev)
netdev->tlsdev_ops->tls_dev_resync(netdev, sk, seq, rcd_sn,
TLS_OFFLOAD_CTX_DIR_RX);
- clear_bit_unlock(TLS_RX_SYNC_RUNNING, &tls_ctx->flags);
+ rcu_read_unlock();
TLS_INC_STATS(sock_net(sk), LINUX_MIB_TLSRXDEVICERESYNC);
}

@@ -1300,9 +1298,7 @@ static int tls_device_down(struct net_device *netdev)
netdev->tlsdev_ops->tls_dev_del(netdev, ctx,
TLS_OFFLOAD_CTX_DIR_RX);
WRITE_ONCE(ctx->netdev, NULL);
- smp_mb__before_atomic(); /* pairs with test_and_set_bit() */
- while (test_bit(TLS_RX_SYNC_RUNNING, &ctx->flags))
- usleep_range(10, 200);
+ synchronize_net();
dev_put(netdev);
list_del_init(&ctx->list);

--
2.30.2


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