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ethdev: fix memory ordering for callback functions

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Call back functions are registered on the control plane. They
are accessed from the data plane. Hence, correct memory orderings
should be used to avoid race conditions.

Fixes: 4dc294158c ("ethdev: support optional Rx and Tx callbacks")
Fixes: c8231c63dd ("ethdev: insert Rx callback as head of list")
Cc: stable@dpdk.org

Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
Reviewed-by: Phil Yang <phil.yang@arm.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
This commit is contained in:
Honnappa Nagarahalli 2020-10-13 11:25:37 -05:00 committed by Ferruh Yigit
parent 8dd4b2afc7
commit 2b69bd1179
2 changed files with 55 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
lib/librte_ethdev/rte_ethdev.c
View File

@ -4610,12 +4610,20 @@ rte_eth_add_rx_callback(uint16_t port_id, uint16_t queue_id,
rte_eth_devices[port_id].post_rx_burst_cbs[queue_id];
if (!tail) {
rte_eth_devices[port_id].post_rx_burst_cbs[queue_id] = cb;
/* Stores to cb->fn and cb->param should complete before
* cb is visible to data plane.
*/
__atomic_store_n(
&rte_eth_devices[port_id].post_rx_burst_cbs[queue_id],
cb, __ATOMIC_RELEASE);
} else {
while (tail->next)
tail = tail->next;
tail->next = cb;
/* Stores to cb->fn and cb->param should complete before
* cb is visible to data plane.
*/
__atomic_store_n(&tail->next, cb, __ATOMIC_RELEASE);
}
rte_spinlock_unlock(&rte_eth_rx_cb_lock);
@ -4700,12 +4708,20 @@ rte_eth_add_tx_callback(uint16_t port_id, uint16_t queue_id,
rte_eth_devices[port_id].pre_tx_burst_cbs[queue_id];
if (!tail) {
rte_eth_devices[port_id].pre_tx_burst_cbs[queue_id] = cb;
/* Stores to cb->fn and cb->param should complete before
* cb is visible to data plane.
*/
__atomic_store_n(
&rte_eth_devices[port_id].pre_tx_burst_cbs[queue_id],
cb, __ATOMIC_RELEASE);
} else {
while (tail->next)
tail = tail->next;
tail->next = cb;
/* Stores to cb->fn and cb->param should complete before
* cb is visible to data plane.
*/
__atomic_store_n(&tail->next, cb, __ATOMIC_RELEASE);
}
rte_spinlock_unlock(&rte_eth_tx_cb_lock);
@ -4736,7 +4752,7 @@ rte_eth_remove_rx_callback(uint16_t port_id, uint16_t queue_id,
cb = *prev_cb;
if (cb == user_cb) {
/* Remove the user cb from the callback list. */
*prev_cb = cb->next;
__atomic_store_n(prev_cb, cb->next, __ATOMIC_RELAXED);
ret = 0;
break;
}
@ -4770,7 +4786,7 @@ rte_eth_remove_tx_callback(uint16_t port_id, uint16_t queue_id,
cb = *prev_cb;
if (cb == user_cb) {
/* Remove the user cb from the callback list. */
*prev_cb = cb->next;
__atomic_store_n(prev_cb, cb->next, __ATOMIC_RELAXED);
ret = 0;
break;
}

42
lib/librte_ethdev/rte_ethdev.h
View File

@ -3911,7 +3911,8 @@ struct rte_eth_rxtx_callback;
* The callback function
* @param user_param
* A generic pointer parameter which will be passed to each invocation of the
* callback function on this port and queue.
* callback function on this port and queue. Inter-thread synchronization
* of any user data changes is the responsibility of the user.
*
* @return
* NULL on error.
@ -3940,7 +3941,8 @@ rte_eth_add_rx_callback(uint16_t port_id, uint16_t queue_id,
* The callback function
* @param user_param
* A generic pointer parameter which will be passed to each invocation of the
* callback function on this port and queue.
* callback function on this port and queue. Inter-thread synchronization
* of any user data changes is the responsibility of the user.
*
* @return
* NULL on error.
@ -3968,7 +3970,8 @@ rte_eth_add_first_rx_callback(uint16_t port_id, uint16_t queue_id,
* The callback function
* @param user_param
* A generic pointer parameter which will be passed to each invocation of the
* callback function on this port and queue.
* callback function on this port and queue. Inter-thread synchronization
* of any user data changes is the responsibility of the user.
*
* @return
* NULL on error.
@ -3993,7 +3996,9 @@ rte_eth_add_tx_callback(uint16_t port_id, uint16_t queue_id,
* on that queue.
*
* - After a short delay - where the delay is sufficient to allow any
* in-flight callbacks to complete.
* in-flight callbacks to complete. Alternately, the RCU mechanism can be
* used to detect when data plane threads have ceased referencing the
* callback memory.
*
* @param port_id
* The port identifier of the Ethernet device.
@ -4026,7 +4031,9 @@ int rte_eth_remove_rx_callback(uint16_t port_id, uint16_t queue_id,
* on that queue.
*
* - After a short delay - where the delay is sufficient to allow any
* in-flight callbacks to complete.
* in-flight callbacks to complete. Alternately, the RCU mechanism can be
* used to detect when data plane threads have ceased referencing the
* callback memory.
*
* @param port_id
* The port identifier of the Ethernet device.
@ -4687,10 +4694,18 @@ rte_eth_rx_burst(uint16_t port_id, uint16_t queue_id,
rx_pkts, nb_pkts);
#ifdef RTE_ETHDEV_RXTX_CALLBACKS
if (unlikely(dev->post_rx_burst_cbs[queue_id] != NULL)) {
struct rte_eth_rxtx_callback *cb =
dev->post_rx_burst_cbs[queue_id];
struct rte_eth_rxtx_callback *cb;
/* __ATOMIC_RELEASE memory order was used when the
* call back was inserted into the list.
* Since there is a clear dependency between loading
* cb and cb->fn/cb->next, __ATOMIC_ACQUIRE memory order is
* not required.
*/
cb = __atomic_load_n(&dev->post_rx_burst_cbs[queue_id],
__ATOMIC_RELAXED);
if (unlikely(cb != NULL)) {
do {
nb_rx = cb->fn.rx(port_id, queue_id, rx_pkts, nb_rx,
nb_pkts, cb->param);
@ -4953,7 +4968,16 @@ rte_eth_tx_burst(uint16_t port_id, uint16_t queue_id,
#endif
#ifdef RTE_ETHDEV_RXTX_CALLBACKS
struct rte_eth_rxtx_callback *cb = dev->pre_tx_burst_cbs[queue_id];
struct rte_eth_rxtx_callback *cb;
/* __ATOMIC_RELEASE memory order was used when the
* call back was inserted into the list.
* Since there is a clear dependency between loading
* cb and cb->fn/cb->next, __ATOMIC_ACQUIRE memory order is
* not required.
*/
cb = __atomic_load_n(&dev->pre_tx_burst_cbs[queue_id],
__ATOMIC_RELAXED);
if (unlikely(cb != NULL)) {
do {