Message ID | 20201002000711.41511-2-honnappa.nagarahalli@arm.com |
---|---|
State | Superseded |
Headers | show |
Series | [1/2] lib/ethdev: replace full barrier with relaxed barrier | expand |
> -----Original Message----- > From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com> > Sent: Friday, October 2, 2020 8:07 AM > To: dev@dpdk.org; Honnappa Nagarahalli > <Honnappa.Nagarahalli@arm.com>; Phil Yang <Phil.Yang@arm.com>; > thomas@monjalon.net; arybchenko@solarflare.com; ferruh.yigit@intel.com > Cc: abhinandan.gujjar@intel.com; nd <nd@arm.com>; > bruce.richardson@intel.com; john.mcnamara@intel.com; > reshma.pattan@intel.com; stable@dpdk.org > Subject: [PATCH 2/2] lib/ethdev: fix memory ordering for call back functions > > 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: 4dc294158cac ("ethdev: support optional Rx and Tx callbacks") > Fixes: c8231c63ddcb ("ethdev: insert Rx callback as head of list") > Cc: bruce.richardson@intel.com > Cc: john.mcnamara@intel.com > Cc: reshma.pattan@intel.com > 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> > --- > lib/librte_ethdev/rte_ethdev.c | 28 +++++++++++++++++++++------ > lib/librte_ethdev/rte_ethdev.h | 35 ++++++++++++++++++++++++++------- > - > 2 files changed, 49 insertions(+), 14 deletions(-) > > diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c > index 59a41c07f..d89fcdc77 100644 > --- a/lib/librte_ethdev/rte_ethdev.c > +++ b/lib/librte_ethdev/rte_ethdev.c > @@ -4486,12 +4486,20 @@ 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); > > @@ -4576,12 +4584,20 @@ 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); > > @@ -4612,7 +4628,7 @@ 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; > } > @@ -4646,7 +4662,7 @@ 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; > } > diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h > index 70295d7ab..d810e3e38 100644 > --- a/lib/librte_ethdev/rte_ethdev.h > +++ b/lib/librte_ethdev/rte_ethdev.h > @@ -3734,7 +3734,8 @@ 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. > @@ -3763,7 +3764,8 @@ 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. > @@ -3791,7 +3793,8 @@ 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. > @@ -3816,7 +3819,9 @@ 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. > @@ -3849,7 +3854,9 @@ 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. > @@ -4510,10 +4517,16 @@ 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]; > + /* __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. > + */ > + struct rte_eth_rxtx_callback *cb = > + dev->post_rx_burst_cbs[queue_id]; > > + if (unlikely(cb != NULL)) { > do { > nb_rx = cb->fn.rx(port_id, queue_id, rx_pkts, nb_rx, > nb_pkts, cb->param); > @@ -4775,6 +4788,12 @@ rte_eth_tx_burst(uint16_t port_id, uint16_t > queue_id, > #endif > > #ifdef RTE_ETHDEV_RXTX_CALLBACKS > + /* __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. > + */ > struct rte_eth_rxtx_callback *cb = dev- > >pre_tx_burst_cbs[queue_id]; > > if (unlikely(cb != NULL)) { > -- > 2.17.1
On 10/2/2020 1:07 AM, Honnappa Nagarahalli wrote: > 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: 4dc294158cac ("ethdev: support optional Rx and Tx callbacks") > Fixes: c8231c63ddcb ("ethdev: insert Rx callback as head of list") > Cc: bruce.richardson@intel.com > Cc: john.mcnamara@intel.com > Cc: reshma.pattan@intel.com > Cc: stable@dpdk.org > > Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com> > Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com> +Konstantin & Jerin, Can you please help reviewing this one too? @Honnappa, Is this patch supersedes the following one in the queue by ZY Qiu: https://patches.dpdk.org/patch/66301/
> > 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: 4dc294158cac ("ethdev: support optional Rx and Tx callbacks") > Fixes: c8231c63ddcb ("ethdev: insert Rx callback as head of list") > Cc: bruce.richardson@intel.com > Cc: john.mcnamara@intel.com > Cc: reshma.pattan@intel.com > Cc: stable@dpdk.org > > Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com> > Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com> > --- > lib/librte_ethdev/rte_ethdev.c | 28 +++++++++++++++++++++------ > lib/librte_ethdev/rte_ethdev.h | 35 ++++++++++++++++++++++++++-------- > 2 files changed, 49 insertions(+), 14 deletions(-) > > diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c > index 59a41c07f..d89fcdc77 100644 > --- a/lib/librte_ethdev/rte_ethdev.c > +++ b/lib/librte_ethdev/rte_ethdev.c > @@ -4486,12 +4486,20 @@ 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); > > @@ -4576,12 +4584,20 @@ 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); > > @@ -4612,7 +4628,7 @@ 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; > } > @@ -4646,7 +4662,7 @@ 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; > } > diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h > index 70295d7ab..d810e3e38 100644 > --- a/lib/librte_ethdev/rte_ethdev.h > +++ b/lib/librte_ethdev/rte_ethdev.h > @@ -3734,7 +3734,8 @@ 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. > @@ -3763,7 +3764,8 @@ 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. > @@ -3791,7 +3793,8 @@ 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. > @@ -3816,7 +3819,9 @@ 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. > @@ -3849,7 +3854,9 @@ 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. > @@ -4510,10 +4517,16 @@ 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]; > + /* __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. > + */ > + struct rte_eth_rxtx_callback *cb = > + dev->post_rx_burst_cbs[queue_id]; > > + if (unlikely(cb != NULL)) { > do { > nb_rx = cb->fn.rx(port_id, queue_id, rx_pkts, nb_rx, > nb_pkts, cb->param); > @@ -4775,6 +4788,12 @@ rte_eth_tx_burst(uint16_t port_id, uint16_t queue_id, > #endif > > #ifdef RTE_ETHDEV_RXTX_CALLBACKS > + /* __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. > + */ > struct rte_eth_rxtx_callback *cb = dev->pre_tx_burst_cbs[queue_id]; > > if (unlikely(cb != NULL)) { > -- Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com> > 2.17.1
<snip> > Subject: Re: [PATCH 2/2] lib/ethdev: fix memory ordering for call back > functions > > On 10/2/2020 1:07 AM, Honnappa Nagarahalli wrote: > > 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: 4dc294158cac ("ethdev: support optional Rx and Tx callbacks") > > Fixes: c8231c63ddcb ("ethdev: insert Rx callback as head of list") > > Cc: bruce.richardson@intel.com > > Cc: john.mcnamara@intel.com > > Cc: reshma.pattan@intel.com > > Cc: stable@dpdk.org > > > > Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com> > > Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com> > > +Konstantin & Jerin, > > Can you please help reviewing this one too? > > @Honnappa, > > Is this patch supersedes the following one in the queue by ZY Qiu: > https://patches.dpdk.org/patch/66301/ Yes, my patch should supersede. I will create a V2 to address the issue ZY Qiu's patch is trying to address.
diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c index 59a41c07f..d89fcdc77 100644 --- a/lib/librte_ethdev/rte_ethdev.c +++ b/lib/librte_ethdev/rte_ethdev.c @@ -4486,12 +4486,20 @@ 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); @@ -4576,12 +4584,20 @@ 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); @@ -4612,7 +4628,7 @@ 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; } @@ -4646,7 +4662,7 @@ 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; } diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h index 70295d7ab..d810e3e38 100644 --- a/lib/librte_ethdev/rte_ethdev.h +++ b/lib/librte_ethdev/rte_ethdev.h @@ -3734,7 +3734,8 @@ 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. @@ -3763,7 +3764,8 @@ 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. @@ -3791,7 +3793,8 @@ 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. @@ -3816,7 +3819,9 @@ 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. @@ -3849,7 +3854,9 @@ 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. @@ -4510,10 +4517,16 @@ 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]; + /* __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. + */ + struct rte_eth_rxtx_callback *cb = + dev->post_rx_burst_cbs[queue_id]; + if (unlikely(cb != NULL)) { do { nb_rx = cb->fn.rx(port_id, queue_id, rx_pkts, nb_rx, nb_pkts, cb->param); @@ -4775,6 +4788,12 @@ rte_eth_tx_burst(uint16_t port_id, uint16_t queue_id, #endif #ifdef RTE_ETHDEV_RXTX_CALLBACKS + /* __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. + */ struct rte_eth_rxtx_callback *cb = dev->pre_tx_burst_cbs[queue_id]; if (unlikely(cb != NULL)) {