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charset=UTF-8 Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On 01/02/2024 08:43, David Marchand wrote: > As described in a recent bugzilla opened against the net/iavf driver, > a driver may call a event callback from other calls of the ethdev API. > > Nothing guarantees in the ethdev API against such behavior. > > Add a notice against using locks in those callbacks. > > Bugzilla ID: 1337 > > Signed-off-by: David Marchand > --- > lib/ethdev/rte_ethdev.h | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h > index 21e3a21903..5c6b104fb4 100644 > --- a/lib/ethdev/rte_ethdev.h > +++ b/lib/ethdev/rte_ethdev.h > @@ -4090,7 +4090,19 @@ enum rte_eth_event_type { > RTE_ETH_EVENT_MAX /**< max value of this enum */ > }; > > -/** User application callback to be registered for interrupts. */ > +/** > + * User application callback to be registered for interrupts. > + * > + * Note: there is no guarantee in the DPDK drivers that a callback won't be > + * called in the middle of other parts of the ethdev API. For example, > + * imagine that thread A calls rte_eth_dev_start() and as part of this > + * call, a RTE_ETH_EVENT_INTR_RESET event gets generated and the > + * associated callback is ran on thread A. In that example, if the > + * application protects its internal data using locks before calling > + * rte_eth_dev_start(), and the callback takes a same lock, a deadlock > + * occurs. Because of this, it is highly recommended NOT to take locks in > + * those callbacks. > + */ That is a good practical recommendation for an application developer. I wonder if it should taken further so that the API formally states the callback MUST be non-blocking? > typedef int (*rte_eth_dev_cb_fn)(uint16_t port_id, > enum rte_eth_event_type event, void *cb_arg, void *ret_param); >