Re: [PATCH v8] eal_interrupts: add option for pending callback unregister

[Thomas Monjalon <thomas@monjalon.net>]

Someone for a review please?

17/12/2018 13:30, Jakub Grajciar:
> use case: if callback is used to receive message form socket,
> and the message received is disconnect/error, this callback needs
> to be unregistered, but cannot because it is still active.
> 
> With this patch it is possible to mark the callback to be
> unregistered once the interrupt process is done with this
> interrupt source.
> 
> Signed-off-by: Jakub Grajciar <jgrajcia@cisco.com>
> ---
>  .../common/include/rte_interrupts.h           | 32 +++++++
>  lib/librte_eal/linuxapp/eal/eal_interrupts.c  | 85 ++++++++++++++++++-
>  lib/librte_eal/rte_eal_version.map            |  1 +
>  3 files changed, 116 insertions(+), 2 deletions(-)
> 
> v2:
> - fix coding syle
> 
> v3:
> - fix locks
> 
> v4:
> - update version map
> 
> v6:
> - add _rte_experimental to rte_intr_callback_unregister_pending
> 
> v8:
> - fix compilation errors
> 
> diff --git a/lib/librte_eal/common/include/rte_interrupts.h b/lib/librte_eal/common/include/rte_interrupts.h
> index d751a6378..13d73a137 100644
> --- a/lib/librte_eal/common/include/rte_interrupts.h
> +++ b/lib/librte_eal/common/include/rte_interrupts.h
> @@ -6,6 +6,7 @@
>  #define _RTE_INTERRUPTS_H_
>  
>  #include <rte_common.h>
> +#include <rte_compat.h>
>  
>  /**
>   * @file
> @@ -24,6 +25,13 @@ struct rte_intr_handle;
>  /** Function to be registered for the specific interrupt */
>  typedef void (*rte_intr_callback_fn)(void *cb_arg);
>  
> +/**
> + * Function to call after a callback is unregistered.
> + * Can be used to close fd and free cb_arg.
> + */
> +typedef void (*rte_intr_unregister_callback_fn)(struct rte_intr_handle *intr_handle,
> +						void *cb_arg);
> +
>  #include "rte_eal_interrupts.h"
>  
>  /**
> @@ -61,6 +69,30 @@ int rte_intr_callback_register(const struct rte_intr_handle *intr_handle,
>  int rte_intr_callback_unregister(const struct rte_intr_handle *intr_handle,
>  				rte_intr_callback_fn cb, void *cb_arg);
>  
> +/**
> + * It unregisters the callback according to the specified interrupt handle,
> + * after it's no longer acive. Failes if source is not active.
> + *
> + * @param intr_handle
> + *  pointer to the interrupt handle.
> + * @param cb
> + *  callback address.
> + * @param cb_arg
> + *  address of parameter for callback, (void *)-1 means to remove all
> + *  registered which has the same callback address.
> + * @param ucb_fn
> + *  callback to call before cb is unregistered (optional).
> + *  can be used to close fd and free cb_arg.
> + *
> + * @return
> + *  - On success, return the number of callback entities marked for remove.
> + *  - On failure, a negative value.
> + */
> +int __rte_experimental
> +rte_intr_callback_unregister_pending(const struct rte_intr_handle *intr_handle,
> +				rte_intr_callback_fn cb_fn, void *cb_arg,
> +				rte_intr_unregister_callback_fn ucb_fn);
> +
>  /**
>   * It enables the interrupt for the specified handle.
>   *
> diff --git a/lib/librte_eal/linuxapp/eal/eal_interrupts.c b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> index cbac451e1..be0dd4490 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_interrupts.c
> @@ -76,6 +76,8 @@ struct rte_intr_callback {
>  	TAILQ_ENTRY(rte_intr_callback) next;
>  	rte_intr_callback_fn cb_fn;  /**< callback address */
>  	void *cb_arg;                /**< parameter for callback */
> +	uint8_t pending_delete;      /**< delete after callback is called */
> +	rte_intr_unregister_callback_fn ucb_fn; /**< fn to call before cb is deleted */
>  };
>  
>  struct rte_intr_source {
> @@ -472,6 +474,8 @@ rte_intr_callback_register(const struct rte_intr_handle *intr_handle,
>  	}
>  	callback->cb_fn = cb;
>  	callback->cb_arg = cb_arg;
> +	callback->pending_delete = 0;
> +	callback->ucb_fn = NULL;
>  
>  	rte_spinlock_lock(&intr_lock);
>  
> @@ -518,6 +522,57 @@ rte_intr_callback_register(const struct rte_intr_handle *intr_handle,
>  	return ret;
>  }
>  
> +int __rte_experimental
> +rte_intr_callback_unregister_pending(const struct rte_intr_handle *intr_handle,
> +				rte_intr_callback_fn cb_fn, void *cb_arg,
> +				rte_intr_unregister_callback_fn ucb_fn)
> +{
> +	int ret;
> +	struct rte_intr_source *src;
> +	struct rte_intr_callback *cb, *next;
> +
> +	/* do parameter checking first */
> +	if (intr_handle == NULL || intr_handle->fd < 0) {
> +		RTE_LOG(ERR, EAL,
> +		"Unregistering with invalid input parameter\n");
> +		return -EINVAL;
> +	}
> +
> +	rte_spinlock_lock(&intr_lock);
> +
> +	/* check if the insterrupt source for the fd is existent */
> +	TAILQ_FOREACH(src, &intr_sources, next)
> +		if (src->intr_handle.fd == intr_handle->fd)
> +			break;
> +
> +	/* No interrupt source registered for the fd */
> +	if (src == NULL) {
> +		ret = -ENOENT;
> +
> +	/* only usable if the source is active */
> +	} else if (src->active == 0) {
> +		ret = -EAGAIN;
> +
> +	} else {
> +		ret = 0;
> +
> +		/* walk through the callbacks and mark all that match. */
> +		for (cb = TAILQ_FIRST(&src->callbacks); cb != NULL; cb = next) {
> +			next = TAILQ_NEXT(cb, next);
> +			if (cb->cb_fn == cb_fn && (cb_arg == (void *)-1 ||
> +					cb->cb_arg == cb_arg)) {
> +				cb->pending_delete = 1;
> +				cb->ucb_fn = ucb_fn;
> +				ret++;
> +			}
> +		}
> +	}
> +
> +	rte_spinlock_unlock(&intr_lock);
> +
> +	return ret;
> +}
> +
>  int
>  rte_intr_callback_unregister(const struct rte_intr_handle *intr_handle,
>  			rte_intr_callback_fn cb_fn, void *cb_arg)
> @@ -698,7 +753,7 @@ static int
>  eal_intr_process_interrupts(struct epoll_event *events, int nfds)
>  {
>  	bool call = false;
> -	int n, bytes_read;
> +	int n, bytes_read, rv;
>  	struct rte_intr_source *src;
>  	struct rte_intr_callback *cb, *next;
>  	union rte_intr_read_buffer buf;
> @@ -823,9 +878,35 @@ eal_intr_process_interrupts(struct epoll_event *events, int nfds)
>  				rte_spinlock_lock(&intr_lock);
>  			}
>  		}
> -
>  		/* we done with that interrupt source, release it. */
>  		src->active = 0;
> +
> +		rv = 0;
> +
> +		/* check if any callback are supposed to be removed */
> +		for (cb = TAILQ_FIRST(&src->callbacks); cb != NULL; cb = next) {
> +			next = TAILQ_NEXT(cb, next);
> +			if (cb->pending_delete) {
> +				TAILQ_REMOVE(&src->callbacks, cb, next);
> +				if (cb->ucb_fn)
> +					cb->ucb_fn(&src->intr_handle, cb->cb_arg);
> +				free(cb);
> +				rv++;
> +			}
> +		}
> +
> +		/* all callbacks for that source are removed. */
> +		if (TAILQ_EMPTY(&src->callbacks)) {
> +			TAILQ_REMOVE(&intr_sources, src, next);
> +			free(src);
> +		}
> +
> +		/* notify the pipe fd waited by epoll_wait to rebuild the wait list */
> +		if (rv >= 0 && write(intr_pipe.writefd, "1", 1) < 0) {
> +			rte_spinlock_unlock(&intr_lock);
> +			return -EPIPE;
> +		}
> +
>  		rte_spinlock_unlock(&intr_lock);
>  	}
>  
> diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
> index 3fe78260d..989e4d72a 100644
> --- a/lib/librte_eal/rte_eal_version.map
> +++ b/lib/librte_eal/rte_eal_version.map
> @@ -318,6 +318,7 @@ EXPERIMENTAL {
>  	rte_fbarray_is_used;
>  	rte_fbarray_set_free;
>  	rte_fbarray_set_used;
> +	rte_intr_callback_unregister_pending;
>  	rte_log_register_type_and_pick_level;
>  	rte_malloc_dump_heaps;
>  	rte_malloc_heap_create;
>