Commit d83e4762 authored by Ben Walker's avatar Ben Walker Committed by Jim Harris
Browse files

util: Add spdk_fd_group_nest() and spdk_fd_group_unnest 



These provide a way to nest one fd_group into another in a more
efficient manner than just adding the fd_group's fd to the parent. It
also keeps track of which events belong to which group, so the unnest
operation can be implemented.

Change-Id: I63d63365f1160cce8b4b6388a0ea2003ef424b9e
Signed-off-by: default avatarBen Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/15473


Reviewed-by: default avatarKonrad Sztyber <konrad.sztyber@intel.com>
Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Mellanox Build Bot
parent acad3355

include/spdk/fd_group.h

+24 −0
Original line number Diff line number Diff line
@@ -75,6 +75,30 @@ int spdk_fd_group_wait(struct spdk_fd_group *fgrp, int timeout); 
 */

int spdk_fd_group_get_fd(struct spdk_fd_group *fgrp);



/**

 * Nest the child fd_group in the parent fd_group. After this operation

 * completes, calling spdk_fd_group_wait() on the parent will include events

 * from the child.

 *

 * \param parent The parent fd_group.

 * \param child The child fd_group.

 *

 * \return 0 on success. Negated errno on failure. However, on all errno values other

 * than -ENOTRECOVERABLE, the operation has not changed the state of the fd_group.

 */

int spdk_fd_group_nest(struct spdk_fd_group *parent, struct spdk_fd_group *child);



/**

 * Remove the nested child from the parent.

 *

 * \param parent The parent fd_group.

 * \param child The child fd_group.

 *

 * \return 0 on success. Negated errno on failure. However, on all errno values other

 * than -ENOTRECOVERABLE, the operation has not changed the state of the fd_group.

 */

int spdk_fd_group_unnest(struct spdk_fd_group *parent, struct spdk_fd_group *child);



/**

 * Register one event source to specified fgrp.

 *

lib/util/fd_group.c

+204 −5
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ struct event_handler { 
	void				*fn_arg;

	/* file descriptor of the interrupt event */

	int				fd;

	uint32_t			events;

	char				name[SPDK_MAX_EVENT_NAME_LEN + 1];

};
@@ -48,6 +49,8 @@ struct spdk_fd_group { 
	int epfd;

	int num_fds; /* Number of fds registered in this group. */



	struct spdk_fd_group *parent;



	/* interrupt sources list */

	TAILQ_HEAD(, event_handler) event_handlers;

};
@@ -72,6 +75,155 @@ spdk_fd_group_get_epoll_event(struct epoll_event *event) 
	return 0;

}



static int

_fd_group_del_all(int epfd, struct spdk_fd_group *grp)

{

	struct event_handler *ehdlr = NULL;

	struct epoll_event epevent = {0};

	int rc;

	int ret = 0;



	TAILQ_FOREACH(ehdlr, &grp->event_handlers, next) {

		rc = epoll_ctl(epfd, EPOLL_CTL_DEL, ehdlr->fd, NULL);

		if (rc < 0) {

			if (errno == ENOENT) {

				/* This is treated as success. It happens if there are multiple

				 * attempts to remove fds from the group.

				 */

				continue;

			}



			ret = -errno;

			SPDK_ERRLOG("Failed to remove fd %d from group: %s\n", ehdlr->fd, strerror(errno));

			goto recover;

		}

	}



	return 0;



recover:

	/* We failed to remove everything. Let's try to get everything put back into

	 * the original group. */

	TAILQ_FOREACH(ehdlr, &grp->event_handlers, next) {

		epevent.events = ehdlr->events;

		epevent.data.ptr = ehdlr;

		rc = epoll_ctl(epfd, EPOLL_CTL_ADD, ehdlr->fd, &epevent);

		if (rc < 0) {

			if (errno == EEXIST) {

				/* This is fine. Keep going. */

				continue;

			}



			/* Continue on even though we've failed. But indicate

			 * this is a fatal error. */

			SPDK_ERRLOG("Failed to recover fd_group_del_all: %s\n", strerror(errno));

			ret = -ENOTRECOVERABLE;

		}

	}



	return ret;

}



static int

_fd_group_add_all(int epfd, struct spdk_fd_group *grp)

{

	struct event_handler *ehdlr = NULL;

	struct epoll_event epevent = {0};

	int rc;

	int ret = 0;



	/* Hoist the fds from the child up into the parent */

	TAILQ_FOREACH(ehdlr, &grp->event_handlers, next) {

		epevent.events = ehdlr->events;

		epevent.data.ptr = ehdlr;

		rc = epoll_ctl(epfd, EPOLL_CTL_ADD, ehdlr->fd, &epevent);

		if (rc < 0) {

			if (errno == EEXIST) {

				/* This is treated as success */

				continue;

			}



			ret = -errno;

			SPDK_ERRLOG("Failed to add fd to fd group: %s\n", strerror(errno));

			goto recover;

		}

	}



	return 0;



recover:

	/* We failed to add everything, so try to remove what we did add. */

	TAILQ_FOREACH(ehdlr, &grp->event_handlers, next) {

		rc = epoll_ctl(epfd, EPOLL_CTL_DEL, ehdlr->fd, NULL);

		if (rc < 0) {

			if (errno == ENOENT) {

				/* This is treated as success. */

				continue;

			}





			/* Continue on even though we've failed. But indicate

			 * this is a fatal error. */

			SPDK_ERRLOG("Failed to recover fd_group_del_all: %s\n", strerror(errno));

			ret = -ENOTRECOVERABLE;

		}

	}



	return ret;

}



int

spdk_fd_group_unnest(struct spdk_fd_group *parent, struct spdk_fd_group *child)

{

	int rc;



	if (parent == NULL || child == NULL) {

		return -EINVAL;

	}



	if (child->parent != parent) {

		return -EINVAL;

	}



	rc = _fd_group_del_all(parent->epfd, child);

	if (rc < 0) {

		return rc;

	}



	child->parent = NULL;



	return _fd_group_add_all(child->epfd, child);

}



int

spdk_fd_group_nest(struct spdk_fd_group *parent, struct spdk_fd_group *child)

{

	int rc;



	if (parent == NULL || child == NULL) {

		return -EINVAL;

	}



	if (child->parent) {

		return -EINVAL;

	}



	if (parent->parent) {

		/* More than one layer of nesting is not currently supported */

		assert(false);

		return -ENOTSUP;

	}



	rc = _fd_group_del_all(child->epfd, child);

	if (rc < 0) {

		return rc;

	}



	child->parent = parent;



	return _fd_group_add_all(parent->epfd, child);

}



int

spdk_fd_group_add(struct spdk_fd_group *fgrp, int efd, spdk_fd_fn fn,

		  void *arg, const char *name)
@@ -79,6 +231,7 @@ spdk_fd_group_add(struct spdk_fd_group *fgrp, int efd, spdk_fd_fn fn, 
	struct event_handler *ehdlr = NULL;

	struct epoll_event epevent = {0};

	int rc;

	int epfd;



	/* parameter checking */

	if (fgrp == NULL || efd < 0 || fn == NULL) {
@@ -102,11 +255,18 @@ spdk_fd_group_add(struct spdk_fd_group *fgrp, int efd, spdk_fd_fn fn, 
	ehdlr->fn = fn;

	ehdlr->fn_arg = arg;

	ehdlr->state = EVENT_HANDLER_STATE_WAITING;

	ehdlr->events = EPOLLIN;

	snprintf(ehdlr->name, sizeof(ehdlr->name), "%s", name);



	epevent.events = EPOLLIN;

	if (fgrp->parent) {

		epfd = fgrp->parent->epfd;

	} else {

		epfd = fgrp->epfd;

	}



	epevent.events = ehdlr->events;

	epevent.data.ptr = ehdlr;

	rc = epoll_ctl(fgrp->epfd, EPOLL_CTL_ADD, efd, &epevent);

	rc = epoll_ctl(epfd, EPOLL_CTL_ADD, efd, &epevent);

	if (rc < 0) {

		free(ehdlr);

		return -errno;
@@ -123,6 +283,7 @@ spdk_fd_group_remove(struct spdk_fd_group *fgrp, int efd) 
{

	struct event_handler *ehdlr;

	int rc;

	int epfd;



	if (fgrp == NULL || efd < 0) {

		SPDK_ERRLOG("Invalid to remvoe efd(%d) from fd_group(%p).\n", efd, fgrp);
@@ -144,7 +305,13 @@ spdk_fd_group_remove(struct spdk_fd_group *fgrp, int efd) 


	assert(ehdlr->state != EVENT_HANDLER_STATE_REMOVED);



	rc = epoll_ctl(fgrp->epfd, EPOLL_CTL_DEL, ehdlr->fd, NULL);

	if (fgrp->parent) {

		epfd = fgrp->parent->epfd;

	} else {

		epfd = fgrp->epfd;

	}



	rc = epoll_ctl(epfd, EPOLL_CTL_DEL, ehdlr->fd, NULL);

	if (rc < 0) {

		SPDK_ERRLOG("Failed to delete the fd(%d) from the epoll group(%p)\n", efd, fgrp);

		return;
@@ -168,6 +335,7 @@ spdk_fd_group_event_modify(struct spdk_fd_group *fgrp, 
{

	struct epoll_event epevent;

	struct event_handler *ehdlr;

	int epfd;



	if (fgrp == NULL || efd < 0) {

		return -EINVAL;
@@ -185,10 +353,18 @@ spdk_fd_group_event_modify(struct spdk_fd_group *fgrp, 


	assert(ehdlr->state != EVENT_HANDLER_STATE_REMOVED);



	epevent.events = event_types;

	ehdlr->events = event_types;



	if (fgrp->parent) {

		epfd = fgrp->parent->epfd;

	} else {

		epfd = fgrp->epfd;

	}



	epevent.events = ehdlr->events;

	epevent.data.ptr = ehdlr;



	return epoll_ctl(fgrp->epfd, EPOLL_CTL_MOD, ehdlr->fd, &epevent);

	return epoll_ctl(epfd, EPOLL_CTL_MOD, ehdlr->fd, &epevent);

}



int
@@ -244,6 +420,17 @@ spdk_fd_group_wait(struct spdk_fd_group *fgrp, int timeout) 
	int n;

	int nfds;



	if (fgrp->parent != NULL) {

		if (timeout < 0) {

			SPDK_ERRLOG("Calling spdk_fd_group_wait on a group nested in another group without a timeout will block indefinitely.\n");

			assert(false);

			return -EINVAL;

		} else {

			SPDK_WARNLOG("Calling spdk_fd_group_wait on a group nested in another group will never find any events\n");

			return 0;

		}

	}



	nfds = epoll_wait(fgrp->epfd, events, totalfds, timeout);

	if (nfds < 0) {

		if (errno != EINTR) {
@@ -348,4 +535,16 @@ spdk_fd_group_wait(struct spdk_fd_group *fgrp, int timeout) 
	return -ENOTSUP;

}



int

spdk_fd_group_unnest(struct spdk_fd_group *parent, struct spdk_fd_group *child)

{

	return -ENOTSUP;

}



int

spdk_fd_group_nest(struct spdk_fd_group *parent, struct spdk_fd_group *child)

{

	return -ENOTSUP;

}



#endif

lib/util/spdk_util.map

+2 −0
Original line number Diff line number Diff line
@@ -165,6 +165,8 @@ 
	spdk_fd_group_remove;

	spdk_fd_group_event_modify;

	spdk_fd_group_get_fd;

	spdk_fd_group_nest;

	spdk_fd_group_unnest;



	# public functions in xor.h

	spdk_xor_gen;