numam-dpdk/lib/librte_vhost/vhost_user/fd_man.h
Huawei Xie dbfa62d63f vhost: support dynamically registering server
* support calling rte_vhost_driver_register after rte_vhost_driver_session_start
* add mutext to protect fdset from concurrent access
* add busy flag in fdentry. this flag is set before cb and cleared after cb is finished.

mutex lock scenario in vhost:

* event_dispatch(in rte_vhost_driver_session_start) runs in a separate thread, infinitely
processing vhost messages through cb(callback).
* event_dispatch acquires the lock, get the cb and its context, mark the busy flag,
and releases the mutex.
* vserver_new_vq_conn cb calls fdset_add, which acquires the mutex and add new fd into fdset.
* vserver_message_handler cb frees data context, marks remove flag to request to delete
connfd(connection fd) from fdset.
* after cb returns, event_dispatch
  1. clears busy flag.
  2. if there is remove request, call fdset_del, which acquires mutex, checks busy flag, and
removes connfd from fdset.
* rte_vhost_driver_unregister(not implemented) runs in another thread, acquires the mutex,
calls fdset_del to remove fd(listenerfd) from fdset. Then it could free data context.

The above steps ensures fd data context isn't freed when cb is using.

VM(s) should have been shutdown before rte_vhost_driver_unregister.

Signed-off-by: Huawei Xie <huawei.xie@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Tetsuya Mukawa <mukawa@igel.co.jp>
2015-02-24 01:38:17 +01:00

68 lines
2.4 KiB
C

/*-
* BSD LICENSE
*
* Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
* All rights reserved.
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* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
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* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Intel Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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*/
#ifndef _FD_MAN_H_
#define _FD_MAN_H_
#include <stdint.h>
#include <pthread.h>
#define MAX_FDS 1024
typedef void (*fd_cb)(int fd, void *dat, int *remove);
struct fdentry {
int fd; /* -1 indicates this entry is empty */
fd_cb rcb; /* callback when this fd is readable. */
fd_cb wcb; /* callback when this fd is writeable.*/
void *dat; /* fd context */
int busy; /* whether this entry is being used in cb. */
};
struct fdset {
struct fdentry fd[MAX_FDS];
pthread_mutex_t fd_mutex;
int num; /* current fd number of this fdset */
};
void fdset_init(struct fdset *pfdset);
int fdset_add(struct fdset *pfdset, int fd,
fd_cb rcb, fd_cb wcb, void *dat);
void fdset_del(struct fdset *pfdset, int fd);
void fdset_event_dispatch(struct fdset *pfdset);
#endif