c8924363da
Don't send taskstats (per-pid or per-tgid) on thread exit when no one is listening for such data. Currently the taskstats interface allocates a structure, fills it in and calls netlink to send out per-pid and per-tgid stats regardless of whether a userspace listener for the data exists (netlink layer would check for that and avoid the multicast). As a result of this patch, the check for the no-listener case is performed early, avoiding the redundant allocation and filling up of the taskstats structures. Signed-off-by: Balbir Singh <balbir@in.ibm.com> Signed-off-by: Shailabh Nagar <nagar@watson.ibm.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
108 lines
2.6 KiB
C
108 lines
2.6 KiB
C
/* taskstats_kern.h - kernel header for per-task statistics interface
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*
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* Copyright (C) Shailabh Nagar, IBM Corp. 2006
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* (C) Balbir Singh, IBM Corp. 2006
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*/
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#ifndef _LINUX_TASKSTATS_KERN_H
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#define _LINUX_TASKSTATS_KERN_H
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#include <linux/taskstats.h>
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#include <linux/sched.h>
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#include <net/genetlink.h>
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enum {
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TASKSTATS_MSG_UNICAST, /* send data only to requester */
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TASKSTATS_MSG_MULTICAST, /* send data to a group */
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};
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#ifdef CONFIG_TASKSTATS
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extern kmem_cache_t *taskstats_cache;
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extern struct mutex taskstats_exit_mutex;
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static inline int taskstats_has_listeners(void)
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{
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if (!genl_sock)
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return 0;
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return netlink_has_listeners(genl_sock, TASKSTATS_LISTEN_GROUP);
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}
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static inline void taskstats_exit_alloc(struct taskstats **ptidstats)
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{
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*ptidstats = NULL;
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if (taskstats_has_listeners())
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*ptidstats = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
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}
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static inline void taskstats_exit_free(struct taskstats *tidstats)
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{
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if (tidstats)
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kmem_cache_free(taskstats_cache, tidstats);
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}
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static inline void taskstats_tgid_init(struct signal_struct *sig)
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{
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spin_lock_init(&sig->stats_lock);
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sig->stats = NULL;
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}
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static inline void taskstats_tgid_alloc(struct signal_struct *sig)
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{
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struct taskstats *stats;
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unsigned long flags;
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stats = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
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if (!stats)
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return;
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spin_lock_irqsave(&sig->stats_lock, flags);
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if (!sig->stats) {
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sig->stats = stats;
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stats = NULL;
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}
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spin_unlock_irqrestore(&sig->stats_lock, flags);
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if (stats)
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kmem_cache_free(taskstats_cache, stats);
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}
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static inline void taskstats_tgid_free(struct signal_struct *sig)
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{
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struct taskstats *stats = NULL;
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unsigned long flags;
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spin_lock_irqsave(&sig->stats_lock, flags);
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if (sig->stats) {
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stats = sig->stats;
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sig->stats = NULL;
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}
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spin_unlock_irqrestore(&sig->stats_lock, flags);
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if (stats)
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kmem_cache_free(taskstats_cache, stats);
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}
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extern void taskstats_exit_send(struct task_struct *, struct taskstats *, int);
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extern void taskstats_init_early(void);
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extern void taskstats_tgid_alloc(struct signal_struct *);
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#else
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static inline void taskstats_exit_alloc(struct taskstats **ptidstats)
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{}
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static inline void taskstats_exit_free(struct taskstats *ptidstats)
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{}
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static inline void taskstats_exit_send(struct task_struct *tsk,
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struct taskstats *tidstats,
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int group_dead)
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{}
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static inline void taskstats_tgid_init(struct signal_struct *sig)
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{}
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static inline void taskstats_tgid_alloc(struct signal_struct *sig)
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{}
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static inline void taskstats_tgid_free(struct signal_struct *sig)
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{}
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static inline void taskstats_init_early(void)
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{}
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#endif /* CONFIG_TASKSTATS */
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#endif
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