[PATCH] per-task-delay-accounting: delay accounting usage of taskstats interface
Usage of taskstats interface by delay accounting. Signed-off-by: Shailabh Nagar <nagar@us.ibm.com> Signed-off-by: Balbir Singh <balbir@in.ibm.com> Cc: Jes Sorensen <jes@sgi.com> Cc: Peter Chubb <peterc@gelato.unsw.edu.au> Cc: Erich Focht <efocht@ess.nec.de> Cc: Levent Serinol <lserinol@gmail.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -18,6 +18,7 @@
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#define _LINUX_DELAYACCT_H
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#include <linux/sched.h>
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#include <linux/taskstats_kern.h>
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/*
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* Per-task flags relevant to delay accounting
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@ -35,6 +36,7 @@ extern void __delayacct_tsk_init(struct task_struct *);
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extern void __delayacct_tsk_exit(struct task_struct *);
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extern void __delayacct_blkio_start(void);
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extern void __delayacct_blkio_end(void);
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extern int __delayacct_add_tsk(struct taskstats *, struct task_struct *);
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static inline void delayacct_set_flag(int flag)
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{
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@ -74,6 +76,16 @@ static inline void delayacct_blkio_end(void)
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__delayacct_blkio_end();
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}
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static inline int delayacct_add_tsk(struct taskstats *d,
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struct task_struct *tsk)
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{
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if (likely(!delayacct_on))
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return -EINVAL;
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if (!tsk->delays)
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return 0;
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return __delayacct_add_tsk(d, tsk);
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}
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#else
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static inline void delayacct_set_flag(int flag)
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{}
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@ -89,6 +101,9 @@ static inline void delayacct_blkio_start(void)
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{}
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static inline void delayacct_blkio_end(void)
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{}
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static inline int delayacct_add_tsk(struct taskstats *d,
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struct task_struct *tsk)
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{ return 0; }
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#endif /* CONFIG_TASK_DELAY_ACCT */
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#endif
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@ -990,6 +990,7 @@ struct task_struct {
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*/
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struct pipe_inode_info *splice_pipe;
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#ifdef CONFIG_TASK_DELAY_ACCT
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spinlock_t delays_lock;
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struct task_delay_info *delays;
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#endif
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};
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@ -34,7 +34,60 @@
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struct taskstats {
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/* Version 1 */
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__u64 version;
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__u16 version;
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__u16 padding[3]; /* Userspace should not interpret the padding
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* field which can be replaced by useful
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* fields if struct taskstats is extended.
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*/
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/* Delay accounting fields start
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*
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* All values, until comment "Delay accounting fields end" are
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* available only if delay accounting is enabled, even though the last
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* few fields are not delays
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*
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* xxx_count is the number of delay values recorded
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* xxx_delay_total is the corresponding cumulative delay in nanoseconds
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*
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* xxx_delay_total wraps around to zero on overflow
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* xxx_count incremented regardless of overflow
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*/
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/* Delay waiting for cpu, while runnable
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* count, delay_total NOT updated atomically
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*/
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__u64 cpu_count;
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__u64 cpu_delay_total;
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/* Following four fields atomically updated using task->delays->lock */
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/* Delay waiting for synchronous block I/O to complete
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* does not account for delays in I/O submission
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*/
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__u64 blkio_count;
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__u64 blkio_delay_total;
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/* Delay waiting for page fault I/O (swap in only) */
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__u64 swapin_count;
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__u64 swapin_delay_total;
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/* cpu "wall-clock" running time
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* On some architectures, value will adjust for cpu time stolen
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* from the kernel in involuntary waits due to virtualization.
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* Value is cumulative, in nanoseconds, without a corresponding count
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* and wraps around to zero silently on overflow
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*/
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__u64 cpu_run_real_total;
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/* cpu "virtual" running time
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* Uses time intervals seen by the kernel i.e. no adjustment
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* for kernel's involuntary waits due to virtualization.
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* Value is cumulative, in nanoseconds, without a corresponding count
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* and wraps around to zero silently on overflow
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*/
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__u64 cpu_run_virtual_total;
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/* Delay accounting fields end */
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/* version 1 ends here */
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};
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@ -17,6 +17,7 @@ enum {
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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 void taskstats_exit_alloc(struct taskstats **ptidstats,
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struct taskstats **ptgidstats)
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@ -173,6 +173,7 @@ config TASKSTATS
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config TASK_DELAY_ACCT
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bool "Enable per-task delay accounting (EXPERIMENTAL)"
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depends on TASKSTATS
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help
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Collect information on time spent by a task waiting for system
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resources like cpu, synchronous block I/O completion and swapping
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@ -41,6 +41,10 @@ void delayacct_init(void)
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void __delayacct_tsk_init(struct task_struct *tsk)
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{
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spin_lock_init(&tsk->delays_lock);
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/* No need to acquire tsk->delays_lock for allocation here unless
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__delayacct_tsk_init called after tsk is attached to tasklist
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*/
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tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL);
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if (tsk->delays)
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spin_lock_init(&tsk->delays->lock);
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@ -48,8 +52,11 @@ void __delayacct_tsk_init(struct task_struct *tsk)
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void __delayacct_tsk_exit(struct task_struct *tsk)
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{
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kmem_cache_free(delayacct_cache, tsk->delays);
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struct task_delay_info *delays = tsk->delays;
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spin_lock(&tsk->delays_lock);
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tsk->delays = NULL;
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spin_unlock(&tsk->delays_lock);
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kmem_cache_free(delayacct_cache, delays);
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}
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/*
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@ -104,3 +111,56 @@ void __delayacct_blkio_end(void)
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¤t->delays->blkio_delay,
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¤t->delays->blkio_count);
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}
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int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
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{
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s64 tmp;
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struct timespec ts;
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unsigned long t1,t2,t3;
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spin_lock(&tsk->delays_lock);
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/* Though tsk->delays accessed later, early exit avoids
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* unnecessary returning of other data
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*/
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if (!tsk->delays)
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goto done;
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tmp = (s64)d->cpu_run_real_total;
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cputime_to_timespec(tsk->utime + tsk->stime, &ts);
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tmp += timespec_to_ns(&ts);
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d->cpu_run_real_total = (tmp < (s64)d->cpu_run_real_total) ? 0 : tmp;
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/*
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* No locking available for sched_info (and too expensive to add one)
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* Mitigate by taking snapshot of values
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*/
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t1 = tsk->sched_info.pcnt;
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t2 = tsk->sched_info.run_delay;
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t3 = tsk->sched_info.cpu_time;
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d->cpu_count += t1;
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jiffies_to_timespec(t2, &ts);
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tmp = (s64)d->cpu_delay_total + timespec_to_ns(&ts);
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d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;
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tmp = (s64)d->cpu_run_virtual_total + (s64)jiffies_to_usecs(t3) * 1000;
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d->cpu_run_virtual_total =
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(tmp < (s64)d->cpu_run_virtual_total) ? 0 : tmp;
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/* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */
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spin_lock(&tsk->delays->lock);
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tmp = d->blkio_delay_total + tsk->delays->blkio_delay;
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d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;
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tmp = d->swapin_delay_total + tsk->delays->swapin_delay;
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d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;
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d->blkio_count += tsk->delays->blkio_count;
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d->swapin_count += tsk->delays->swapin_count;
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spin_unlock(&tsk->delays->lock);
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done:
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spin_unlock(&tsk->delays_lock);
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return 0;
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}
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@ -18,13 +18,13 @@
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#include <linux/kernel.h>
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#include <linux/taskstats_kern.h>
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#include <linux/delayacct.h>
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#include <net/genetlink.h>
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#include <asm/atomic.h>
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static DEFINE_PER_CPU(__u32, taskstats_seqnum) = { 0 };
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static int family_registered;
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kmem_cache_t *taskstats_cache;
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static DEFINE_MUTEX(taskstats_exit_mutex);
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static struct genl_family family = {
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.id = GENL_ID_GENERATE,
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* goto err;
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*/
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err:
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rc = delayacct_add_tsk(stats, tsk);
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stats->version = TASKSTATS_VERSION;
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/* Define err: label here if needed */
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put_task_struct(tsk);
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return rc;
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* break;
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*/
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rc = delayacct_add_tsk(stats, tsk);
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if (rc)
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break;
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} while_each_thread(first, tsk);
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read_unlock(&tasklist_lock);
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stats->version = TASKSTATS_VERSION;
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/*
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* Accounting subsytems can also add calls here if they don't
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if (!family_registered || !tidstats)
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return;
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mutex_lock(&taskstats_exit_mutex);
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is_thread_group = !thread_group_empty(tsk);
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rc = 0;
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err_skb:
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nlmsg_free(rep_skb);
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ret:
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mutex_unlock(&taskstats_exit_mutex);
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return;
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}
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