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![Jeff Mahoney](/assets/img/avatar_default.png)
The taskstats structure is internally aligned on 8 byte boundaries but the
layout of the aggregrate reply, with two NLA headers and the pid (each 4
bytes), actually force the entire structure to be unaligned. This causes
the kernel to issue unaligned access warnings on some architectures like
ia64. Unfortunately, some software out there doesn't properly unroll the
NLA packet and assumes that the start of the taskstats structure will
always be 20 bytes from the start of the netlink payload. Aligning the
start of the taskstats structure breaks this software, which we don't
want. So, for now the alignment only happens on architectures that
require it and those users will have to update to fixed versions of those
packages. Space is reserved in the packet only when needed. This ifdef
should be removed in several years e.g. 2012 once we can be confident
that fixed versions are installed on most systems. We add the padding
before the aggregate since the aggregate is already a defined type.
Commit 85893120
("delayacct: align to 8 byte boundary on 64-bit systems")
previously addressed the alignment issues by padding out the pid field.
This was supposed to be a compatible change but the circumstances
described above mean that it wasn't. This patch backs out that change,
since it was a hack, and introduces a new NULL attribute type to provide
the padding. Padding the response with 4 bytes avoids allocating an
aligned taskstats structure and copying it back. Since the structure
weighs in at 328 bytes, it's too big to do it on the stack.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reported-by: Brian Rogers <brian@xyzw.org>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: Guillaume Chazarain <guichaz@gmail.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
213 lines
6.8 KiB
C
213 lines
6.8 KiB
C
/* taskstats.h - exporting per-task statistics
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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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* (C) Jay Lan, SGI, 2006
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of version 2.1 of the GNU Lesser General Public License
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#ifndef _LINUX_TASKSTATS_H
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#define _LINUX_TASKSTATS_H
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#include <linux/types.h>
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/* Format for per-task data returned to userland when
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* - a task exits
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* - listener requests stats for a task
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*
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* The struct is versioned. Newer versions should only add fields to
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* the bottom of the struct to maintain backward compatibility.
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*
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*
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* To add new fields
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* a) bump up TASKSTATS_VERSION
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* b) add comment indicating new version number at end of struct
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* c) add new fields after version comment; maintain 64-bit alignment
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*/
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#define TASKSTATS_VERSION 8
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#define TS_COMM_LEN 32 /* should be >= TASK_COMM_LEN
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* in linux/sched.h */
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struct taskstats {
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/* The version number of this struct. This field is always set to
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* TAKSTATS_VERSION, which is defined in <linux/taskstats.h>.
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* Each time the struct is changed, the value should be incremented.
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*/
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__u16 version;
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__u32 ac_exitcode; /* Exit status */
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/* The accounting flags of a task as defined in <linux/acct.h>
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* Defined values are AFORK, ASU, ACOMPAT, ACORE, and AXSIG.
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*/
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__u8 ac_flag; /* Record flags */
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__u8 ac_nice; /* task_nice */
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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 __attribute__((aligned(8)));
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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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/* Basic Accounting Fields start */
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char ac_comm[TS_COMM_LEN]; /* Command name */
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__u8 ac_sched __attribute__((aligned(8)));
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/* Scheduling discipline */
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__u8 ac_pad[3];
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__u32 ac_uid __attribute__((aligned(8)));
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/* User ID */
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__u32 ac_gid; /* Group ID */
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__u32 ac_pid; /* Process ID */
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__u32 ac_ppid; /* Parent process ID */
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__u32 ac_btime; /* Begin time [sec since 1970] */
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__u64 ac_etime __attribute__((aligned(8)));
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/* Elapsed time [usec] */
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__u64 ac_utime; /* User CPU time [usec] */
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__u64 ac_stime; /* SYstem CPU time [usec] */
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__u64 ac_minflt; /* Minor Page Fault Count */
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__u64 ac_majflt; /* Major Page Fault Count */
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/* Basic Accounting Fields end */
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/* Extended accounting fields start */
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/* Accumulated RSS usage in duration of a task, in MBytes-usecs.
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* The current rss usage is added to this counter every time
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* a tick is charged to a task's system time. So, at the end we
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* will have memory usage multiplied by system time. Thus an
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* average usage per system time unit can be calculated.
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*/
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__u64 coremem; /* accumulated RSS usage in MB-usec */
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/* Accumulated virtual memory usage in duration of a task.
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* Same as acct_rss_mem1 above except that we keep track of VM usage.
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*/
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__u64 virtmem; /* accumulated VM usage in MB-usec */
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/* High watermark of RSS and virtual memory usage in duration of
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* a task, in KBytes.
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*/
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__u64 hiwater_rss; /* High-watermark of RSS usage, in KB */
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__u64 hiwater_vm; /* High-water VM usage, in KB */
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/* The following four fields are I/O statistics of a task. */
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__u64 read_char; /* bytes read */
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__u64 write_char; /* bytes written */
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__u64 read_syscalls; /* read syscalls */
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__u64 write_syscalls; /* write syscalls */
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/* Extended accounting fields end */
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#define TASKSTATS_HAS_IO_ACCOUNTING
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/* Per-task storage I/O accounting starts */
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__u64 read_bytes; /* bytes of read I/O */
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__u64 write_bytes; /* bytes of write I/O */
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__u64 cancelled_write_bytes; /* bytes of cancelled write I/O */
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__u64 nvcsw; /* voluntary_ctxt_switches */
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__u64 nivcsw; /* nonvoluntary_ctxt_switches */
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/* time accounting for SMT machines */
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__u64 ac_utimescaled; /* utime scaled on frequency etc */
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__u64 ac_stimescaled; /* stime scaled on frequency etc */
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__u64 cpu_scaled_run_real_total; /* scaled cpu_run_real_total */
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/* Delay waiting for memory reclaim */
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__u64 freepages_count;
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__u64 freepages_delay_total;
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};
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/*
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* Commands sent from userspace
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* Not versioned. New commands should only be inserted at the enum's end
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* prior to __TASKSTATS_CMD_MAX
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*/
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enum {
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TASKSTATS_CMD_UNSPEC = 0, /* Reserved */
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TASKSTATS_CMD_GET, /* user->kernel request/get-response */
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TASKSTATS_CMD_NEW, /* kernel->user event */
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__TASKSTATS_CMD_MAX,
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};
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#define TASKSTATS_CMD_MAX (__TASKSTATS_CMD_MAX - 1)
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enum {
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TASKSTATS_TYPE_UNSPEC = 0, /* Reserved */
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TASKSTATS_TYPE_PID, /* Process id */
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TASKSTATS_TYPE_TGID, /* Thread group id */
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TASKSTATS_TYPE_STATS, /* taskstats structure */
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TASKSTATS_TYPE_AGGR_PID, /* contains pid + stats */
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TASKSTATS_TYPE_AGGR_TGID, /* contains tgid + stats */
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TASKSTATS_TYPE_NULL, /* contains nothing */
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__TASKSTATS_TYPE_MAX,
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};
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#define TASKSTATS_TYPE_MAX (__TASKSTATS_TYPE_MAX - 1)
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enum {
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TASKSTATS_CMD_ATTR_UNSPEC = 0,
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TASKSTATS_CMD_ATTR_PID,
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TASKSTATS_CMD_ATTR_TGID,
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TASKSTATS_CMD_ATTR_REGISTER_CPUMASK,
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TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK,
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__TASKSTATS_CMD_ATTR_MAX,
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};
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#define TASKSTATS_CMD_ATTR_MAX (__TASKSTATS_CMD_ATTR_MAX - 1)
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/* NETLINK_GENERIC related info */
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#define TASKSTATS_GENL_NAME "TASKSTATS"
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#define TASKSTATS_GENL_VERSION 0x1
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#endif /* _LINUX_TASKSTATS_H */
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