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  1. 18 7月, 2015 6 次提交
    • P
      rcu: Rework synchronize_sched_expedited() counter handling · d6ada2cf
      由 Paul E. McKenney 提交于 
      Now that synchronize_sched_expedited() have a mutex, it can use simpler
work-already-done detection scheme.  This commit simplifies this scheme
by using something similar to the sequence-locking counter scheme.
A counter is incremented before and after each grace period, so that
the counter is odd in the midst of the grace period and even otherwise.
So if the counter has advanced to the second even number that is
greater than or equal to the snapshot, the required grace period has
already happened.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      d6ada2cf
    • P
      rcu: Switch synchronize_sched_expedited() to stop_one_cpu() · c190c3b1
      由 Peter Zijlstra 提交于 
      The synchronize_sched_expedited() currently invokes try_stop_cpus(),
which schedules the stopper kthreads on each online non-idle CPU,
and waits until all those kthreads are running before letting any
of them stop.  This is disastrous for real-time workloads, which
get hit with a preemption that is as long as the longest scheduling
latency on any CPU, including any non-realtime housekeeping CPUs.
This commit therefore switches to using stop_one_cpu() on each CPU
in turn.  This avoids inflicting the worst-case scheduling latency
on the worst-case CPU onto all other CPUs, and also simplifies the
code a little bit.

Follow-up commits will simplify the counter-snapshotting algorithm
and convert a number of the counters that are now protected by the
new ->expedited_mutex to non-atomic.
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
[ paulmck: Kept stop_one_cpu(), dropped disabling of "guardrails". ]
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      c190c3b1
    • P
      rcu: Remove CONFIG_RCU_CPU_STALL_INFO · 75c27f11
      由 Paul E. McKenney 提交于 
      The CONFIG_RCU_CPU_STALL_INFO has been default-y for a couple of
releases with no complaints, so it is time to eliminate this Kconfig
option entirely, so that the long-form RCU CPU stall warnings cannot
be disabled.  This commit does just that.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      75c27f11
    • P
      rcu: Stop disabling CPU hotplug in synchronize_rcu_expedited() · 9b683874
      由 Paul E. McKenney 提交于 
      The fact that tasks could be migrated from leaf to root rcu_node
structures meant that synchronize_rcu_expedited() had to disable
CPU hotplug.  However, tasks now stay put, so this commit removes the
CPU-hotplug disabling from synchronize_rcu_expedited().
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      9b683874
    • P
      rcu: Reset rcu_fanout_leaf if out of bounds · 13bd6494
      由 Paul E. McKenney 提交于 
      Currently if the rcu_fanout_leaf boot parameter is out of bounds (that
is, less than RCU_FANOUT_LEAF or greater than the number of bits in an
unsigned long), a warning is issued and execution continues with the
out-of-bounds value.  This can result in all manner of failures, so this
patch resets rcu_fanout_leaf to RCU_FANOUT_LEAF when an out-of-bounds
condition is detected.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      13bd6494
    • A
      rcu: Shut up bogus gcc array bounds warning · 032dfc87
      由 Alexander Gordeev 提交于 
      Because gcc does not realize a loop would not be entered ever
(i.e. in case of rcu_num_lvls == 1):

  for (i = 1; i < rcu_num_lvls; i++)
	  rsp->level[i] = rsp->level[i - 1] + levelcnt[i - 1];

some compiler (pre- 5.x?) versions give a bogus warning:

  kernel/rcu/tree.c: In function ‘rcu_init_one.isra.55’:
  kernel/rcu/tree.c:4108:13: warning: array subscript is above array bounds [-Warray-bounds]
     rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1];
               ^
Fix that warning by adding an extra item to rcu_state::level[]
array. Once the bogus warning is fixed in gcc and kernel drops
support of older versions, the dummy item may be removed from
the array.

Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Suggested-by: N"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: NAlexander Gordeev <agordeev@redhat.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
      032dfc87
  3. 16 7月, 2015 10 次提交
  5. 04 7月, 2015 5 次提交
  7. 03 7月, 2015 1 次提交
  9. 01 7月, 2015 8 次提交
  11. 28 6月, 2015 2 次提交
  13. 27 6月, 2015 1 次提交
    • T
      timer: Fix hotplug regression · 24bfcb10
      由 Thomas Gleixner 提交于 
      The recent timer wheel rework removed the get/put_cpu_var() pair in
the hotplug migration code, which results in:

BUG: using smp_processor_id() in preemptible [00000000] code: hib.sh/2845
...
[<ffffffff810d4fa3>] timer_cpu_notify+0x53/0x12

That hunk is a leftover from an earlier iteration and went unnoticed
so far.

Restore the previous code which was obviously correct.

Fixes: 0eeda71b 'timer: Replace timer base by a cpu index'
Reported-and_tested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      24bfcb10
  15. 26 6月, 2015 7 次提交