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| author |   Byungchul Park <byungchul.park@lge.com> | 2016-11-09 17:57:13 +0900 |
|---|---|---|
| committer |   Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2017-01-23 11:32:22 -0800 |
| commit | c4402b27f1778fad0dbc27b2d88bb06ca22a06f0 (patch) | |
| tree | 5dbdefa7e7b390a9971246f0541673a563467d2a /kernel/rcu | |
| parent | Fix: Disable sys_membarrier when nohz_full is enabled (diff) | |
| download | linux-dev-c4402b27f1778fad0dbc27b2d88bb06ca22a06f0.tar.xz linux-dev-c4402b27f1778fad0dbc27b2d88bb06ca22a06f0.zip | |
rcu: Only dump stalled-tasks stacks if there was a real stall
The print_other_cpu_stall() function currently unconditionally invokes
rcu_print_detail_task_stall(). This is OK because if there was a stall
sufficient to cause print_other_cpu_stall() to be invoked, that stall
is very likely to persist through the entire print_other_cpu_stall()
execution. However, if the stall did not persist, the variable ndetected
will be zero, and that variable is already tested in an "if" statement.
Therefore, this commit moves the call to rcu_print_detail_task_stall()
under that pre-existing "if" to improve readability, with a very rare
reduction in overhead.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
[ paulmck: Reworked commit log. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index cb4e2056ccf3..6232d2f9a84e 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1379,6 +1379,9 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum) (long)rsp->gpnum, (long)rsp->completed, totqlen); if (ndetected) { rcu_dump_cpu_stacks(rsp); + + /* Complain about tasks blocking the grace period. */ + rcu_print_detail_task_stall(rsp); } else { if (READ_ONCE(rsp->gpnum) != gpnum || READ_ONCE(rsp->completed) == gpnum) { @@ -1395,9 +1398,6 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum) } } - /* Complain about tasks blocking the grace period. */ - rcu_print_detail_task_stall(rsp); - rcu_check_gp_kthread_starvation(rsp); panic_on_rcu_stall(); |