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| author | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-06-22 14:35:59 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.ibm.com> | 2019-08-01 14:30:22 -0700 |
| commit | bd1bfc51a36f334270b886db6d8467e55fe294ca (patch) | |
| tree | 5c27c53514cc90778142b15aa53d07fbb05787b1 | |
| parent | f4e8352928587ef8772df3d269a328efa609daaa (diff) | |
| download | linux-bd1bfc51a36f334270b886db6d8467e55fe294ca.tar.gz linux-bd1bfc51a36f334270b886db6d8467e55fe294ca.tar.bz2 linux-bd1bfc51a36f334270b886db6d8467e55fe294ca.zip | |
rcutorture: Emulate userspace sojourn during call_rcu() floods
During an actual call_rcu() flood, there would be frequent trips to
userspace (in-kernel call_rcu() floods must be otherwise housebroken).
Userspace execution allows a great many things to interrupt execution,
and rcutorture needs to also allow such interruptions. This commit
therefore causes call_rcu() floods to occasionally invoke schedule(),
thus preventing spurious rcutorture failures due to other parts of the
kernel becoming irate at the call_rcu() flood events.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
| -rw-r--r-- | kernel/rcu/rcutorture.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index fce4e7e6f502..c44e5307afcc 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1713,12 +1713,14 @@ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp) } // Give the scheduler a chance, even on nohz_full CPUs. -static void rcu_torture_fwd_prog_cond_resched(void) +static void rcu_torture_fwd_prog_cond_resched(unsigned long iter) { if (IS_ENABLED(CONFIG_PREEMPT) && IS_ENABLED(CONFIG_NO_HZ_FULL)) { - if (need_resched()) + // Real call_rcu() floods hit userspace, so emulate that. + if (need_resched() || (iter & 0xfff)) schedule(); } else { + // No userspace emulation: CB invocation throttles call_rcu() cond_resched(); } } @@ -1746,7 +1748,7 @@ static unsigned long rcu_torture_fwd_prog_cbfree(void) spin_unlock_irqrestore(&rcu_fwd_lock, flags); kfree(rfcp); freed++; - rcu_torture_fwd_prog_cond_resched(); + rcu_torture_fwd_prog_cond_resched(freed); } return freed; } @@ -1790,7 +1792,7 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries) udelay(10); cur_ops->readunlock(idx); if (!fwd_progress_need_resched || need_resched()) - rcu_torture_fwd_prog_cond_resched(); + rcu_torture_fwd_prog_cond_resched(1); } (*tested_tries)++; if (!time_before(jiffies, stopat) && @@ -1875,7 +1877,7 @@ static void rcu_torture_fwd_prog_cr(void) rfcp->rfc_gps = 0; } cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr); - rcu_torture_fwd_prog_cond_resched(); + rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs); } stoppedat = jiffies; n_launders_cb_snap = READ_ONCE(n_launders_cb); |