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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-08-09 03:27:52 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2013-09-23 18:16:10 +0200 |
| commit | f7be82093952ee4a74ffc8c729b2811f908cd9a4 (patch) | |
| tree | 7462d2551c370edcf614e36cdefd008e2689b529 /kernel/rcutree.c | |
| parent | Linux 3.12-rc1 (diff) | |
| download | linux-f7be82093952ee4a74ffc8c729b2811f908cd9a4.tar.xz linux-f7be82093952ee4a74ffc8c729b2811f908cd9a4.zip | |
rcu: Improve grace-period start logic
This commit improves grace-period start logic by checking ->gp_flags
under the lock and by issuing a warning if a grace period is already
in progress.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.c')
| -rw-r--r-- | kernel/rcutree.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 32618b3fe4e6..d679a522c0a2 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1297,7 +1297,7 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp) } /* - * Initialize a new grace period. + * Initialize a new grace period. Return 0 if no grace period required. */ static int rcu_gp_init(struct rcu_state *rsp) { @@ -1306,10 +1306,18 @@ static int rcu_gp_init(struct rcu_state *rsp) rcu_bind_gp_kthread(); raw_spin_lock_irq(&rnp->lock); + if (rsp->gp_flags == 0) { + /* Spurious wakeup, tell caller to go back to sleep. */ + raw_spin_unlock_irq(&rnp->lock); + return 0; + } rsp->gp_flags = 0; /* Clear all flags: New grace period. */ - if (rcu_gp_in_progress(rsp)) { - /* Grace period already in progress, don't start another. */ + if (WARN_ON_ONCE(rcu_gp_in_progress(rsp))) { + /* + * Grace period already in progress, don't start another. + * Not supposed to be able to happen. + */ raw_spin_unlock_irq(&rnp->lock); return 0; } @@ -1474,8 +1482,7 @@ static int __noreturn rcu_gp_kthread(void *arg) wait_event_interruptible(rsp->gp_wq, rsp->gp_flags & RCU_GP_FLAG_INIT); - if ((rsp->gp_flags & RCU_GP_FLAG_INIT) && - rcu_gp_init(rsp)) + if (rcu_gp_init(rsp)) break; cond_resched(); flush_signals(current); |