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author | Ingo Molnar <mingo@elte.hu> | 2009-11-10 04:10:31 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-11-10 04:10:35 +0100 |
commit | 7e1a2766e67a529f62c8cfba0a47d63fc4f7fa8a (patch) | |
tree | 197950369a773afdf04af9bdfc4a2ce1d2b5d3af | |
parent | c5e0cb3ddc5f14cedcfc50c0fb3b5fc6b56576da (diff) | |
parent | 83f5b01ffbbaea6f97c9a79d21e240dbfb69f2f1 (diff) | |
download | linux-7e1a2766e67a529f62c8cfba0a47d63fc4f7fa8a.tar.gz linux-7e1a2766e67a529f62c8cfba0a47d63fc4f7fa8a.tar.bz2 linux-7e1a2766e67a529f62c8cfba0a47d63fc4f7fa8a.zip |
Merge branch 'core/urgent' into core/rcu
Merge reason: Pick up RCU fixlet to base further commits on.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r-- | kernel/futex.c | 9 | ||||
-rw-r--r-- | kernel/rcutree.c | 31 | ||||
-rw-r--r-- | kernel/rcutree.h | 13 | ||||
-rw-r--r-- | kernel/rcutree_plugin.h | 25 | ||||
-rw-r--r-- | kernel/user.c | 2 |
5 files changed, 53 insertions, 27 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index 06938e560ac9..fb65e822fc41 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1029,7 +1029,6 @@ static inline void requeue_pi_wake_futex(struct futex_q *q, union futex_key *key, struct futex_hash_bucket *hb) { - drop_futex_key_refs(&q->key); get_futex_key_refs(key); q->key = *key; @@ -1227,6 +1226,7 @@ retry_private: */ if (ret == 1) { WARN_ON(pi_state); + drop_count++; task_count++; ret = get_futex_value_locked(&curval2, uaddr2); if (!ret) @@ -1305,6 +1305,7 @@ retry_private: if (ret == 1) { /* We got the lock. */ requeue_pi_wake_futex(this, &key2, hb2); + drop_count++; continue; } else if (ret) { /* -EDEADLK */ @@ -2126,7 +2127,7 @@ int handle_early_requeue_pi_wakeup(struct futex_hash_bucket *hb, plist_del(&q->list, &q->list.plist); /* Handle spurious wakeups gracefully */ - ret = -EAGAIN; + ret = -EWOULDBLOCK; if (timeout && !timeout->task) ret = -ETIMEDOUT; else if (signal_pending(current)) @@ -2207,7 +2208,6 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, int fshared, debug_rt_mutex_init_waiter(&rt_waiter); rt_waiter.task = NULL; -retry: key2 = FUTEX_KEY_INIT; ret = get_futex_key(uaddr2, fshared, &key2, VERIFY_WRITE); if (unlikely(ret != 0)) @@ -2302,9 +2302,6 @@ out_put_keys: out_key2: put_futex_key(fshared, &key2); - /* Spurious wakeup ? */ - if (ret == -EAGAIN) - goto retry; out: if (to) { hrtimer_cancel(&to->timer); diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 055f1a941a9e..69f4efec3449 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -61,7 +61,7 @@ static struct lock_class_key rcu_root_class; NUM_RCU_LVL_2, \ NUM_RCU_LVL_3, /* == MAX_RCU_LVLS */ \ }, \ - .signaled = RCU_SIGNAL_INIT, \ + .signaled = RCU_GP_IDLE, \ .gpnum = -300, \ .completed = -300, \ .onofflock = __SPIN_LOCK_UNLOCKED(&name.onofflock), \ @@ -659,14 +659,17 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) * irqs disabled. */ rcu_for_each_node_breadth_first(rsp, rnp) { - spin_lock(&rnp->lock); /* irqs already disabled. */ + spin_lock(&rnp->lock); /* irqs already disabled. */ rcu_preempt_check_blocked_tasks(rnp); rnp->qsmask = rnp->qsmaskinit; rnp->gpnum = rsp->gpnum; - spin_unlock(&rnp->lock); /* irqs already disabled. */ + spin_unlock(&rnp->lock); /* irqs remain disabled. */ } + rnp = rcu_get_root(rsp); + spin_lock(&rnp->lock); /* irqs already disabled. */ rsp->signaled = RCU_SIGNAL_INIT; /* force_quiescent_state now OK. */ + spin_unlock(&rnp->lock); /* irqs remain disabled. */ spin_unlock_irqrestore(&rsp->onofflock, flags); } @@ -708,6 +711,7 @@ static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags) { WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); rsp->completed = rsp->gpnum; + rsp->signaled = RCU_GP_IDLE; rcu_process_gp_end(rsp, rsp->rda[smp_processor_id()]); rcu_start_gp(rsp, flags); /* releases root node's rnp->lock. */ } @@ -915,7 +919,20 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp) spin_unlock(&rnp->lock); /* irqs remain disabled. */ break; } - rcu_preempt_offline_tasks(rsp, rnp, rdp); + + /* + * If there was a task blocking the current grace period, + * and if all CPUs have checked in, we need to propagate + * the quiescent state up the rcu_node hierarchy. But that + * is inconvenient at the moment due to deadlock issues if + * this should end the current grace period. So set the + * offlined CPU's bit in ->qsmask in order to force the + * next force_quiescent_state() invocation to clean up this + * mess in a deadlock-free manner. + */ + if (rcu_preempt_offline_tasks(rsp, rnp, rdp) && !rnp->qsmask) + rnp->qsmask |= mask; + mask = rnp->grpmask; spin_unlock(&rnp->lock); /* irqs remain disabled. */ rnp = rnp->parent; @@ -1151,9 +1168,10 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) } spin_unlock(&rnp->lock); switch (signaled) { + case RCU_GP_IDLE: case RCU_GP_INIT: - break; /* grace period still initializing, ignore. */ + break; /* grace period idle or initializing, ignore. */ case RCU_SAVE_DYNTICK: @@ -1167,7 +1185,8 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) /* Update state, record completion counter. */ spin_lock(&rnp->lock); - if (lastcomp == rsp->completed) { + if (lastcomp == rsp->completed && + rsp->signaled == RCU_SAVE_DYNTICK) { rsp->signaled = RCU_FORCE_QS; dyntick_record_completed(rsp, lastcomp); } diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 599161f309fb..1899023b0962 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -201,9 +201,10 @@ struct rcu_data { }; /* Values for signaled field in struct rcu_state. */ -#define RCU_GP_INIT 0 /* Grace period being initialized. */ -#define RCU_SAVE_DYNTICK 1 /* Need to scan dyntick state. */ -#define RCU_FORCE_QS 2 /* Need to force quiescent state. */ +#define RCU_GP_IDLE 0 /* No grace period in progress. */ +#define RCU_GP_INIT 1 /* Grace period being initialized. */ +#define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */ +#define RCU_FORCE_QS 3 /* Need to force quiescent state. */ #ifdef CONFIG_NO_HZ #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK #else /* #ifdef CONFIG_NO_HZ */ @@ -306,9 +307,9 @@ static void rcu_print_task_stall(struct rcu_node *rnp); #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); #ifdef CONFIG_HOTPLUG_CPU -static void rcu_preempt_offline_tasks(struct rcu_state *rsp, - struct rcu_node *rnp, - struct rcu_data *rdp); +static int rcu_preempt_offline_tasks(struct rcu_state *rsp, + struct rcu_node *rnp, + struct rcu_data *rdp); static void rcu_preempt_offline_cpu(int cpu); #endif /* #ifdef CONFIG_HOTPLUG_CPU */ static void rcu_preempt_check_callbacks(int cpu); diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index ebd20ee7707d..ef2a58c2b9d5 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -304,21 +304,25 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) * parent is to remove the need for rcu_read_unlock_special() to * make more than two attempts to acquire the target rcu_node's lock. * + * Returns 1 if there was previously a task blocking the current grace + * period on the specified rcu_node structure. + * * The caller must hold rnp->lock with irqs disabled. */ -static void rcu_preempt_offline_tasks(struct rcu_state *rsp, - struct rcu_node *rnp, - struct rcu_data *rdp) +static int rcu_preempt_offline_tasks(struct rcu_state *rsp, + struct rcu_node *rnp, + struct rcu_data *rdp) { int i; struct list_head *lp; struct list_head *lp_root; + int retval = rcu_preempted_readers(rnp); struct rcu_node *rnp_root = rcu_get_root(rsp); struct task_struct *tp; if (rnp == rnp_root) { WARN_ONCE(1, "Last CPU thought to be offlined?"); - return; /* Shouldn't happen: at least one CPU online. */ + return 0; /* Shouldn't happen: at least one CPU online. */ } WARN_ON_ONCE(rnp != rdp->mynode && (!list_empty(&rnp->blocked_tasks[0]) || @@ -342,6 +346,8 @@ static void rcu_preempt_offline_tasks(struct rcu_state *rsp, spin_unlock(&rnp_root->lock); /* irqs remain disabled */ } } + + return retval; } /* @@ -532,12 +538,15 @@ static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp) /* * Because preemptable RCU does not exist, it never needs to migrate - * tasks that were blocked within RCU read-side critical sections. + * tasks that were blocked within RCU read-side critical sections, and + * such non-existent tasks cannot possibly have been blocking the current + * grace period. */ -static void rcu_preempt_offline_tasks(struct rcu_state *rsp, - struct rcu_node *rnp, - struct rcu_data *rdp) +static int rcu_preempt_offline_tasks(struct rcu_state *rsp, + struct rcu_node *rnp, + struct rcu_data *rdp) { + return 0; } /* diff --git a/kernel/user.c b/kernel/user.c index 2c000e7132ac..46d0165ca70c 100644 --- a/kernel/user.c +++ b/kernel/user.c @@ -330,9 +330,9 @@ done: */ static void free_user(struct user_struct *up, unsigned long flags) { - spin_unlock_irqrestore(&uidhash_lock, flags); INIT_DELAYED_WORK(&up->work, cleanup_user_struct); schedule_delayed_work(&up->work, msecs_to_jiffies(1000)); + spin_unlock_irqrestore(&uidhash_lock, flags); } #else /* CONFIG_USER_SCHED && CONFIG_SYSFS */ |