diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-01-04 15:09:00 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-01-13 09:06:01 +0100 |
| commit | f96e9232e04856c781d4f71923a46dd3f7b429fa (patch) | |
| tree | 3c320a0a2bc03f54fea5c115b6c0fa1e4bcc7e27 /kernel/rcutree.c | |
| parent | 7284ce6c9f6153d1777df5f310c959724d1bd446 (diff) | |
| download | linux-f96e9232e04856c781d4f71923a46dd3f7b429fa.tar.bz2 | |
rcu: Adjust force_quiescent_state() locking, step 1
This causes rnp->lock to be held on entry to
force_quiescent_state()'s switch statement. This is a first
step towards prohibiting starting grace periods while
force_quiescent_state() is executing, which will reduce the
number and complexity of races that force_quiescent_state() is
involved in.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <12626465501455-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcutree.c')
| -rw-r--r-- | kernel/rcutree.c | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 53ae9598f798..eae331da6bee 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1204,7 +1204,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) } if (relaxed && (long)(rsp->jiffies_force_qs - jiffies) >= 0) - goto unlock_ret; /* no emergency and done recently. */ + goto unlock_fqs_ret; /* no emergency and done recently. */ rsp->n_force_qs++; spin_lock(&rnp->lock); lastcomp = rsp->gpnum - 1; @@ -1213,31 +1213,32 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) if(!rcu_gp_in_progress(rsp)) { rsp->n_force_qs_ngp++; spin_unlock(&rnp->lock); - goto unlock_ret; /* no GP in progress, time updated. */ + goto unlock_fqs_ret; /* no GP in progress, time updated. */ } - spin_unlock(&rnp->lock); switch (signaled) { case RCU_GP_IDLE: case RCU_GP_INIT: + spin_unlock(&rnp->lock); break; /* grace period idle or initializing, ignore. */ case RCU_SAVE_DYNTICK: + spin_unlock(&rnp->lock); if (RCU_SIGNAL_INIT != RCU_SAVE_DYNTICK) break; /* So gcc recognizes the dead code. */ /* Record dyntick-idle state. */ if (rcu_process_dyntick(rsp, lastcomp, dyntick_save_progress_counter)) - goto unlock_ret; + goto unlock_fqs_ret; + spin_lock(&rnp->lock); /* fall into next case. */ case RCU_SAVE_COMPLETED: /* Update state, record completion counter. */ forcenow = 0; - spin_lock(&rnp->lock); if (lastcomp + 1 == rsp->gpnum && lastcomp == rsp->completed && rsp->signaled == signaled) { @@ -1245,23 +1246,31 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) rsp->completed_fqs = lastcomp; forcenow = signaled == RCU_SAVE_COMPLETED; } - spin_unlock(&rnp->lock); - if (!forcenow) + if (!forcenow) { + spin_unlock(&rnp->lock); break; + } /* fall into next case. */ case RCU_FORCE_QS: /* Check dyntick-idle state, send IPI to laggarts. */ + spin_unlock(&rnp->lock); if (rcu_process_dyntick(rsp, rsp->completed_fqs, rcu_implicit_dynticks_qs)) - goto unlock_ret; + goto unlock_fqs_ret; /* Leave state in case more forcing is required. */ break; + + default: + + spin_unlock(&rnp->lock); + WARN_ON_ONCE(1); + break; } -unlock_ret: +unlock_fqs_ret: spin_unlock_irqrestore(&rsp->fqslock, flags); } |