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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-01-04 15:09:02 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-01-13 09:06:02 +0100 |
| commit | 07079d5357a4d53c2b13126c4a38fb40e6e04966 (patch) | |
| tree | 1a97552a220a9bbdfceb1cda01c1ee5b92ce75bd /kernel/rcutree.h | |
| parent | 559569acf94f538b56bd6eead80b439d6a78cdff (diff) | |
| download | linux-07079d5357a4d53c2b13126c4a38fb40e6e04966.tar.gz | |
rcu: Prohibit starting new grace periods while forcing quiescent states
Reduce the number and variety of race conditions by prohibiting the start of a new grace period while force_quiescent_state() is active. A new fqs_active flag in the rcu_state structure is used to trace whether or not force_quiescent_state() is active, and this new flag is tested by rcu_start_gp(). If the CPU that closed out the last grace period needs another grace period, this new grace period may be delayed up to one scheduling-clock tick, but it will eventually get started. 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: <126264655052-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcutree.h')
| -rw-r--r-- | kernel/rcutree.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h index d2a0046f63b2..dc386a7c634f 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -277,6 +277,8 @@ struct rcu_state { u8 signaled ____cacheline_internodealigned_in_smp; /* Force QS state. */ + u8 fqs_active; /* force_quiescent_state() */ + /* is running. */ long gpnum; /* Current gp number. */ long completed; /* # of last completed gp. */ |