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Diffstat (limited to 'Documentation/RCU/Design/Requirements')
| -rw-r--r-- | Documentation/RCU/Design/Requirements/Requirements.rst | 33 |
1 files changed, 17 insertions, 16 deletions
diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst index f24b3c0b9b0d..ba417a08b93d 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.rst +++ b/Documentation/RCU/Design/Requirements/Requirements.rst @@ -2637,15 +2637,16 @@ synchronize_srcu() for some other domain ``ss1``, and if an that was held across as ``ss``-domain synchronize_srcu(), deadlock would again be possible. Such a deadlock cycle could extend across an arbitrarily large number of different SRCU domains. Again, with great -power comes great responsibility. +power comes great responsibility, though lockdep is now able to detect +this sort of deadlock. -Unlike the other RCU flavors, SRCU read-side critical sections can run -on idle and even offline CPUs. This ability requires that -srcu_read_lock() and srcu_read_unlock() contain memory barriers, -which means that SRCU readers will run a bit slower than would RCU -readers. It also motivates the smp_mb__after_srcu_read_unlock() API, -which, in combination with srcu_read_unlock(), guarantees a full -memory barrier. +Unlike the other RCU flavors, SRCU read-side critical sections can run on +idle and even offline CPUs, with the exception of srcu_read_lock_fast() +and friends. This ability requires that srcu_read_lock() and +srcu_read_unlock() contain memory barriers, which means that SRCU +readers will run a bit slower than would RCU readers. It also motivates +the smp_mb__after_srcu_read_unlock() API, which, in combination with +srcu_read_unlock(), guarantees a full memory barrier. Also unlike other RCU flavors, synchronize_srcu() may **not** be invoked from CPU-hotplug notifiers, due to the fact that SRCU grace @@ -2681,15 +2682,15 @@ run some tests first. SRCU just might need a few adjustment to deal with that sort of load. Of course, your mileage may vary based on the speed of your CPUs and the size of your memory. -The `SRCU -API <https://lwn.net/Articles/609973/#RCU%20Per-Flavor%20API%20Table>`__ +The `SRCU API +<https://lwn.net/Articles/609973/#RCU%20Per-Flavor%20API%20Table>`__ includes srcu_read_lock(), srcu_read_unlock(), -srcu_dereference(), srcu_dereference_check(), -synchronize_srcu(), synchronize_srcu_expedited(), -call_srcu(), srcu_barrier(), and srcu_read_lock_held(). It -also includes DEFINE_SRCU(), DEFINE_STATIC_SRCU(), and -init_srcu_struct() APIs for defining and initializing -``srcu_struct`` structures. +srcu_dereference(), srcu_dereference_check(), synchronize_srcu(), +synchronize_srcu_expedited(), call_srcu(), srcu_barrier(), +and srcu_read_lock_held(). It also includes DEFINE_SRCU(), +DEFINE_STATIC_SRCU(), DEFINE_SRCU_FAST(), DEFINE_STATIC_SRCU_FAST(), +init_srcu_struct(), and init_srcu_struct_fast() APIs for defining and +initializing ``srcu_struct`` structures. More recently, the SRCU API has added polling interfaces: |