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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2013-03-12 16:54:14 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2013-06-10 13:45:25 -0700
commit99f88919f8fa8a8b01b5306c59c9977b94604df8 (patch)
tree8e92937651258199944fed1ae2b612f0f693be00 /Documentation/RCU
parentefc151c33b971148894789dc7c5589dec46d4348 (diff)
rcu: Remove srcu_read_lock_raw() and srcu_read_unlock_raw().
These interfaces never did get used, so this commit removes them, their rcutorture tests, and documentation referencing them. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'Documentation/RCU')
-rw-r--r--Documentation/RCU/checklist.txt6
-rw-r--r--Documentation/RCU/torture.txt6
-rw-r--r--Documentation/RCU/whatisRCU.txt22
3 files changed, 7 insertions, 27 deletions
diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index 79e789b8b8ea..7703ec73a9bb 100644
--- a/Documentation/RCU/checklist.txt
+++ b/Documentation/RCU/checklist.txt
@@ -354,12 +354,6 @@ over a rather long period of time, but improvements are always welcome!
using RCU rather than SRCU, because RCU is almost always faster
and easier to use than is SRCU.
- If you need to enter your read-side critical section in a
- hardirq or exception handler, and then exit that same read-side
- critical section in the task that was interrupted, then you need
- to srcu_read_lock_raw() and srcu_read_unlock_raw(), which avoid
- the lockdep checking that would otherwise this practice illegal.
-
Also unlike other forms of RCU, explicit initialization
and cleanup is required via init_srcu_struct() and
cleanup_srcu_struct(). These are passed a "struct srcu_struct"
diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt
index 7dce8a17eac2..d8a502387397 100644
--- a/Documentation/RCU/torture.txt
+++ b/Documentation/RCU/torture.txt
@@ -182,12 +182,6 @@ torture_type The type of RCU to test, with string values as follows:
"srcu_expedited": srcu_read_lock(), srcu_read_unlock() and
synchronize_srcu_expedited().
- "srcu_raw": srcu_read_lock_raw(), srcu_read_unlock_raw(),
- and call_srcu().
-
- "srcu_raw_sync": srcu_read_lock_raw(), srcu_read_unlock_raw(),
- and synchronize_srcu().
-
"sched": preempt_disable(), preempt_enable(), and
call_rcu_sched().
diff --git a/Documentation/RCU/whatisRCU.txt b/Documentation/RCU/whatisRCU.txt
index 10df0b82f459..0f0fb7c432c2 100644
--- a/Documentation/RCU/whatisRCU.txt
+++ b/Documentation/RCU/whatisRCU.txt
@@ -842,9 +842,7 @@ SRCU: Critical sections Grace period Barrier
srcu_read_lock synchronize_srcu srcu_barrier
srcu_read_unlock call_srcu
- srcu_read_lock_raw synchronize_srcu_expedited
- srcu_read_unlock_raw
- srcu_dereference
+ srcu_dereference synchronize_srcu_expedited
SRCU: Initialization/cleanup
init_srcu_struct
@@ -865,38 +863,32 @@ list can be helpful:
a. Will readers need to block? If so, you need SRCU.
-b. Is it necessary to start a read-side critical section in a
- hardirq handler or exception handler, and then to complete
- this read-side critical section in the task that was
- interrupted? If so, you need SRCU's srcu_read_lock_raw() and
- srcu_read_unlock_raw() primitives.
-
-c. What about the -rt patchset? If readers would need to block
+b. What about the -rt patchset? If readers would need to block
in an non-rt kernel, you need SRCU. If readers would block
in a -rt kernel, but not in a non-rt kernel, SRCU is not
necessary.
-d. Do you need to treat NMI handlers, hardirq handlers,
+c. Do you need to treat NMI handlers, hardirq handlers,
and code segments with preemption disabled (whether
via preempt_disable(), local_irq_save(), local_bh_disable(),
or some other mechanism) as if they were explicit RCU readers?
If so, RCU-sched is the only choice that will work for you.
-e. Do you need RCU grace periods to complete even in the face
+d. Do you need RCU grace periods to complete even in the face
of softirq monopolization of one or more of the CPUs? For
example, is your code subject to network-based denial-of-service
attacks? If so, you need RCU-bh.
-f. Is your workload too update-intensive for normal use of
+e. Is your workload too update-intensive for normal use of
RCU, but inappropriate for other synchronization mechanisms?
If so, consider SLAB_DESTROY_BY_RCU. But please be careful!
-g. Do you need read-side critical sections that are respected
+f. Do you need read-side critical sections that are respected
even though they are in the middle of the idle loop, during
user-mode execution, or on an offlined CPU? If so, SRCU is the
only choice that will work for you.
-h. Otherwise, use RCU.
+g. Otherwise, use RCU.
Of course, this all assumes that you have determined that RCU is in fact
the right tool for your job.

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