1 files changed, 30 insertions, 3 deletions

diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt
index d67068d0d2b9..375d3fb71437 100644
--- a/Documentation/RCU/torture.txt
+++ b/Documentation/RCU/torture.txt
@@ -69,6 +69,13 @@ onoff_interval
                 CPU-hotplug operations regardless of what value is
                 specified for onoff_interval.
 
+onoff_holdoff   The number of seconds to wait until starting CPU-hotplug
+                operations.  This would normally only be used when
+                rcutorture was built into the kernel and started
+                automatically at boot time, in which case it is useful
+                in order to avoid confusing boot-time code with CPUs
+                coming and going.
+
 shuffle_interval
                 The number of seconds to keep the test threads affinitied
                 to a particular subset of the CPUs, defaults to 3 seconds.
@@ -79,6 +86,24 @@ shutdown_secs	The number of seconds to run the test before terminating
                 zero, which disables test termination and system shutdown.
                 This capability is useful for automated testing.
 
+stall_cpu       The number of seconds that a CPU should be stalled while
+                within both an rcu_read_lock() and a preempt_disable().
+                This stall happens only once per rcutorture run.
+                If you need multiple stalls, use modprobe and rmmod to
+                repeatedly run rcutorture.  The default for stall_cpu
+                is zero, which prevents rcutorture from stalling a CPU.
+
+                Note that attempts to rmmod rcutorture while the stall
+                is ongoing will hang, so be careful what value you
+                choose for this module parameter!  In addition, too-large
+                values for stall_cpu might well induce failures and
+                warnings in other parts of the kernel.  You have been
+                warned!
+
+stall_cpu_holdoff
+                The number of seconds to wait after rcutorture starts
+                before stalling a CPU.  Defaults to 10 seconds.
+
 stat_interval   The number of seconds between output of torture
                 statistics (via printk()).  Regardless of the interval,
                 statistics are printed when the module is unloaded.
@@ -271,11 +296,13 @@ The following script may be used to torture RCU:
         #!/bin/sh
 
         modprobe rcutorture
-        sleep 100
+        sleep 3600
         rmmod rcutorture
         dmesg | grep torture:
 
 The output can be manually inspected for the error flag of "!!!".
 One could of course create a more elaborate script that automatically
-checked for such errors.  The "rmmod" command forces a "SUCCESS" or
-"FAILURE" indication to be printk()ed.
+checked for such errors.  The "rmmod" command forces a "SUCCESS",
+"FAILURE", or "RCU_HOTPLUG" indication to be printk()ed.  The first
+two are self-explanatory, while the last indicates that while there
+were no RCU failures, CPU-hotplug problems were detected.