Merge branch 'csd.2020.09.04a' into HEAD

csd.2020.09.04a: CPU smp_call_function() torture tests.

diff --cc Documentation/admin-guide/kernel-parameters.txt
Simple merge

diff --cc lib/Kconfig.debug
index 0c3a6c752ede23521b2045f1a8b6fccaeaedb49c,86a35fdfe021ecf7da314805e4e4010b84b1924c..4ac6f61b94754b6ce52d4f13f4730ee226e22524
--- 1/lib/Kconfig.debug
--- 2/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@@ -1367,16 -1367,17 +1367,27 @@@ config WW_MUTEX_SELFTES
          Say M if you want these self tests to build as a module.
          Say N if you are unsure.
  
 +config SCF_TORTURE_TEST
 +      tristate "torture tests for smp_call_function*()"
 +      depends on DEBUG_KERNEL
 +      select TORTURE_TEST
 +      help
 +        This option provides a kernel module that runs torture tests
 +        on the smp_call_function() family of primitives.  The kernel
 +        module may be built after the fact on the running kernel to
 +        be tested, if desired.
 +
+ config CSD_LOCK_WAIT_DEBUG
+       bool "Debugging for csd_lock_wait(), called from smp_call_function*()"
+       depends on DEBUG_KERNEL
+       depends on 64BIT
+       default n
+       help
+         This option enables debug prints when CPUs are slow to respond
+         to the smp_call_function*() IPI wrappers.  These debug prints
+         include the IPI handler function currently executing (if any)
+         and relevant stack traces.
+ 
  endmenu # lock debugging
  
  config TRACE_IRQFLAGS