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rcu: RCU-based detection of stalled CPUs for Classic RCU

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This patch adds stalled-CPU detection to Classic RCU.  This capability
is enabled by a new config variable CONFIG_RCU_CPU_STALL_DETECTOR, which
defaults disabled.

This is a debugging feature to detect infinite loops in kernel code, not
something that non-kernel-hackers would be expected to care about.

This feature can detect looping CPUs in !PREEMPT builds and looping CPUs
with preemption disabled in PREEMPT builds.  This is essentially a port of
this functionality from the treercu patch, replacing the stall debug patch
that is already in tip/core/rcu (commit 67182ae1c4).

The changes from the patch in tip/core/rcu include making the config
variable name match that in treercu, changing from seconds to jiffies to
avoid spurious warnings, and printing a boot message when this feature
is enabled.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul E. McKenney
2008-10-02 16:06:39 -07:00
committed by Ingo Molnar
parent b5259d9442
commit 2133b5d7ff
3 changed files with 96 additions and 84 deletions
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2
lib/Kconfig.debug
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@ -597,7 +597,7 @@ config RCU_TORTURE_TEST_RUNNABLE
Say N here if you want the RCU torture tests to start only
after being manually enabled via /proc.
config RCU_CPU_STALL
config RCU_CPU_STALL_DETECTOR
bool "Check for stalled CPUs delaying RCU grace periods"
depends on CLASSIC_RCU
default n