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authorPaul E. McKenney <paulmck@kernel.org>2020-06-30 13:22:54 -0700
committerPaul E. McKenney <paulmck@kernel.org>2020-09-04 11:52:50 -0700
commit35feb60474bf4f7fa7840e14fc7fd344996b919d (patch)
tree17030fd8b9c654eab6b9da001de1776ff95a2385 /lib
parente48c15b796d412ede883bb2ef7779b2a142f7962 (diff)
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kernel/smp: Provide CSD lock timeout diagnostics
This commit causes csd_lock_wait() to emit diagnostics when a CPU fails to respond quickly enough to one of the smp_call_function() family of function calls. These diagnostics are enabled by a new CSD_LOCK_WAIT_DEBUG Kconfig option that depends on DEBUG_KERNEL. This commit was inspired by an earlier patch by Josef Bacik. [ paulmck: Fix for syzbot+0f719294463916a3fc0e@syzkaller.appspotmail.com ] [ paulmck: Fix KASAN use-after-free issue reported by Qian Cai. ] [ paulmck: Fix botched nr_cpu_ids comparison per Dan Carpenter. ] [ paulmck: Apply Peter Zijlstra feedback. ] Link: https://lore.kernel.org/lkml/00000000000042f21905a991ecea@google.com Link: https://lore.kernel.org/lkml/0000000000002ef21705a9933cf3@google.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.debug11
1 files changed, 11 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index e068c3c7189a..86a35fdfe021 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1367,6 +1367,17 @@ config WW_MUTEX_SELFTEST
Say M if you want these self tests to build as a module.
Say N if you are unsure.
+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