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authorpeterz@infradead.org <peterz@infradead.org>2020-07-27 14:48:52 +0200
committerIngo Molnar <mingo@kernel.org>2020-07-27 15:13:29 +0200
commited00495333ccc80fc8fb86fb43773c3c2a499466 (patch)
tree64882e5a738ab148341521d4ac598038ce8afd81 /kernel/locking
parentx86/entry: Fix NMI vs IRQ state tracking (diff)
downloadlinux-ed00495333ccc80fc8fb86fb43773c3c2a499466.tar.xz
linux-ed00495333ccc80fc8fb86fb43773c3c2a499466.zip
locking/lockdep: Fix TRACE_IRQFLAGS vs. NMIs
Prior to commit: 859d069ee1dd ("lockdep: Prepare for NMI IRQ state tracking") IRQ state tracking was disabled in NMIs due to nmi_enter() doing lockdep_off() -- with the obvious requirement that NMI entry call nmi_enter() before trace_hardirqs_off(). [ AFAICT, PowerPC and SH violate this order on their NMI entry ] However, that commit explicitly changed lockdep_hardirqs_*() to ignore lockdep_off() and breaks every architecture that has irq-tracing in it's NMI entry that hasn't been fixed up (x86 being the only fixed one at this point). The reason for this change is that by ignoring lockdep_off() we can: - get rid of 'current->lockdep_recursion' in lockdep_assert_irqs*() which was going to to give header-recursion issues with the seqlock rework. - allow these lockdep_assert_*() macros to function in NMI context. Restore the previous state of things and allow an architecture to opt-in to the NMI IRQ tracking support, however instead of relying on lockdep_off(), rely on in_nmi(), both are part of nmi_enter() and so over-all entry ordering doesn't need to change. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200727124852.GK119549@hirez.programming.kicks-ass.net
Diffstat (limited to 'kernel/locking')
-rw-r--r--kernel/locking/lockdep.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index d595623c4b34..8b0b28b4546b 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3712,6 +3712,9 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
* and not rely on hardware state like normal interrupts.
*/
if (unlikely(in_nmi())) {
+ if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
+ return;
+
/*
* Skip:
* - recursion check, because NMI can hit lockdep;
@@ -3773,7 +3776,10 @@ void noinstr lockdep_hardirqs_off(unsigned long ip)
* they will restore the software state. This ensures the software
* state is consistent inside NMIs as well.
*/
- if (unlikely(!in_nmi() && (current->lockdep_recursion & LOCKDEP_RECURSION_MASK)))
+ if (in_nmi()) {
+ if (!IS_ENABLED(CONFIG_TRACE_IRQFLAGS_NMI))
+ return;
+ } else if (current->lockdep_recursion & LOCKDEP_RECURSION_MASK)
return;
/*