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lockdep: Prepare for NMI IRQ state tracking 

There is no reason not to always, accurately, track IRQ state.

This change also makes IRQ state tracking ignore lockdep_off().

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200623083721.155449112@infradead.org
This commit is contained in:
Peter Zijlstra 2020-05-27 15:00:57 +02:00
parent 248591f5d2
commit 859d069ee1
1 changed files with 42 additions and 4 deletions
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46
kernel/locking/lockdep.c
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@ -395,7 +395,7 @@ void lockdep_init_task(struct task_struct *task)
static __always_inline void lockdep_recursion_finish(void)
{
if (WARN_ON_ONCE(--current->lockdep_recursion))
if (WARN_ON_ONCE((--current->lockdep_recursion) & LOCKDEP_RECURSION_MASK))
current->lockdep_recursion = 0;
}
@ -3646,7 +3646,16 @@ static void __trace_hardirqs_on_caller(void)
*/
void lockdep_hardirqs_on_prepare(unsigned long ip)
{
if (unlikely(!debug_locks || current->lockdep_recursion))
if (unlikely(!debug_locks))
return;
/*
* NMIs do not (and cannot) track lock dependencies, nothing to do.
*/
if (unlikely(in_nmi()))
return;
if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
return;
if (unlikely(current->hardirqs_enabled)) {
@ -3692,7 +3701,27 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
{
struct task_struct *curr = current;
if (unlikely(!debug_locks || curr->lockdep_recursion))
if (unlikely(!debug_locks))
return;
/*
* NMIs can happen in the middle of local_irq_{en,dis}able() where the
* tracking state and hardware state are out of sync.
*
* NMIs must save lockdep_hardirqs_enabled() to restore IRQ state from,
* and not rely on hardware state like normal interrupts.
*/
if (unlikely(in_nmi())) {
/*
* Skip:
* - recursion check, because NMI can hit lockdep;
* - hardware state check, because above;
* - chain_key check, see lockdep_hardirqs_on_prepare().
*/
goto skip_checks;
}
if (unlikely(current->lockdep_recursion & LOCKDEP_RECURSION_MASK))
return;
if (curr->hardirqs_enabled) {
@ -3720,6 +3749,7 @@ void noinstr lockdep_hardirqs_on(unsigned long ip)
DEBUG_LOCKS_WARN_ON(current->hardirq_chain_key !=
current->curr_chain_key);
skip_checks:
/* we'll do an OFF -> ON transition: */
curr->hardirqs_enabled = 1;
curr->hardirq_enable_ip = ip;
@ -3735,7 +3765,15 @@ void noinstr lockdep_hardirqs_off(unsigned long ip)
{
struct task_struct *curr = current;
if (unlikely(!debug_locks || curr->lockdep_recursion))
if (unlikely(!debug_locks))
return;
/*
* Matching lockdep_hardirqs_on(), allow NMIs in the middle of lockdep;
* 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)))
return;
/*