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| author |   Mark Rutland <mark.rutland@arm.com> | 2021-01-11 15:37:07 +0000 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2021-01-22 11:08:56 +0100 |
| commit | 997acaf6b4b59c6a9c259740312a69ea549cc684 (patch) | |
| tree | 5cd5df4d2df07bf6646a08658de2df458def237b /include/linux/irqflags.h | |
| parent | jump_label: Do not profile branch annotations (diff) | |
| download | linux-dev-997acaf6b4b59c6a9c259740312a69ea549cc684.tar.xz linux-dev-997acaf6b4b59c6a9c259740312a69ea549cc684.zip | |
lockdep: report broken irq restoration
We generally expect local_irq_save() and local_irq_restore() to be
paired and sanely nested, and so local_irq_restore() expects to be
called with irqs disabled. Thus, within local_irq_restore() we only
trace irq flag changes when unmasking irqs.
This means that a sequence such as:
| local_irq_disable();
| local_irq_save(flags);
| local_irq_enable();
| local_irq_restore(flags);
... is liable to break things, as the local_irq_restore() would mask
irqs without tracing this change. Similar problems may exist for
architectures whose arch_irq_restore() function depends on being called
with irqs disabled.
We don't consider such sequences to be a good idea, so let's define
those as forbidden, and add tooling to detect such broken cases.
This patch adds debug code to WARN() when raw_local_irq_restore() is
called with irqs enabled. As raw_local_irq_restore() is expected to pair
with raw_local_irq_save(), it should never be called with irqs enabled.
To avoid the possibility of circular header dependencies between
irqflags.h and bug.h, the warning is handled in a separate C file.
The new code is all conditional on a new CONFIG_DEBUG_IRQFLAGS symbol
which is independent of CONFIG_TRACE_IRQFLAGS. As noted above such cases
will confuse lockdep, so CONFIG_DEBUG_LOCKDEP now selects
CONFIG_DEBUG_IRQFLAGS.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210111153707.10071-1-mark.rutland@arm.com
Diffstat (limited to 'include/linux/irqflags.h')
| -rw-r--r-- | include/linux/irqflags.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h index 8de0e1373de7..600c10da321a 100644 --- a/include/linux/irqflags.h +++ b/include/linux/irqflags.h @@ -149,6 +149,17 @@ do { \ # define start_critical_timings() do { } while (0) #endif +#ifdef CONFIG_DEBUG_IRQFLAGS +extern void warn_bogus_irq_restore(void); +#define raw_check_bogus_irq_restore() \ + do { \ + if (unlikely(!arch_irqs_disabled())) \ + warn_bogus_irq_restore(); \ + } while (0) +#else +#define raw_check_bogus_irq_restore() do { } while (0) +#endif + /* * Wrap the arch provided IRQ routines to provide appropriate checks. */ @@ -162,6 +173,7 @@ do { \ #define raw_local_irq_restore(flags) \ do { \ typecheck(unsigned long, flags); \ + raw_check_bogus_irq_restore(); \ arch_local_irq_restore(flags); \ } while (0) #define raw_local_save_flags(flags) \ |