diff options
Diffstat (limited to 'Documentation/irqflags-tracing.txt')
| -rw-r--r-- | Documentation/irqflags-tracing.txt | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/Documentation/irqflags-tracing.txt b/Documentation/irqflags-tracing.txt index f6da05670e16..bdd208259fb3 100644 --- a/Documentation/irqflags-tracing.txt +++ b/Documentation/irqflags-tracing.txt @@ -1,8 +1,10 @@ +======================= IRQ-flags state tracing +======================= -started by Ingo Molnar <mingo@redhat.com> +:Author: started by Ingo Molnar <mingo@redhat.com> -the "irq-flags tracing" feature "traces" hardirq and softirq state, in +The "irq-flags tracing" feature "traces" hardirq and softirq state, in that it gives interested subsystems an opportunity to be notified of every hardirqs-off/hardirqs-on, softirqs-off/softirqs-on event that happens in the kernel. @@ -14,7 +16,7 @@ CONFIG_PROVE_RWSEM_LOCKING will be offered on an architecture - these are locking APIs that are not used in IRQ context. (the one exception for rwsems is worked around) -architecture support for this is certainly not in the "trivial" +Architecture support for this is certainly not in the "trivial" category, because lots of lowlevel assembly code deal with irq-flags state changes. But an architecture can be irq-flags-tracing enabled in a rather straightforward and risk-free manner. @@ -41,7 +43,7 @@ irq-flags-tracing support: excluded from the irq-tracing [and lock validation] mechanism via lockdep_off()/lockdep_on(). -in general there is no risk from having an incomplete irq-flags-tracing +In general there is no risk from having an incomplete irq-flags-tracing implementation in an architecture: lockdep will detect that and will turn itself off. I.e. the lock validator will still be reliable. There should be no crashes due to irq-tracing bugs. (except if the assembly |