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SubjectRe: How to check whether executing in atomic context?
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On Tue, Oct 13, 2009 at 11:36 PM, Leonidas . <leonidas137@gmail.com> wrote:
> Hi List,
>
> I am working on a profiler kind of module, the exported apis of my
> module can be
> called from process context and interrupt context as well. Depending on the
> context I am called in, I need to call sleepable/nonsleepable variants
> of my internal
> bookkeeping functions.
>
> I am aware of in_interrupt() call which can be used to check current
> context and take action
> accordingly.
>
> Is there any api which can help figure out whether we are executing
> while hold a spinlock? I.e
> an api which can help figure out sleepable/nonsleepable context? If it
> is not there, what can
> be done for writing the same? Any pointers will be helpful.
>
> -Leo.
>

While searching through the sources, I found this,

97/*
98 * Are we running in atomic context? WARNING: this macro cannot
99 * always detect atomic context; in particular, it cannot know about
100 * held spinlocks in non-preemptible kernels. Thus it should not be
101 * used in the general case to determine whether sleeping is possible.
102 * Do not use in_atomic() in driver code.
103 */
104#define in_atomic() ((preempt_count() & ~PREEMPT_ACTIVE) !=
PREEMPT_INATOMIC_BASE)
105

this just complicates the matter, right? This does not work in general
case but I think this
will always work if the kernel is preemptible.

Is there no way to write a generic macro?


-Leo.


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