Messages in this thread Patch in this message | | | Date | Wed, 20 Mar 2024 02:09:21 +0100 | From | "Jason A. Donenfeld" <> | Subject | Re: [PATCH] random: Fix the issue of '_might_sleep' function running in an atomic contex |
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On Tue, Mar 19, 2024 at 05:30:55PM +0800, Guoyong Wang wrote: > On Mon, 18 Mar 2024 21:00:42 +0100, Jason A. Donenfeld wrote: > > I'm wondering, though, rather than introducing a second function, maybe > > execute_in_process_context() should just gain a `&& !in_atomic()`. > > That'd make things a bit simpler. > > > However, I'm pretty sure in_atomic() isn't actually a reliable way of > > determining that, depending on config. So maybe this should just call > > the worker always (if system_wq isn't null). > > > Alternatively, any chance the call to add_input_randomness() could be > > moved outside the spinlock, or does this not look possible? > > Hi Jason, > > Thanks for your suggestions. > > I am inclined to accept your second suggestion. My reluctance to accept > the first is due to the concern that "&& !in_atomic()" could potentially > alter the original meaning of the 'execute_in_process_context' interface. > Regarding the third suggestion, modifying the logic associated with 'input' > is not recommended.
Doesn't something like the below seem simplest? Just move the call out of the spinlock and we're done.
diff --git a/drivers/input/input-core-private.h b/drivers/input/input-core-private.h index 116834cf8868..717f239e28d0 100644 --- a/drivers/input/input-core-private.h +++ b/drivers/input/input-core-private.h @@ -10,7 +10,7 @@ struct input_dev;
void input_mt_release_slots(struct input_dev *dev); -void input_handle_event(struct input_dev *dev, +bool input_handle_event(struct input_dev *dev, unsigned int type, unsigned int code, int value);
#endif /* _INPUT_CORE_PRIVATE_H */ diff --git a/drivers/input/input.c b/drivers/input/input.c index f71ea4fb173f..2faf46218c66 100644 --- a/drivers/input/input.c +++ b/drivers/input/input.c @@ -391,20 +391,22 @@ static void input_event_dispose(struct input_dev *dev, int disposition, } }
-void input_handle_event(struct input_dev *dev, +bool input_handle_event(struct input_dev *dev, unsigned int type, unsigned int code, int value) { int disposition; + bool should_contribute_to_rng = false;
lockdep_assert_held(&dev->event_lock);
disposition = input_get_disposition(dev, type, code, &value); if (disposition != INPUT_IGNORE_EVENT) { if (type != EV_SYN) - add_input_randomness(type, code, value); + should_contribute_to_rng = true;
input_event_dispose(dev, disposition, type, code, value); } + return should_contribute_to_rng; }
/** @@ -428,12 +430,15 @@ void input_event(struct input_dev *dev, unsigned int type, unsigned int code, int value) { unsigned long flags; + bool should_contribute_to_rng;
if (is_event_supported(type, dev->evbit, EV_MAX)) {
spin_lock_irqsave(&dev->event_lock, flags); - input_handle_event(dev, type, code, value); + should_contribute_to_rng = input_handle_event(dev, type, code, value); spin_unlock_irqrestore(&dev->event_lock, flags); + if (should_contribute_to_rng) + add_input_randomness(type, code, value); } } EXPORT_SYMBOL(input_event);
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