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Spin lock deadlock detection #1670

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merged 2 commits into from
Jul 15, 2017

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jenswi-linaro
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{
unsigned int retries = 0;
unsigned int reminder = 0;
assert(thread_foreign_intr_disabled());
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minor: empty line before the assert.

unsigned int retries = 0;
unsigned int reminder = 0;

while (!cpu_spin_trylock(&pager_spinlock)) {
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! or not ! ?

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@igoropaniuk igoropaniuk Jul 7, 2017

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@etienne-lms

/* returns 0 on locking success, non zero on failure */
unsigned int __cpu_spin_trylock(unsigned int *lock);
....
static inline bool cpu_spin_trylock(unsigned int *lock)
{
	unsigned int rc;

	assert(thread_foreign_intr_disabled());
	rc = __cpu_spin_trylock(lock);
	if (!rc)
		spinlock_count_incr();
	return !rc;
}

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I don't actually understand why cpu_spin_trylock() == !__cpu_spin_trylock(), which can throw into confusion

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I agree, it is confusing. It stems from strex returning 1 in <Rd> on failure and 0 on success and that __cpu_spin_trylock() tries to do the bare minimum.

The code here is correct though.

@jenswi-linaro
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Review comment addressed

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Reviewed-by: Igor Opaniuk <igor.opaniuk@linaro.org>

Attempts to detect and report deadlock on spin locks..

Reviewed-by: Igor Opaniuk <igor.opaniuk@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Adds more details to deadlock report inside pager.

Reviewed-by: Igor Opaniuk <igor.opaniuk@linaro.org>
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
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Tag applied

@jforissier jforissier merged commit 3078da8 into OP-TEE:master Jul 15, 2017
@jenswi-linaro jenswi-linaro deleted the spin_lock_deadlock branch July 17, 2017 06:45
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4 participants