Re: [kvm-unit-tests PATCH 08/10] arm/arm64: gic: Split check_acked() into two functions

[Alexandru Elisei <alexandru.elisei@arm.com>]

Hi Eric,

On 12/3/20 1:39 PM, Auger Eric wrote:
>
> On 11/25/20 4:51 PM, Alexandru Elisei wrote:
>> check_acked() has several peculiarities: is the only function among the
>> check_* functions which calls report() directly, it does two things
>> (waits for interrupts and checks for misfired interrupts) and it also
>> mixes printf, report_info and report calls.
>>
>> check_acked() also reports a pass and returns as soon all the target CPUs
>> have received interrupts, However, a CPU not having received an interrupt
>> *now* does not guarantee not receiving an eroneous interrupt if we wait
> erroneous
>> long enough.
>>
>> Rework the function by splitting it into two separate functions, each with
>> a single responsability: wait_for_interrupts(), which waits for the
>> expected interrupts to fire, and check_acked() which checks that interrupts
>> have been received as expected.
>>
>> wait_for_interrupts() also waits an extra 100 milliseconds after the
>> expected interrupts have been received in an effort to make sure we don't
>> miss misfiring interrupts.
>>
>> Splitting check_acked() into two functions will also allow us to
>> customize the behavior of each function in the future more easily
>> without using an unnecessarily long list of arguments for check_acked().
>>
>> CC: Andre Przywara <andre.przywara@arm.com>
>> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
>> ---
>>  arm/gic.c | 73 +++++++++++++++++++++++++++++++++++--------------------
>>  1 file changed, 47 insertions(+), 26 deletions(-)
>>
>> diff --git a/arm/gic.c b/arm/gic.c
>> index 544c283f5f47..dcdab7d5f39a 100644
>> --- a/arm/gic.c
>> +++ b/arm/gic.c
>> @@ -62,41 +62,42 @@ static void stats_reset(void)
>>  	}
>>  }
>>  
>> -static void check_acked(const char *testname, cpumask_t *mask)
>> +static void wait_for_interrupts(cpumask_t *mask)
>>  {
>> -	int missing = 0, extra = 0, unexpected = 0;
>>  	int nr_pass, cpu, i;
>> -	bool bad = false;
>>  
>>  	/* Wait up to 5s for all interrupts to be delivered */
>> -	for (i = 0; i < 50; ++i) {
>> +	for (i = 0; i < 50; i++) {
>>  		mdelay(100);
>>  		nr_pass = 0;
>>  		for_each_present_cpu(cpu) {
>> +			/*
>> +			 * A CPU having receied more than one interrupts will
> received
>> +			 * show up in check_acked(), and no matter how long we
>> +			 * wait it cannot un-receive it. Consier at least one
> consider

Will fix all three typos, thanks.

>> +			 * interrupt as a pass.
>> +			 */
>>  			nr_pass += cpumask_test_cpu(cpu, mask) ?
>> -				acked[cpu] == 1 : acked[cpu] == 0;
>> -			smp_rmb(); /* pairs with smp_wmb in ipi_handler */
>> -
>> -			if (bad_sender[cpu] != -1) {
>> -				printf("cpu%d received IPI from wrong sender %d\n",
>> -					cpu, bad_sender[cpu]);
>> -				bad = true;
>> -			}
>> -
>> -			if (bad_irq[cpu] != -1) {
>> -				printf("cpu%d received wrong irq %d\n",
>> -					cpu, bad_irq[cpu]);
>> -				bad = true;
>> -			}
>> +				acked[cpu] >= 1 : acked[cpu] == 0;
>>  		}
>> +
>>  		if (nr_pass == nr_cpus) {
>> -			report(!bad, "%s", testname);
>>  			if (i)
>> -				report_info("took more than %d ms", i * 100);
>> +				report_info("interrupts took more than %d ms", i * 100);
>> +			mdelay(100);
>>  			return;
>>  		}
>>  	}
>>  
>> +	report_info("interrupts timed-out (5s)");
>> +}
>> +
>> +static bool check_acked(cpumask_t *mask)
>> +{
>> +	int missing = 0, extra = 0, unexpected = 0;
>> +	bool pass = true;
>> +	int cpu;
>> +
>>  	for_each_present_cpu(cpu) {
>>  		if (cpumask_test_cpu(cpu, mask)) {
>>  			if (!acked[cpu])
>> @@ -107,11 +108,28 @@ static void check_acked(const char *testname, cpumask_t *mask)
>>  			if (acked[cpu])
>>  				++unexpected;
>>  		}
>> +		smp_rmb(); /* pairs with smp_wmb in ipi_handler */
>> +
>> +		if (bad_sender[cpu] != -1) {
>> +			report_info("cpu%d received IPI from wrong sender %d",
>> +					cpu, bad_sender[cpu]);
>> +			pass = false;
>> +		}
>> +
>> +		if (bad_irq[cpu] != -1) {
>> +			report_info("cpu%d received wrong irq %d",
>> +					cpu, bad_irq[cpu]);
>> +			pass = false;
>> +		}
>> +	}
>> +
>> +	if (missing || extra || unexpected) {
>> +		report_info("ACKS: missing=%d extra=%d unexpected=%d",
>> +				missing, extra, unexpected);
>> +		pass = false;
>>  	}
>>  
>> -	report(false, "%s", testname);
>> -	report_info("Timed-out (5s). ACKS: missing=%d extra=%d unexpected=%d",
>> -		    missing, extra, unexpected);
>> +	return pass;
>>  }
>>  
>>  static void check_spurious(void)
>> @@ -300,7 +318,8 @@ static void ipi_test_self(void)
>>  	cpumask_clear(&mask);
>>  	cpumask_set_cpu(smp_processor_id(), &mask);
>>  	gic->ipi.send_self();
>> -	check_acked("IPI: self", &mask);
>> +	wait_for_interrupts(&mask);
>> +	report(check_acked(&mask), "Interrupts received");
>>  	report_prefix_pop();
>>  }
>>  
>> @@ -315,7 +334,8 @@ static void ipi_test_smp(void)
>>  	for (i = smp_processor_id() & 1; i < nr_cpus; i += 2)
>>  		cpumask_clear_cpu(i, &mask);
>>  	gic_ipi_send_mask(IPI_IRQ, &mask);
>> -	check_acked("IPI: directed", &mask);
>> +	wait_for_interrupts(&mask);
>> +	report(check_acked(&mask), "Interrupts received");
> both ipi_test_smp and ipi_test_self are called from the same test so
> better to use different error messages like it was done originally.

I used the same error message because the tests have a different prefix
("target-list" versus "broadcast"). Do you think there are cases where that's not
enough?

Thanks,
Alex