Re: [PATCH] selftests: arm64: Fix redundancy of a testcase

[Dev Jain]

On 6/5/24 17:30, Mark Brown wrote:
> On Wed, Jun 05, 2024 at 05:24:48PM +0530, Dev Jain wrote:
> > Currently, we are writing the same value as we read, into the TLS
> > register; hence, we cannot confirm updation of the register, making the
> > testcase "verify_tpidr_one" redundant. Fix this; while at it, do a style
> > change.
> Please don't combine unrelated changes into a single patch.


I shall take care of that in the future.

> >   	/* ...write a new value.. */
> >   	write_iov.iov_len = sizeof(uint64_t);
> > -	write_val[0] = read_val[0]++;
> > +	write_val[0] = read_val[0] + 1;
> >   	ret = ptrace(PTRACE_SETREGSET, child, NT_ARM_TLS, &write_iov);
> >   	ksft_test_result(ret == 0, "write_tpidr_one\n");
> This is a good fix:
>
> Reviewed-by: Mark Brown <broonie@xxxxxxxxxx>


Thanks!

> > @@ -108,7 +108,7 @@ static void test_tpidr(pid_t child)
> >   		/* Writing only TPIDR... */
> >   		write_iov.iov_len = sizeof(uint64_t);
> >   		memcpy(write_val, read_val, sizeof(read_val));
> > -		write_val[0] += 1;
> > +		++write_val[0];
> I'm less convinced that this is a good style change.


Well, what I have seen usually is, when we add 1, we

use prefix/postfix increment, and do a "+=" when it

is not 1. But, I get your point: such style may confuse

people into thinking that we are doing an index/pointer

increment, since that is the usual usecase for this.