Re: [V2, 06/12] selftests, powerpc: Add test for system wide DSCR default

[Michael Ellerman <mpe@ellerman.id.au>]

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On Tue, 2015-13-01 at 10:22:34 UTC, Anshuman Khandual wrote:
> This patch adds a test case for the system wide DSCR default
> value, which when changed through it's sysfs interface must
> be visible to all threads reading DSCR either through the
> privilege state SPR or the problem state SPR. The DSCR value
> change should be immediate as well.
 
...

> +
> +/* Default DSCR access */
> +unsigned long get_default_dscr(void)
> +{
> +	int fd = -1;
> +	char buf[16];
> +	unsigned long val;
> +
> +	if (fd == -1) {
> +		fd = open(DSCR_DEFAULT, O_RDONLY);
> +		if (fd == -1) {
> +			perror("open() failed\n");
> +			exit(1);
> +		}
> +	}
> +	memset(buf, 0, sizeof(buf));
> +	lseek(fd, 0, SEEK_SET);
> +	read(fd, buf, sizeof(buf));


This and the other tests are failing to build:

    In file included from dscr_default_test.c:16:0:
    dscr.h: In function ‘get_default_dscr’:
    dscr.h:93:6: error: ignoring return value of ‘read’, declared with attribute warn_unused_result [-Werror=unused-result]
      read(fd, buf, sizeof(buf));
          ^
    dscr.h: In function ‘set_default_dscr’:
    dscr.h:112:7: error: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Werror=unused-result]
      write(fd, buf, strlen(buf));
           ^
    cc1: all warnings being treated as errors

cheers