check IRQ affinity

check_irq_affinity.c

/**
 * Check the current irq affinity and core map to apply
 *
 * @param teb 		Pointer to our teb
 * @param irq 		IRQ line number to check
 * @param coremap	Pointer to a coremap to apply
 * @param is_equal	Pointer to variabl that will receive coremap comparison result
 *
 * @return 		BL_OK | BL_ERR
 */
__BL_STATIC int
bl_pal_linux_check_irq_affinity(bl_teb_t *teb,
                                unsigned int irq,
                                bl_pal_coremap_t *coremap,
                                unsigned int *is_equal)
{
	char irq_affinity_buf[PATH_MAX];
	char *line = NULL;
	FILE *file;
	size_t size = 0;
	ssize_t line_len;
	int res, i;
	bl_pal_coremap_t current_mask;

	bl_assert(teb != NULL);
	bl_assert(coremap != NULL);
	bl_assert(is_equal != NULL);

	bl_error_clear(teb);

	res = bl_string_print_ex(irq_affinity_buf,
	                         sizeof(irq_affinity_buf),
	                         BL_STR_F_NOTRUNCATE,
	                         NULL,
	                         "/proc/irq/%u/smp_affinity",
	                         irq);
	if (res != BL_OK)
	{
		bl_error_set(teb, BL_ERR_STRING_TRUNCATED);
		return BL_ERR;
	}

	file = fopen(irq_affinity_buf, "r");
	if (!file)
	{
		bl_error_set_aux(teb,
		                 BL_ERR_PAL_UNABLE_TO_OPEN_IRQ_AFFINITY,
		                 errno,
		                 "%s",
		                 irq_affinity_buf);
		return BL_ERR;
	}

	/* Initialise our current coremap */

	bl_pal_clear_coremap(&current_mask);

	/* Get the current irq affinity and instantiate the current_mask */

	line_len = getline(&line, &size, file);

	if (line_len > 0)
	{
		char *hex_words[bl_divide_round_up(BL_PAL_MAX_CORES, BL_BITS_PER_INT)];
		unsigned int
		    coremap_words[bl_divide_round_up(BL_PAL_MAX_CORES, BL_BITS_PER_INT)];

		/* Initialise our word values to zeroes */

		memset(coremap_words, 0, sizeof(coremap_words));

		/* Explode line into hexadecimal strings */

		unsigned int num_words =
		    bl_string_str2arr(line, ',', hex_words, bl_arraysz(hex_words));
		if (num_words > 0)
		{
			/* Loop over every word and convert the string to decimal value.
			 *
			 * Note the procfs orders the SMP affinity list from high order
			 * to low order, but the pal_coremap_set_words() API requires the
			 * word array to be in order from low order to high order.
			 *
			 * Thus we reorder the hex words being converted below, eg:
			 *
			 * 80000000,00000001 --> core96,core01
			 *
			 * And reversed into decimal words:
			 *
			 * coremap_words[0] = core01 (0x00000001)
			 * coremap_words[1] = core96 (0x80000000)
			 */

			for (i = num_words; i > 0; i--)
			{
				coremap_words[num_words - i] =
				    strtoul(hex_words[i - 1], NULL, 16);
			}

			/* Set words in current_mask */

			res = bl_pal_set_coremap_by_u32word(teb,
			                                    &current_mask,
			                                    BL_PAL_COREMAP_ALL,
			                                    coremap_words,
			                                    num_words);
		}
	}

	/* we use free instead of bl_free as getline contains an internal realloc which we
	 * do not track */

	free(line);
	fclose(file);

	if (res != BL_OK)
		return BL_ERR;

	/* Check if the desired coremap is equal to the current_mask in the
	 * /proc/irq/%s/smp_affinity file */

	*is_equal = bl_coremaps_equal(coremap, &current_mask, BL_PAL_MAX_CORES);

	return BL_OK;
}