[PATCH v4] spi: ppc4xx: handle irq_of_parse_and_map() errors

[Ma Ke <make24@iscas.ac.cn>]

Zero and negative number is not a valid IRQ for in-kernel code and the
irq_of_parse_and_map() function returns zero on error.  So this check for
valid IRQs should only accept values > 0.

Fixes: 44dab88e7cc9 ("spi: add spi_ppc4xx driver")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
Changes in v4:
- fixed a typo in v3. Sorry for the error in the patch v3.
Changes in v3:
- removed Cc stable line as suggestions.
Changes in v2:
- added Cc stable line;
- added Fixes line.
---
 drivers/spi/spi-ppc4xx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/spi/spi-ppc4xx.c b/drivers/spi/spi-ppc4xx.c
index 942c3117ab3a..01fdecbf132d 100644
--- a/drivers/spi/spi-ppc4xx.c
+++ b/drivers/spi/spi-ppc4xx.c
@@ -413,6 +413,9 @@ static int spi_ppc4xx_of_probe(struct platform_device *op)
 
 	/* Request IRQ */
 	hw->irqnum = irq_of_parse_and_map(np, 0);
+	if (hw->irqnum <= 0)
+		goto free_host;
+
 	ret = request_irq(hw->irqnum, spi_ppc4xx_int,
 			  0, "spi_ppc4xx_of", (void *)hw);
 	if (ret) {
-- 
2.25.1