[PATCH v2 4/6] devres: handle zero size in devm_kmalloc()

Bartosz Golaszewski
2020-06-29T20:51:33Z

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Make devm_kmalloc() behave similarly to non-managed kmalloc(): return
ZERO_SIZE_PTR when requested size is 0. Update devm_kfree() to handle
this case.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
drivers/base/devres.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index 1df1fb10b2d9..ed615d3b9cf1 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -819,6 +819,9 @@ void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp)
{
struct devres *dr;

+ if (unlikely(!size))
+ return ZERO_SIZE_PTR;
+
/* use raw alloc_dr for kmalloc caller tracing */
dr = alloc_dr(devm_kmalloc_release, size, gfp, dev_to_node(dev));
if (unlikely(!dr))
@@ -950,10 +953,10 @@ void devm_kfree(struct device *dev, const void *p)
int rc;

/*
- * Special case: pointer to a string in .rodata returned by
- * devm_kstrdup_const().
+ * Special cases: pointer to a string in .rodata returned by
+ * devm_kstrdup_const() or NULL/ZERO ptr.
*/
- if (unlikely(is_kernel_rodata((unsigned long)p)))
+ if (unlikely(is_kernel_rodata((unsigned long)p) || ZERO_OR_NULL_PTR(p)))
return;

rc = devres_destroy(dev, devm_kmalloc_release,
--
2.26.1