Hi Bartosz, On 29/06/2020 07:50, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <[email protected]> > > 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 <[email protected]> > --- > 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,
This change caught a bug in one of our Tegra drivers, which I am in the process of fixing. Once I bisected to this commit it was easy to track down, but I am wondering if there is any reason why we don't add a WARN_ON() if size is 0 in devm_kmalloc? It was essentially what I ended up doing to find the bug. Jon -- nvpublic
