2019-07-03 16:27:43

by Fuqian Huang

Subject: [PATCH v2 03/35] powerpc: Use kmemdup rather than duplicating its implementation

kmemdup is introduced to duplicate a region of memory in a neat way.
Rather than kmalloc/kzalloc + memcpy, which the programmer needs to
write the size twice (sometimes lead to mistakes), kmemdup improves
readability, leads to smaller code and also reduce the chances of mistakes.
Suggestion to use kmemdup rather than using kmalloc/kzalloc + memcpy.

Signed-off-by: Fuqian Huang <[email protected]>
---
Changes in v2:
- Fix a typo in commit message (memset -> memcpy)

arch/powerpc/platforms/pseries/dlpar.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index 7488e40f5e47..20fe7b79e09e 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -383,11 +383,10 @@ void queue_hotplug_event(struct pseries_hp_errorlog *hp_errlog)
struct pseries_hp_work *work;
struct pseries_hp_errorlog *hp_errlog_copy;

- hp_errlog_copy = kmalloc(sizeof(struct pseries_hp_errorlog),
+ hp_errlog_copy = kmemdup(hp_errlog, sizeof(struct pseries_hp_errorlog),
GFP_KERNEL);
if (!hp_errlog_copy)
return;
- memcpy(hp_errlog_copy, hp_errlog, sizeof(struct pseries_hp_errorlog));

work = kmalloc(sizeof(struct pseries_hp_work), GFP_KERNEL);
if (work) {
--
2.11.0

2019-07-09 15:17:36

by Nathan Lynch

Subject: Re: [PATCH v2 03/35] powerpc: Use kmemdup rather than duplicating its implementation

Fuqian Huang <[email protected]> writes:
> kmemdup is introduced to duplicate a region of memory in a neat way.
> Rather than kmalloc/kzalloc + memcpy, which the programmer needs to
> write the size twice (sometimes lead to mistakes), kmemdup improves
> readability, leads to smaller code and also reduce the chances of mistakes.
> Suggestion to use kmemdup rather than using kmalloc/kzalloc + memcpy.
>
> Signed-off-by: Fuqian Huang <[email protected]>
> ---
> Changes in v2:
> - Fix a typo in commit message (memset -> memcpy)

Thanks, but this and the unchecked kmalloc result (and incorrect gfp
flags) have already been addressed in commit
348ea30f51fc63ce3c7fd7dba6043e8e3ee0ef34 ("powerpc/pseries: avoid
blocking in irq when queuing hotplug events"):

https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=next&id=348ea30f51fc63ce3c7fd7dba6043e8e3ee0ef34