| Message ID | 20220824080503.221680-1-chi.minghao@zte.com.cn (mailing list archive) |
|---|---|
| State | Rejected |
| Delegated to: | Leon Romanovsky |
| Headers | show |
| Series | infiniband: remove unnecessary null check | expand |
On 8/24/22 10:05, cgel.zte@gmail.com wrote: > From: Minghao Chi <chi.minghao@zte.com.cn> > > container_of is never null, so this null check is > unnecessary. > > Reported-by: Zeal Robot <zealci@zte.com.cn> > Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn> > --- > drivers/infiniband/sw/rdmavt/vt.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/drivers/infiniband/sw/rdmavt/vt.c b/drivers/infiniband/sw/rdmavt/vt.c > index 59481ae39505..b2d83b4958fc 100644 > --- a/drivers/infiniband/sw/rdmavt/vt.c > +++ b/drivers/infiniband/sw/rdmavt/vt.c > @@ -50,8 +50,6 @@ struct rvt_dev_info *rvt_alloc_device(size_t size, int nports) > struct rvt_dev_info *rdi; > > rdi = container_of(_ib_alloc_device(size), struct rvt_dev_info, ibdev); > - if (!rdi) > - return rdi; > > rdi->ports = kcalloc(nports, sizeof(*rdi->ports), GFP_KERNEL); > if (!rdi->ports) I believe this patch is incorrect because "_ib_alloc_device" may return a null pointer. Note that the first member of "rvt_dev_info" is "ib_device", so the check on container_of effectively checks if the allocation failed, which is necessary to check.
On Wed, Aug 24, 2022 at 10:15:56AM +0200, Niels Dossche wrote: > On 8/24/22 10:05, cgel.zte@gmail.com wrote: > > From: Minghao Chi <chi.minghao@zte.com.cn> > > > > container_of is never null, so this null check is > > unnecessary. > > > > Reported-by: Zeal Robot <zealci@zte.com.cn> > > Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn> > > --- > > drivers/infiniband/sw/rdmavt/vt.c | 2 -- > > 1 file changed, 2 deletions(-) > > > > diff --git a/drivers/infiniband/sw/rdmavt/vt.c b/drivers/infiniband/sw/rdmavt/vt.c > > index 59481ae39505..b2d83b4958fc 100644 > > --- a/drivers/infiniband/sw/rdmavt/vt.c > > +++ b/drivers/infiniband/sw/rdmavt/vt.c > > @@ -50,8 +50,6 @@ struct rvt_dev_info *rvt_alloc_device(size_t size, int nports) > > struct rvt_dev_info *rdi; > > > > rdi = container_of(_ib_alloc_device(size), struct rvt_dev_info, ibdev); > > - if (!rdi) > > - return rdi; > > > > rdi->ports = kcalloc(nports, sizeof(*rdi->ports), GFP_KERNEL); > > if (!rdi->ports) > > I believe this patch is incorrect because "_ib_alloc_device" may return a null pointer. > Note that the first member of "rvt_dev_info" is "ib_device", so the check on container_of effectively checks if the allocation failed, which is necessary to check. You are absolutely right, this container_of() and check later are done on purpose. It is open-coded variant of ib_alloc_device(...) macro. Thanks
diff --git a/drivers/infiniband/sw/rdmavt/vt.c b/drivers/infiniband/sw/rdmavt/vt.c index 59481ae39505..b2d83b4958fc 100644 --- a/drivers/infiniband/sw/rdmavt/vt.c +++ b/drivers/infiniband/sw/rdmavt/vt.c @@ -50,8 +50,6 @@ struct rvt_dev_info *rvt_alloc_device(size_t size, int nports) struct rvt_dev_info *rdi; rdi = container_of(_ib_alloc_device(size), struct rvt_dev_info, ibdev); - if (!rdi) - return rdi; rdi->ports = kcalloc(nports, sizeof(*rdi->ports), GFP_KERNEL); if (!rdi->ports)