On Wed, Mar 10, 2021 at 1:39 AM Alexander Duyck
<alexander.du...@gmail.com> wrote:
>
> On Mon, Mar 8, 2021 at 7:15 PM <xiangxia.m....@gmail.com> wrote:
> >
> > From: Tonghao Zhang <xiangxia.m....@gmail.com>
> >
> > Introduce a new function twsk_prot_init, inspired by
> > req_prot_init, to simplify the "proto_register" function.
> >
> > Signed-off-by: Tonghao Zhang <xiangxia.m....@gmail.com>
> > ---
> > net/core/sock.c | 44 ++++++++++++++++++++++++++++----------------
> > 1 file changed, 28 insertions(+), 16 deletions(-)
> >
> > diff --git a/net/core/sock.c b/net/core/sock.c
> > index 0ed98f20448a..610de4295101 100644
> > --- a/net/core/sock.c
> > +++ b/net/core/sock.c
> > @@ -3475,6 +3475,32 @@ static int req_prot_init(const struct proto *prot)
> > return 0;
> > }
> >
> > +static int twsk_prot_init(const struct proto *prot)
> > +{
> > + struct timewait_sock_ops *twsk_prot = prot->twsk_prot;
> > +
> > + if (!twsk_prot)
> > + return 0;
> > +
> > + twsk_prot->twsk_slab_name = kasprintf(GFP_KERNEL, "tw_sock_%s",
> > + prot->name);
> > + if (!twsk_prot->twsk_slab_name)
> > + return -ENOMEM;
> > +
> > + twsk_prot->twsk_slab =
> > + kmem_cache_create(twsk_prot->twsk_slab_name,
> > + twsk_prot->twsk_obj_size, 0,
> > + SLAB_ACCOUNT | prot->slab_flags,
> > + NULL);
> > + if (!twsk_prot->twsk_slab) {
> > + pr_crit("%s: Can't create timewait sock SLAB cache!\n",
> > + prot->name);
> > + return -ENOMEM;
> > + }
> > +
> > + return 0;
> > +}
> > +
>
> So one issue here is that you have two returns but they both have the
> same error clean-up outside of the function. It might make more sense
> to look at freeing the kasprintf if the slab allocation fails and then
> using the out_free_request_sock_slab jump label below if the slab
> allocation failed.
Hi, thanks for your review.
if twsk_prot_init failed, (kasprintf, or slab alloc), we will invoke
the tw_prot_cleanup() to clean up
the sources allocated.
1. kfree(twsk_prot->twsk_slab_name); // if name is NULL, kfree() will
return directly
2. kmem_cache_destroy(twsk_prot->twsk_slab); // if slab is NULL,
kmem_cache_destroy() will return directly too.
so we don't care what err in twsk_prot_init().
and req_prot_cleanup() will clean up all sources allocated for req_prot_init().
> > int proto_register(struct proto *prot, int alloc_slab)
> > {
> > int ret = -ENOBUFS;
> > @@ -3496,22 +3522,8 @@ int proto_register(struct proto *prot, int
> > alloc_slab)
> > if (req_prot_init(prot))
> > goto out_free_request_sock_slab;
> >
> > - if (prot->twsk_prot != NULL) {
> > - prot->twsk_prot->twsk_slab_name =
> > kasprintf(GFP_KERNEL, "tw_sock_%s", prot->name);
> > -
> > - if (prot->twsk_prot->twsk_slab_name == NULL)
> > - goto out_free_request_sock_slab;
> > -
> > - prot->twsk_prot->twsk_slab =
> > -
> > kmem_cache_create(prot->twsk_prot->twsk_slab_name,
> > -
> > prot->twsk_prot->twsk_obj_size,
> > - 0,
> > - SLAB_ACCOUNT |
> > - prot->slab_flags,
> > - NULL);
> > - if (prot->twsk_prot->twsk_slab == NULL)
> > - goto out_free_timewait_sock_slab;
> > - }
> > + if (twsk_prot_init(prot))
> > + goto out_free_timewait_sock_slab;
>
> So assuming the code above takes care of freeing the slab name in case
> of slab allocation failure then this would be better off jumping to
> out_free_request_sock_slab.
>
> > }
> >
> > mutex_lock(&proto_list_mutex);
> > --
> > 2.27.0
> >
--
Best regards, Tonghao
