hi,
yes, my misunderstanding.
it's error when use after dup.
can we do a full size(SCM_MAX_FD) dup?
On 六, 2017-02-11 at 10:36 +0800, yuan linyu wrote:
> From: yuan linyu <linyu.y...@alcatel-sbell.com.cn>
>
> 'max' only used at three places in scm.c,
> 1. in scm_fp_copy(), fpl->max = SCM_MAX_FD;
> 2. in scm_fp_copy(), if (fpl->count + num > fpl->max)
> 3. in scm_fp_dup(), new_fpl->max = new_fpl->count;
> at place 2, fpl->max can be replaced with SCM_MAX_FD.
> no other place read this 'max' again, so it can be removed.
>
> Signed-off-by: yuan linyu <linyu.y...@alcatel-sbell.com.cn>
> ---
> v1->v2:
> update commit log to describe correct reason to remove 'max'
>
> include/net/scm.h | 3 +--
> net/core/scm.c | 20 +++++---------------
> 2 files changed, 6 insertions(+), 17 deletions(-)
>
> diff --git a/include/net/scm.h b/include/net/scm.h
> index 59fa93c..1301227 100644
> --- a/include/net/scm.h
> +++ b/include/net/scm.h
> @@ -19,8 +19,7 @@ struct scm_creds {
> };
>
> struct scm_fp_list {
> - short count;
> - short max;
> + unsigned int count;
> struct user_struct *user;
> struct file *fp[SCM_MAX_FD];
> };
> diff --git a/net/core/scm.c b/net/core/scm.c
> index b6d8368..53679517 100644
> --- a/net/core/scm.c
> +++ b/net/core/scm.c
> @@ -69,15 +69,7 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct
> scm_fp_list **fplp)
> int *fdp = (int*)CMSG_DATA(cmsg);
> struct scm_fp_list *fpl = *fplp;
> struct file **fpp;
> - int i, num;
> -
> - num = (cmsg->cmsg_len - sizeof(struct cmsghdr))/sizeof(int);
> -
> - if (num <= 0)
> - return 0;
> -
> - if (num > SCM_MAX_FD)
> - return -EINVAL;
> + unsigned int i, num;
>
> if (!fpl)
> {
> @@ -86,18 +78,17 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct
> scm_fp_list **fplp)
> return -ENOMEM;
> *fplp = fpl;
> fpl->count = 0;
> - fpl->max = SCM_MAX_FD;
> fpl->user = NULL;
> }
> - fpp = &fpl->fp[fpl->count];
>
> - if (fpl->count + num > fpl->max)
> + num = (cmsg->cmsg_len - sizeof(struct cmsghdr))/sizeof(int);
> + if (fpl->count + num > SCM_MAX_FD)
> return -EINVAL;
>
> /*
> * Verify the descriptors and increment the usage count.
> */
> -
> + fpp = &fpl->fp[fpl->count];
> for (i=0; i< num; i++)
> {
> int fd = fdp[i];
> @@ -112,7 +103,7 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct
> scm_fp_list **fplp)
> if (!fpl->user)
> fpl->user = get_uid(current_user());
>
> - return num;
> + return 0;
> }
>
> void __scm_destroy(struct scm_cookie *scm)
> @@ -341,7 +332,6 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
> if (new_fpl) {
> for (i = 0; i < fpl->count; i++)
> get_file(fpl->fp[i]);
> - new_fpl->max = new_fpl->count;
> new_fpl->user = get_uid(fpl->user);
> }
> return new_fpl;
