[PATH v3 net-next] net: remove member 'max' of struct scm_fp_list
From: yuan linyu <hidden>
Date: 2017-02-11 03:42:18
From: yuan linyu <redacted> '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 3, the worst case is new_fpl->count = SCM_MAX_FD, so do a full size dup, then 'max' field will always SCM_MAX_FD and it can be removed. Signed-off-by: yuan linyu <redacted> --- v2->v3: change scm_fp_dup() to do a full size dup v1->v2: update commit log to describe correct reason to remove 'max' include/net/scm.h | 3 +-- net/core/scm.c | 23 ++++++----------------- 2 files changed, 7 insertions(+), 19 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..fb3ab32 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)
@@ -336,12 +327,10 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl) if (!fpl) return NULL; - new_fpl = kmemdup(fpl, offsetof(struct scm_fp_list, fp[fpl->count]), - GFP_KERNEL); + new_fpl = kmemdup(fpl, sizeof(*fpl), GFP_KERNEL); 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;
--
2.7.4