diff options
| -rw-r--r-- | ipc/util.c | 53 |
1 files changed, 32 insertions, 21 deletions
diff --git a/ipc/util.c b/ipc/util.c index a2208d0f26b2..05cb9de66735 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -782,28 +782,37 @@ struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s) return iter->pid_ns; } -/* - * This routine locks the ipc structure found at least at position pos. +/** + * sysvipc_find_ipc - Find and lock the ipc structure based on seq pos + * @ids: ipc identifier set + * @pos: expected position + * + * The function finds an ipc structure, based on the sequence file + * position @pos. If there is no ipc structure at position @pos, then + * the successor is selected. + * If a structure is found, then it is locked (both rcu_read_lock() and + * ipc_lock_object()) and @pos is set to the position needed to locate + * the found ipc structure. + * If nothing is found (i.e. EOF), @pos is not modified. + * + * The function returns the found ipc structure, or NULL at EOF. */ -static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, - loff_t *new_pos) +static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t *pos) { - struct kern_ipc_perm *ipc = NULL; - int max_idx = ipc_get_maxidx(ids); + int tmpidx; + struct kern_ipc_perm *ipc; - if (max_idx == -1 || pos > max_idx) - goto out; + /* convert from position to idr index -> "-1" */ + tmpidx = *pos - 1; - for (; pos <= max_idx; pos++) { - ipc = idr_find(&ids->ipcs_idr, pos); - if (ipc != NULL) { - rcu_read_lock(); - ipc_lock_object(ipc); - break; - } + ipc = idr_get_next(&ids->ipcs_idr, &tmpidx); + if (ipc != NULL) { + rcu_read_lock(); + ipc_lock_object(ipc); + + /* convert from idr index to position -> "+1" */ + *pos = tmpidx + 1; } -out: - *new_pos = pos + 1; return ipc; } @@ -817,11 +826,13 @@ static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) if (ipc && ipc != SEQ_START_TOKEN) ipc_unlock(ipc); - return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); + /* Next -> search for *pos+1 */ + (*pos)++; + return sysvipc_find_ipc(&iter->ns->ids[iface->ids], pos); } /* - * File positions: pos 0 -> header, pos n -> ipc id = n - 1. + * File positions: pos 0 -> header, pos n -> ipc idx = n - 1. * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. */ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) @@ -846,8 +857,8 @@ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) if (*pos == 0) return SEQ_START_TOKEN; - /* Find the (pos-1)th ipc */ - return sysvipc_find_ipc(ids, *pos - 1, pos); + /* Otherwise return the correct ipc structure */ + return sysvipc_find_ipc(ids, pos); } static void sysvipc_proc_stop(struct seq_file *s, void *it) |