Merge tag 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck...

[linux-imx.git] / ipc / sem.c

diff --git a/ipc/sem.c b/ipc/sem.c
index 6291257ee0498e9976e1d0bf5bcea250ee95f93d..41088899783d4106140333014a722da531494838 100644 (file)
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -99,6 +99,7 @@ struct sem {
                                        /* that alter the semaphore */
        struct list_head pending_const; /* pending single-sop operations */
                                        /* that do not alter the semaphore*/
+       time_t  sem_otime;      /* candidate for sem_otime */
 } ____cacheline_aligned_in_smp;
 
 /* One queue for each sleeping process in the system. */
@@ -153,12 +154,15 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
 #define SEMOPM_FAST    64  /* ~ 372 bytes on stack */
 
 /*
- * linked list protection:
+ * Locking:
  *     sem_undo.id_next,
+ *     sem_array.complex_count,
  *     sem_array.pending{_alter,_cont},
- *     sem_array.sem_undo: sem_lock() for read/write
+ *     sem_array.sem_undo: global sem_lock() for read/write
  *     sem_undo.proc_next: only "current" is allowed to read/write that field.
  *     
+ *     sem_array.sem_base[i].pending_{const,alter}:
+ *             global or semaphore sem_lock() for read/write
  */
 
 #define sc_semmsl      sem_ctls[0]
@@ -535,12 +539,19 @@ SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg)
        return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params);
 }
 
-/*
- * Determine whether a sequence of semaphore operations would succeed
- * all at once. Return 0 if yes, 1 if need to sleep, else return error code.
+/** perform_atomic_semop - Perform (if possible) a semaphore operation
+ * @sma: semaphore array
+ * @sops: array with operations that should be checked
+ * @nsems: number of sops
+ * @un: undo array
+ * @pid: pid that did the change
+ *
+ * Returns 0 if the operation was possible.
+ * Returns 1 if the operation is impossible, the caller must sleep.
+ * Negative values are error codes.
  */
 
-static int try_atomic_semop (struct sem_array * sma, struct sembuf * sops,
+static int perform_atomic_semop(struct sem_array *sma, struct sembuf *sops,
                             int nsops, struct sem_undo *un, int pid)
 {
        int result, sem_op;
@@ -723,8 +734,8 @@ static int wake_const_ops(struct sem_array *sma, int semnum,
                q = container_of(walk, struct sem_queue, list);
                walk = walk->next;
 
-               error = try_atomic_semop(sma, q->sops, q->nsops,
-                                               q->undo, q->pid);
+               error = perform_atomic_semop(sma, q->sops, q->nsops,
+                                                q->undo, q->pid);
 
                if (error <= 0) {
                        /* operation completed, remove from queue & wakeup */
@@ -837,7 +848,7 @@ again:
                if (semnum != -1 && sma->sem_base[semnum].semval == 0)
                        break;
 
-               error = try_atomic_semop(sma, q->sops, q->nsops,
+               error = perform_atomic_semop(sma, q->sops, q->nsops,
                                         q->undo, q->pid);
 
                /* Does q->sleeper still need to sleep? */
@@ -911,8 +922,14 @@ static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsop
                        }
                }
        }
-       if (otime)
-               sma->sem_otime = get_seconds();
+       if (otime) {
+               if (sops == NULL) {
+                       sma->sem_base[0].sem_otime = get_seconds();
+               } else {
+                       sma->sem_base[sops[0].sem_num].sem_otime =
+                                                               get_seconds();
+               }
+       }
 }
 
 
@@ -1058,6 +1075,21 @@ static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in,
        }
 }
 
+static time_t get_semotime(struct sem_array *sma)
+{
+       int i;
+       time_t res;
+
+       res = sma->sem_base[0].sem_otime;
+       for (i = 1; i < sma->sem_nsems; i++) {
+               time_t to = sma->sem_base[i].sem_otime;
+
+               if (to > res)
+                       res = to;
+       }
+       return res;
+}
+
 static int semctl_nolock(struct ipc_namespace *ns, int semid,
                         int cmd, int version, void __user *p)
 {
@@ -1131,9 +1163,9 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid,
                        goto out_unlock;
 
                kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
-               tbuf.sem_otime  = sma->sem_otime;
-               tbuf.sem_ctime  = sma->sem_ctime;
-               tbuf.sem_nsems  = sma->sem_nsems;
+               tbuf.sem_otime = get_semotime(sma);
+               tbuf.sem_ctime = sma->sem_ctime;
+               tbuf.sem_nsems = sma->sem_nsems;
                rcu_read_unlock();
                if (copy_semid_to_user(p, &tbuf, version))
                        return -EFAULT;
@@ -1664,7 +1696,6 @@ static int get_queue_result(struct sem_queue *q)
        return error;
 }
 
-
 SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
                unsigned, nsops, const struct timespec __user *, timeout)
 {
@@ -1762,7 +1793,8 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
        if (un && un->semid == -1)
                goto out_unlock_free;
 
-       error = try_atomic_semop (sma, sops, nsops, un, task_tgid_vnr(current));
+       error = perform_atomic_semop(sma, sops, nsops, un,
+                                       task_tgid_vnr(current));
        if (error <= 0) {
                if (alter && error == 0)
                        do_smart_update(sma, sops, nsops, 1, &tasks);
@@ -2025,6 +2057,9 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
 {
        struct user_namespace *user_ns = seq_user_ns(s);
        struct sem_array *sma = it;
+       time_t sem_otime;
+
+       sem_otime = get_semotime(sma);
 
        return seq_printf(s,
                          "%10d %10d  %4o %10u %5u %5u %5u %5u %10lu %10lu\n",
@@ -2036,7 +2071,7 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
                          from_kgid_munged(user_ns, sma->sem_perm.gid),
                          from_kuid_munged(user_ns, sma->sem_perm.cuid),
                          from_kgid_munged(user_ns, sma->sem_perm.cgid),
-                         sma->sem_otime,
+                         sem_otime,
                          sma->sem_ctime);
 }
 #endif