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-rw-r--r--ipc/sem.c56
1 files changed, 55 insertions, 1 deletions
diff --git a/ipc/sem.c b/ipc/sem.c
index c8e00f8..5215a81 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -90,6 +90,52 @@
#include <asm/uaccess.h>
#include "util.h"
+/* One semaphore structure for each semaphore in the system. */
+struct sem {
+ int semval; /* current value */
+ int sempid; /* pid of last operation */
+ struct list_head sem_pending; /* pending single-sop operations */
+};
+
+/* One queue for each sleeping process in the system. */
+struct sem_queue {
+ struct list_head simple_list; /* queue of pending operations */
+ struct list_head list; /* queue of pending operations */
+ struct task_struct *sleeper; /* this process */
+ struct sem_undo *undo; /* undo structure */
+ int pid; /* process id of requesting process */
+ int status; /* completion status of operation */
+ struct sembuf *sops; /* array of pending operations */
+ int nsops; /* number of operations */
+ int alter; /* does *sops alter the array? */
+};
+
+/* Each task has a list of undo requests. They are executed automatically
+ * when the process exits.
+ */
+struct sem_undo {
+ struct list_head list_proc; /* per-process list: *
+ * all undos from one process
+ * rcu protected */
+ struct rcu_head rcu; /* rcu struct for sem_undo */
+ struct sem_undo_list *ulp; /* back ptr to sem_undo_list */
+ struct list_head list_id; /* per semaphore array list:
+ * all undos for one array */
+ int semid; /* semaphore set identifier */
+ short *semadj; /* array of adjustments */
+ /* one per semaphore */
+};
+
+/* sem_undo_list controls shared access to the list of sem_undo structures
+ * that may be shared among all a CLONE_SYSVSEM task group.
+ */
+struct sem_undo_list {
+ atomic_t refcnt;
+ spinlock_t lock;
+ struct list_head list_proc;
+};
+
+
#define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS])
#define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm)
@@ -1426,6 +1472,8 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
queue.status = -EINTR;
queue.sleeper = current;
+
+sleep_again:
current->state = TASK_INTERRUPTIBLE;
sem_unlock(sma);
@@ -1460,7 +1508,6 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
* Array removed? If yes, leave without sem_unlock().
*/
if (IS_ERR(sma)) {
- error = -EIDRM;
goto out_free;
}
@@ -1479,6 +1526,13 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
*/
if (timeout && jiffies_left == 0)
error = -EAGAIN;
+
+ /*
+ * If the wakeup was spurious, just retry
+ */
+ if (error == -EINTR && !signal_pending(current))
+ goto sleep_again;
+
unlink_queue(sma, &queue);
out_unlock_free:
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