[PATCH] semtimedop - semop() with a timeout

Patch from Mark Fasheh <mark.fasheh@oracle.com> (plus a few cleanups
and a speedup from yours truly)

Adds the semtimedop() function - semop with a timeout.  Solaris has
this.  It's apparently worth a couple of percent to Oracle throughput
and given the simplicity, that is sufficient benefit for inclusion IMO.

This patch hooks up semtimedop() only for ia64 and ia32.

arch/i386/kernel/sys_i386.c

@@ -140,7 +140,11 @@ asmlinkage int sys_ipc (uint call, int first, int second,
 
 	switch (call) {
 	case SEMOP:
-		return sys_semop (first, (struct sembuf *)ptr, second);
+		return sys_semtimedop (first, (struct sembuf *)ptr, second, NULL);
+	case SEMTIMEDOP:
+		return sys_semtimedop(first, (struct sembuf *)ptr, second,
+					(const struct timespec *)fifth);
+
 	case SEMGET:
 		return sys_semget (first, second, third);
 	case SEMCTL: {

arch/ia64/ia32/sys_ia32.c

@@ -2124,6 +2124,7 @@ struct ipc_kludge {
 #define SEMOP		 1
 #define SEMGET		 2
 #define SEMCTL		 3
+#define SEMTIMEDOP	 4
 #define MSGSND		11
 #define MSGRCV		12
 #define MSGGET		13

arch/ia64/kernel/entry.S

@@ -1254,7 +1254,7 @@ sys_call_table:
 	data8 sys_epoll_create
 	data8 sys_epoll_ctl
 	data8 sys_epoll_wait			// 1245
-	data8 ia64_ni_syscall
+	data8 sys_semtimedop
 	data8 ia64_ni_syscall
 	data8 ia64_ni_syscall
 	data8 ia64_ni_syscall

include/asm-i386/ipc.h

@@ -14,6 +14,7 @@ struct ipc_kludge {
 #define SEMOP		 1
 #define SEMGET		 2
 #define SEMCTL		 3
+#define SEMTIMEDOP	 4
 #define MSGSND		11
 #define MSGRCV		12
 #define MSGGET		13

include/asm-ia64/unistd.h

@@ -235,6 +235,7 @@
 #define __NR_epoll_create		1243
 #define __NR_epoll_ctl			1244
 #define __NR_epoll_wait			1245
+#define __NR_semtimedop			1246
 
 #if !defined(__ASSEMBLY__) && !defined(ASSEMBLER)
 

include/linux/sem.h

@@ -140,6 +140,8 @@ struct sysv_sem {
 asmlinkage long sys_semget (key_t key, int nsems, int semflg);
 asmlinkage long sys_semop (int semid, struct sembuf *sops, unsigned nsops);
 asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg);
+asmlinkage long sys_semtimedop(int semid, struct sembuf *sops,
+			unsigned nsops, const struct timespec *timeout);
 
 #endif /* __KERNEL__ */
 

ipc/sem.c

@@ -62,6 +62,7 @@
 #include <linux/spinlock.h>
 #include <linux/init.h>
 #include <linux/proc_fs.h>
+#include <linux/time.h>
 #include <linux/smp_lock.h>
 #include <linux/security.h>
 #include <asm/uaccess.h>
@@ -968,6 +969,12 @@ static int alloc_undo(struct sem_array *sma, struct sem_undo** unp, int semid, i
 }
 
 asmlinkage long sys_semop (int semid, struct sembuf *tsops, unsigned nsops)
+{
+	return sys_semtimedop(semid, tsops, nsops, NULL);
+}
+
+asmlinkage long sys_semtimedop(int semid, struct sembuf *tsops,
+			unsigned nsops, const struct timespec *timeout)
 {
 	int error = -EINVAL;
 	struct sem_array *sma;
@@ -976,7 +983,7 @@ asmlinkage long sys_semop (int semid, struct sembuf *tsops, unsigned nsops)
 	struct sem_undo *un;
 	int undos = 0, decrease = 0, alter = 0;
 	struct sem_queue queue;
-
+	unsigned long jiffies_left = 0;
 
 	if (nsops < 1 || semid < 0)
 		return -EINVAL;
@@ -991,6 +998,19 @@ asmlinkage long sys_semop (int semid, struct sembuf *tsops, unsigned nsops)
 		error=-EFAULT;
 		goto out_free;
 	}
+	if (timeout) {
+		struct timespec _timeout;
+		if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) {
+			error = -EFAULT;
+			goto out_free;
+		}
+		if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 ||
+			_timeout.tv_nsec >= 1000000000L) {
+			error = -EINVAL;
+			goto out_free;
+		}
+		jiffies_left = timespec_to_jiffies(&_timeout);
+	}
 	lock_semundo();
 	sma = sem_lock(semid);
 	error=-EINVAL;
@@ -1058,6 +1078,9 @@ asmlinkage long sys_semop (int semid, struct sembuf *tsops, unsigned nsops)
 		sem_unlock(sma);
 		unlock_semundo();
 
+		if (timeout)
+			jiffies_left = schedule_timeout(jiffies_left);
+		else
 			schedule();
 
 		lock_semundo();
@@ -1084,6 +1107,8 @@ asmlinkage long sys_semop (int semid, struct sembuf *tsops, unsigned nsops)
 				break;
 		} else {
 			error = queue.status;
+			if (error == -EINTR && timeout && jiffies_left == 0)
+				error = -EAGAIN;
 			if (queue.prev) /* got Interrupt */
 				break;
 			/* Everything done by update_queue */

ipc/util.c

@@ -562,6 +562,13 @@ asmlinkage long sys_semop (int semid, struct sembuf *sops, unsigned nsops)
 	return -ENOSYS;
 }
 
+asmlinkage long sys_semtimedop(int semid, struct sembuf *sops, unsigned nsops,
+				const struct timespec *timeout)
+{
+	return -ENOSYS;
+}
+
+
 asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg)
 {
 	return -ENOSYS;