Re: [PATCH] make setpriority POSIX compliant; introduce PRIO_THREAD extension

[Denys Vlasenko <dvlasenk@redhat.com>]

On Mon, 2008-09-01 at 16:12 +0200, Denys Vlasenko wrote:
> Patch is run tested. I will post test program etc as a reply.

Looks like Evolution word-wrapped the patch. Let me try again.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
--
vda


diff --git a/include/linux/resource.h b/include/linux/resource.h
index aaa423a..f292690 100644
--- a/include/linux/resource.h
+++ b/include/linux/resource.h
@@ -51,6 +51,7 @@ struct rlimit {
 #define	PRIO_PROCESS	0
 #define	PRIO_PGRP	1
 #define	PRIO_USER	2
+#define	PRIO_THREAD	3
 
 /*
  * Limit the stack by to some sane default: root can always
diff --git a/kernel/sys.c b/kernel/sys.c
index 038a7bc..d339c1a 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -142,9 +142,9 @@ asmlinkage long sys_setpriority(int which, int who, int niceval)
 	struct task_struct *g, *p;
 	struct user_struct *user;
 	int error = -EINVAL;
-	struct pid *pgrp;
+	struct pid *pgrp, *pid;
 
-	if (which > PRIO_USER || which < PRIO_PROCESS)
+	if (which > PRIO_THREAD || which < PRIO_PROCESS)
 		goto out;
 
 	/* normalize: avoid signed division (rounding problems) */
@@ -156,7 +156,7 @@ asmlinkage long sys_setpriority(int which, int who, int niceval)
 
 	read_lock(&tasklist_lock);
 	switch (which) {
-		case PRIO_PROCESS:
+		case PRIO_THREAD:
 			if (who)
 				p = find_task_by_vpid(who);
 			else
@@ -164,6 +164,19 @@ asmlinkage long sys_setpriority(int which, int who, int niceval)
 			if (p)
 				error = set_one_prio(p, niceval, error);
 			break;
+		case PRIO_PROCESS:
+			if (who)
+				pid = find_vpid(who);
+			else {
+				pid = task_pid(current);
+				who = current->pid;
+			}
+			do_each_pid_thread(pid, PIDTYPE_PID, p) {
+				if (who == p->pid || who == p->tgid) {
+					error = set_one_prio(p, niceval, error);
+				}
+			} while_each_pid_thread(pid, PIDTYPE_PID, p);
+			break;
 		case PRIO_PGRP:
 			if (who)
 				pgrp = find_vpid(who);
@@ -206,14 +219,14 @@ asmlinkage long sys_getpriority(int which, int who)
 	struct task_struct *g, *p;
 	struct user_struct *user;
 	long niceval, retval = -ESRCH;
-	struct pid *pgrp;
+	struct pid *pgrp, *pid;
 
-	if (which > PRIO_USER || which < PRIO_PROCESS)
+	if (which > PRIO_THREAD || which < PRIO_PROCESS)
 		return -EINVAL;
 
 	read_lock(&tasklist_lock);
 	switch (which) {
-		case PRIO_PROCESS:
+		case PRIO_THREAD:
 			if (who)
 				p = find_task_by_vpid(who);
 			else
@@ -224,6 +237,21 @@ asmlinkage long sys_getpriority(int which, int who)
 					retval = niceval;
 			}
 			break;
+		case PRIO_PROCESS:
+			if (who)
+				pid = find_vpid(who);
+			else {
+				pid = task_pid(current);
+				who = current->pid;
+			}
+			do_each_pid_thread(pid, PIDTYPE_PID, p) {
+				if (who == p->pid || who == p->tgid) {
+					niceval = 20 - task_nice(p);
+					if (niceval > retval)
+						retval = niceval;
+				}
+			} while_each_pid_thread(pid, PIDTYPE_PID, p);
+			break;
 		case PRIO_PGRP:
 			if (who)
 				pgrp = find_vpid(who);