Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block

* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  cciss: fix build for PROC_FS disabled
  block: fix amiga and atari floppy driver compile warning
  blk-throttle: Fix calculation of max number of WRITES to be dispatched
  ioprio: grab rcu_read_lock in sys_ioprio_{set,get}()
  xen/blkfront: cope with backend that fail empty BLKIF_OP_WRITE_BARRIER requests
  xen/blkfront: Implement FUA with BLKIF_OP_WRITE_BARRIER
  xen/blkfront: change blk_shadow.request to proper pointer
  xen/blkfront: map REQ_FLUSH into a full barrier

1 files changed, 6 insertions, 25 deletions

diff --git a/fs/ioprio.c b/fs/ioprio.c
index 2f7d05c8992..7da2a06508e 100644
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -103,22 +103,15 @@ SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
 	}
 
 	ret = -ESRCH;
-	/*
-	 * We want IOPRIO_WHO_PGRP/IOPRIO_WHO_USER to be "atomic",
-	 * so we can't use rcu_read_lock(). See re-copy of ->ioprio
-	 * in copy_process().
-	 */
-	read_lock(&tasklist_lock);
+	rcu_read_lock();
 	switch (which) {
 		case IOPRIO_WHO_PROCESS:
-			rcu_read_lock();
 			if (!who)
 				p = current;
 			else
 				p = find_task_by_vpid(who);
 			if (p)
 				ret = set_task_ioprio(p, ioprio);
-			rcu_read_unlock();
 			break;
 		case IOPRIO_WHO_PGRP:
 			if (!who)
@@ -141,12 +134,7 @@ SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
 				break;
 
 			do_each_thread(g, p) {
-				int match;
-
-				rcu_read_lock();
-				match = __task_cred(p)->uid == who;
-				rcu_read_unlock();
-				if (!match)
+				if (__task_cred(p)->uid != who)
 					continue;
 				ret = set_task_ioprio(p, ioprio);
 				if (ret)
@@ -160,7 +148,7 @@ free_uid:
 			ret = -EINVAL;
 	}
 
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 	return ret;
 }
 
@@ -204,17 +192,15 @@ SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
 	int ret = -ESRCH;
 	int tmpio;
 
-	read_lock(&tasklist_lock);
+	rcu_read_lock();
 	switch (which) {
 		case IOPRIO_WHO_PROCESS:
-			rcu_read_lock();
 			if (!who)
 				p = current;
 			else
 				p = find_task_by_vpid(who);
 			if (p)
 				ret = get_task_ioprio(p);
-			rcu_read_unlock();
 			break;
 		case IOPRIO_WHO_PGRP:
 			if (!who)
@@ -241,12 +227,7 @@ SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
 				break;
 
 			do_each_thread(g, p) {
-				int match;
-
-				rcu_read_lock();
-				match = __task_cred(p)->uid == user->uid;
-				rcu_read_unlock();
-				if (!match)
+				if (__task_cred(p)->uid != user->uid)
 					continue;
 				tmpio = get_task_ioprio(p);
 				if (tmpio < 0)
@@ -264,6 +245,6 @@ SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
 			ret = -EINVAL;
 	}
 
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 	return ret;
 }