commit 3185bd26188223195dc2e659a3d00219cad71a0f
author Al Viro <viro@ZenIV.linux.org.uk> Sat Oct 20 15:52:23 2012 +0100
committer Linus Torvalds <torvalds@linux-foundation.org> Wed Oct 24 05:16:45 2012 +0300
tree 1363b0619f9e416b308aee3c804fab13e6efa72c
parent 3d0ceac129f3ea0b125289055a3aa7519d38df77

alpha: separate thread-synchronous flags

... and fix the race in updating unaligned control ones

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/alpha/kernel/osf_sys.c

diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index 9eb0905..1e6956a 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -793,8 +793,7 @@
  	case GSI_UACPROC:
 		if (nbytes < sizeof(unsigned int))
 			return -EINVAL;
-		w = (current_thread_info()->flags >> ALPHA_UAC_SHIFT) &
-			UAC_BITMASK;
+		w = current_thread_info()->status & UAC_BITMASK;
 		if (put_user(w, (unsigned int __user *)buffer))
 			return -EFAULT;
  		return 1;
@@ -904,24 +903,20 @@
 		break;
 
  	case SSI_NVPAIRS: {
-		unsigned long v, w, i;
-		unsigned int old, new;
+		unsigned __user *p = buffer;
+		unsigned i;
 		
- 		for (i = 0; i < nbytes; ++i) {
+		for (i = 0, p = buffer; i < nbytes; ++i, p += 2) {
+			unsigned v, w, status;
 
- 			if (get_user(v, 2*i + (unsigned int __user *)buffer))
- 				return -EFAULT;
- 			if (get_user(w, 2*i + 1 + (unsigned int __user *)buffer))
+			if (get_user(v, p) || get_user(w, p + 1))
  				return -EFAULT;
  			switch (v) {
  			case SSIN_UACPROC:
-			again:
-				old = current_thread_info()->flags;
-				new = old & ~(UAC_BITMASK << ALPHA_UAC_SHIFT);
-				new = new | (w & UAC_BITMASK) << ALPHA_UAC_SHIFT;
-				if (cmpxchg(&current_thread_info()->flags,
-					    old, new) != old)
-					goto again;
+				w &= UAC_BITMASK;
+				status = current_thread_info()->status;
+				status = (status & ~UAC_BITMASK) | w;
+				current_thread_info()->status = status;
  				break;
  
  			default: