[PATCH] alpha: Fix getxpid on alpha so it works for threads

While looking in the code I discovered that alpha has fallen behind because
it doesn't use sys_getppid.  The problem is that it doesn't follow the task
struct to the task_group_leader.

Acked-by: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 10 insertions, 7 deletions

diff --git a/arch/alpha/kernel/asm-offsets.c b/arch/alpha/kernel/asm-offsets.c
index 8f2e5c718b50..6c56c754a0b5 100644
--- a/arch/alpha/kernel/asm-offsets.c
+++ b/arch/alpha/kernel/asm-offsets.c
@@ -28,6 +28,7 @@ void foo(void)
         DEFINE(TASK_GID, offsetof(struct task_struct, gid));
         DEFINE(TASK_EGID, offsetof(struct task_struct, egid));
         DEFINE(TASK_REAL_PARENT, offsetof(struct task_struct, real_parent));
+        DEFINE(TASK_GROUP_LEADER, offsetof(struct task_struct, group_leader));
         DEFINE(TASK_TGID, offsetof(struct task_struct, tgid));
         BLANK();
 
diff --git a/arch/alpha/kernel/entry.S b/arch/alpha/kernel/entry.S
index e38671c922bc..7af15bf7e5ab 100644
--- a/arch/alpha/kernel/entry.S
+++ b/arch/alpha/kernel/entry.S
@@ -879,17 +879,19 @@ sys_getxpid:
 
         /* See linux/kernel/timer.c sys_getppid for discussion
            about this loop.  */
-        ldq     $3, TASK_REAL_PARENT($2)
-1:      ldl     $1, TASK_TGID($3)
+        ldq     $3, TASK_GROUP_LEADER($2)
+        ldq     $4, TASK_REAL_PARENT($3)
+        ldl     $0, TASK_TGID($2)
+1:      ldl     $1, TASK_TGID($4)
 #ifdef CONFIG_SMP
-        mov     $3, $4
+        mov     $4, $5
         mb
-        ldq     $3, TASK_REAL_PARENT($2)
-        cmpeq   $3, $4, $4
-        beq     $4, 1b
+        ldq     $3, TASK_GROUP_LEADER($2)
+        ldq     $4, TASK_REAL_PARENT($3)
+        cmpeq   $4, $5, $5
+        beq     $5, 1b
 #endif
         stq     $1, 80($sp)
-        ldl     $0, TASK_TGID($2)
         ret
 .end sys_getxpid