[PATCH v2 2/2] powerpc: Do not assign thread.tidr if already assigned

[Vaibhav Jain <vaibhav@linux.vnet.ibm.com>]

If set_thread_tidr() is called twice for same task_struct then it will
allocate a new tidr value to it leaving the previous value still
dangling in the vas_thread_ida table.

To fix this the patch changes set_thread_tidr() to check if a tidr
value is already assigned to the task_struct and if yes then returns
the existing value from function instead of allocating a new one.

Fixes: ec233ede4c86("powerpc: Add support for setting SPRN_TIDR")
Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
---
v2 ->	Fix minor spell errors in patch description
---
 arch/powerpc/kernel/process.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 5d8176c7c2d8..9a72282b022d 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1577,6 +1577,9 @@ int set_thread_tidr(struct task_struct *t)
 	if (t != current)
 		return -EINVAL;
 
+	if (t->thread.tidr)
+		return t->thread.tidr;
+
 	rc = assign_thread_tidr();
 	if (rc > 0) {
 		t->thread.tidr = rc;
-- 
2.14.3