powerpc: Do not assign thread.tidr if already assigned

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
zero.

Fixes: ec233ede4c86("powerpc: Add support for setting SPRN_TIDR")
Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
[mpe: Modify to return 0 in the success case, not the TID value]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index d205b52e3850a07c42b13eef712ab37862e0adae..5acb5a176dbe5c8bffe6ddb7458b7d3ac2b7019f 100644 (file)
--- 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 0;
+
        rc = assign_thread_tidr();
        if (rc < 0)
                return rc;