- debugctl = prev->debugctlmsr;
-
-#ifdef CONFIG_X86_DS
- {
- unsigned long ds_prev = 0, ds_next = 0;
-
- if (prev->ds_ctx)
- ds_prev = (unsigned long)prev->ds_ctx->ds;
- if (next->ds_ctx)
- ds_next = (unsigned long)next->ds_ctx->ds;
-
- if (ds_next != ds_prev) {
- /*
- * We clear debugctl to make sure DS
- * is not in use when we change it:
- */
- debugctl = 0;
- update_debugctlmsr(0);
- wrmsrl(MSR_IA32_DS_AREA, ds_next);
- }
- }
-#endif /* CONFIG_X86_DS */
-
- if (next->debugctlmsr != debugctl)
+ if (test_tsk_thread_flag(next_p, TIF_DS_AREA_MSR) ||
+ test_tsk_thread_flag(prev_p, TIF_DS_AREA_MSR))
+ ds_switch_to(prev_p, next_p);
+ else if (next->debugctlmsr != prev->debugctlmsr)