cp_abort is only required or user windows, because kernel context
must not be preempted between a copy/paste pair.
Without this patch, the init task gets used_vas set when it runs
the nx842_powernv_init initcall, which opens windows for kernel
usage.
used_vas is then never cleared anywhere, so it gets propagated
into all other tasks. It's a property of the address space, so it
should really be cleared when a new mm is created (or in dup_mmap
if the mmaps are marked as VM_DONTCOPY). For now we seem to have
no such driver, so leave that for another patch.
Cc: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/platforms/powernv/vas-window.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/platforms/powernv/vas-window.c
b/arch/powerpc/platforms/powernv/vas-window.c
index 2b3eb01ab110..b7c53a51c31b 100644
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -1063,16 +1063,16 @@ struct vas_window *vas_tx_win_open(int vasid, enum
vas_cop_type cop,
rc = PTR_ERR(txwin->paste_kaddr);
goto free_window;
}
+ } else {
+ /*
+ * A user mapping must ensure that context switch issues
+ * CP_ABORT for this thread.
+ */
+ rc = set_thread_uses_vas();
+ if (rc)
+ goto free_window;
}
- /*
- * Now that we have a send window, ensure context switch issues
- * CP_ABORT for this thread.
- */
- rc = -EINVAL;
- if (set_thread_uses_vas() < 0)
- goto free_window;
-
set_vinst_win(vinst, txwin);
return txwin;
--
2.15.1
