signal: Add restore_user_sigmask()

Refactor the logic to restore the sigmask before the syscall
returns into an api.
This is useful for versions of syscalls that pass in the
sigmask and expect the current->sigmask to be changed during
the execution and restored after the execution of the syscall.

With the advent of new y2038 syscalls in the subsequent patches,
we add two more new versions of the syscalls (for pselect, ppoll
and io_pgetevents) in addition to the existing native and compat
versions. Adding such an api reduces the logic that would need to
be replicated otherwise.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/signal.h b/include/linux/signal.h
index ce14b951befb..cc7e2c1cd444 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -275,6 +275,8 @@ extern int __group_send_sig_info(int, struct kernel_siginfo *, struct task_struc
 extern int sigprocmask(int, sigset_t *, sigset_t *);
 extern int set_user_sigmask(const sigset_t __user *usigmask, sigset_t *set,
         sigset_t *oldset, size_t sigsetsize);
+extern void restore_user_sigmask(const void __user *usigmask,
+                                 sigset_t *sigsaved);
 extern void set_current_blocked(sigset_t *);
 extern void __set_current_blocked(const sigset_t *);
 extern int show_unhandled_signals;