aio: implement io_pgetevents

This is the io_getevents equivalent of ppoll/pselect and allows to
properly mix signals and aio completions (especially with IOCB_CMD_POLL)
and atomically executes the following sequence:

	sigset_t origmask;

	pthread_sigmask(SIG_SETMASK, &sigmask, &origmask);
	ret = io_getevents(ctx, min_nr, nr, events, timeout);
	pthread_sigmask(SIG_SETMASK, &origmask, NULL);

Note that unlike many other signal related calls we do not pass a sigmask
size, as that would get us to 7 arguments, which aren't easily supported
by the syscall infrastructure.  It seems a lot less painful to just add a
new syscall variant in the unlikely case we're going to increase the
sigset size.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

2 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 081281ad5772..ad192057b887 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -330,6 +330,7 @@ extern int put_compat_rusage(const struct rusage *,
                              struct compat_rusage __user *);
 
 struct compat_siginfo;
+struct __compat_aio_sigset;
 
 struct compat_dirent {
         u32             d_ino;
@@ -553,6 +554,12 @@ asmlinkage long compat_sys_io_getevents(compat_aio_context_t ctx_id,
                                         compat_long_t nr,
                                         struct io_event __user *events,
                                         struct compat_timespec __user *timeout);
+asmlinkage long compat_sys_io_pgetevents(compat_aio_context_t ctx_id,
+                                        compat_long_t min_nr,
+                                        compat_long_t nr,
+                                        struct io_event __user *events,
+                                        struct compat_timespec __user *timeout,
+                                        const struct __compat_aio_sigset __user *usig);
 
 /* fs/cookies.c */
 asmlinkage long compat_sys_lookup_dcookie(u32, u32, char __user *, compat_size_t);
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 70fcda1a9049..811172fcb916 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -290,6 +290,12 @@ asmlinkage long sys_io_getevents(aio_context_t ctx_id,
                                 long nr,
                                 struct io_event __user *events,
                                 struct timespec __user *timeout);
+asmlinkage long sys_io_pgetevents(aio_context_t ctx_id,
+                                long min_nr,
+                                long nr,
+                                struct io_event __user *events,
+                                struct timespec __user *timeout,
+                                const struct __aio_sigset *sig);
 
 /* fs/xattr.c */
 asmlinkage long sys_setxattr(const char __user *path, const char __user *name,