[PATCH 7/7] aio: implement io_pgetevents

From: Christoph Hellwig
Date: Wed May 02 2018 - 17:15:36 EST

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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@xxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
arch/x86/entry/syscalls/syscall_32.tbl | 1 +
arch/x86/entry/syscalls/syscall_64.tbl | 1 +
fs/aio.c | 114 ++++++++++++++++++++++---
include/linux/compat.h | 7 ++
include/linux/syscalls.h | 6 ++
include/uapi/asm-generic/unistd.h | 4 +-
include/uapi/linux/aio_abi.h | 6 ++
kernel/sys_ni.c | 2 +
8 files changed, 130 insertions(+), 11 deletions(-)

diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index d6b27dab1b30..14a2f996e543 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -396,3 +396,4 @@
382 i386 pkey_free sys_pkey_free __ia32_sys_pkey_free
383 i386 statx sys_statx __ia32_sys_statx
384 i386 arch_prctl sys_arch_prctl __ia32_compat_sys_arch_prctl
+385 i386 io_pgetevents sys_io_pgetevents __ia32_compat_sys_io_pgetevents
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 4dfe42666d0c..cd36232ab62f 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -341,6 +341,7 @@
330 common pkey_alloc __x64_sys_pkey_alloc
331 common pkey_free __x64_sys_pkey_free
332 common statx __x64_sys_statx
+333 common io_pgetevents __x64_sys_io_pgetevents

#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/aio.c b/fs/aio.c
index 61d2e6942951..f3eae5d5771b 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1303,10 +1303,6 @@ static long read_events(struct kioctx *ctx, long min_nr, long nr,
wait_event_interruptible_hrtimeout(ctx->wait,
aio_read_events(ctx, min_nr, nr, event, &ret),
until);
-
- if (!ret && signal_pending(current))
- ret = -EINTR;
-
return ret;
}

@@ -1921,13 +1917,60 @@ SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
struct timespec __user *, timeout)
{
struct timespec64 ts;
+ int ret;
+
+ if (timeout && unlikely(get_timespec64(&ts, timeout)))
+ return -EFAULT;
+
+ ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
+ if (!ret && signal_pending(current))
+ ret = -EINTR;
+ return ret;
+}

- if (timeout) {
- if (unlikely(get_timespec64(&ts, timeout)))
+SYSCALL_DEFINE6(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 __user *, usig)
+{
+ struct __aio_sigset ksig = { NULL, };
+ sigset_t ksigmask, sigsaved;
+ struct timespec64 ts;
+ int ret;
+
+ if (timeout && unlikely(get_timespec64(&ts, timeout)))
+ return -EFAULT;
+
+ if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
+ return -EFAULT;
+
+ if (ksig.sigmask) {
+ if (ksig.sigsetsize != sizeof(sigset_t))
+ return -EINVAL;
+ if (copy_from_user(&ksigmask, ksig.sigmask, sizeof(ksigmask)))
return -EFAULT;
+ sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
+ sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+ }
+
+ ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
+ if (signal_pending(current)) {
+ if (ksig.sigmask) {
+ current->saved_sigmask = sigsaved;
+ set_restore_sigmask();
+ }
+
+ if (!ret)
+ ret = -ERESTARTNOHAND;
+ } else {
+ if (ksig.sigmask)
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
}

- return do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
+ return ret;
}

#ifdef CONFIG_COMPAT
@@ -1938,13 +1981,64 @@ COMPAT_SYSCALL_DEFINE5(io_getevents, compat_aio_context_t, ctx_id,
struct compat_timespec __user *, timeout)
{
struct timespec64 t;
+ int ret;
+
+ if (timeout && compat_get_timespec64(&t, timeout))
+ return -EFAULT;
+
+ ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
+ if (!ret && signal_pending(current))
+ ret = -EINTR;
+ return ret;
+}
+

- if (timeout) {
- if (compat_get_timespec64(&t, timeout))
+struct __compat_aio_sigset {
+ compat_sigset_t __user *sigmask;
+ compat_size_t sigsetsize;
+};
+
+COMPAT_SYSCALL_DEFINE6(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)
+{
+ struct __compat_aio_sigset ksig = { NULL, };
+ sigset_t ksigmask, sigsaved;
+ struct timespec64 t;
+ int ret;
+
+ if (timeout && compat_get_timespec64(&t, timeout))
+ return -EFAULT;
+
+ if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
+ return -EFAULT;
+
+ if (ksig.sigmask) {
+ if (ksig.sigsetsize != sizeof(compat_sigset_t))
+ return -EINVAL;
+ if (get_compat_sigset(&ksigmask, ksig.sigmask))
return -EFAULT;
+ sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
+ sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+ }

+ ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
+ if (signal_pending(current)) {
+ if (ksig.sigmask) {
+ current->saved_sigmask = sigsaved;
+ set_restore_sigmask();
+ }
+ if (!ret)
+ ret = -ERESTARTNOHAND;
+ } else {
+ if (ksig.sigmask)
+ sigprocmask(SIG_SETMASK, &sigsaved, NULL);
}

- return do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
+ return ret;
}
#endif
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,
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 8bcb186c6f67..42990676a55e 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -732,9 +732,11 @@ __SYSCALL(__NR_pkey_alloc, sys_pkey_alloc)
__SYSCALL(__NR_pkey_free, sys_pkey_free)
#define __NR_statx 291
__SYSCALL(__NR_statx, sys_statx)
+#define __NR_io_pgetevents 292
+__SC_COMP(__NR_io_pgetevents, sys_io_pgetevents, compat_sys_io_pgetevents)

#undef __NR_syscalls
-#define __NR_syscalls 292
+#define __NR_syscalls 293

/*
* 32 bit systems traditionally used different
diff --git a/include/uapi/linux/aio_abi.h b/include/uapi/linux/aio_abi.h
index a04adbc70ddf..2c0a3415beee 100644
--- a/include/uapi/linux/aio_abi.h
+++ b/include/uapi/linux/aio_abi.h
@@ -29,6 +29,7 @@

#include <linux/types.h>
#include <linux/fs.h>
+#include <linux/signal.h>
#include <asm/byteorder.h>

typedef __kernel_ulong_t aio_context_t;
@@ -108,5 +109,10 @@ struct iocb {
#undef IFBIG
#undef IFLITTLE

+struct __aio_sigset {
+ sigset_t __user *sigmask;
+ size_t sigsetsize;
+};
+
#endif /* __LINUX__AIO_ABI_H */

diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 9791364925dc..183169c2a75b 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -43,7 +43,9 @@ COND_SYSCALL(io_submit);
COND_SYSCALL_COMPAT(io_submit);
COND_SYSCALL(io_cancel);
COND_SYSCALL(io_getevents);
+COND_SYSCALL(io_pgetevents);
COND_SYSCALL_COMPAT(io_getevents);
+COND_SYSCALL_COMPAT(io_pgetevents);

/* fs/xattr.c */

--
2.17.0

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