In scenarios where a high frequency of wait events are seen, the copy
of the struct io_uring_getevents_arg is quite noticeable in the
profiles in terms of time spent. It can be seen as up to 3.5-4.5%.
Rewrite the copy-in logic, saving about 0.5% of the time.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
---
io_uring/io_uring.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 8952453ea807..612e7d66f845 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3239,6 +3239,7 @@ static int io_validate_ext_arg(unsigned flags, const void __user *argp, size_t a
static int io_get_ext_arg(unsigned flags, const void __user *argp,
struct ext_arg *ext_arg)
{
+ const struct io_uring_getevents_arg __user *uarg = argp;
struct io_uring_getevents_arg arg;
/*
@@ -3256,8 +3257,13 @@ static int io_get_ext_arg(unsigned flags, const void __user *argp,
*/
if (ext_arg->argsz != sizeof(arg))
return -EINVAL;
- if (copy_from_user(&arg, argp, sizeof(arg)))
+ if (!user_access_begin(uarg, sizeof(*uarg)))
return -EFAULT;
+ unsafe_get_user(arg.sigmask, &uarg->sigmask, uaccess_end);
+ unsafe_get_user(arg.min_wait_usec, &uarg->min_wait_usec, uaccess_end);
+ unsafe_get_user(arg.ts, &uarg->ts, uaccess_end);
+ unsafe_get_user(arg.sigmask_sz, &uarg->sigmask_sz, uaccess_end);
+ user_access_end();
ext_arg->min_time = arg.min_wait_usec * NSEC_PER_USEC;
ext_arg->sig = u64_to_user_ptr(arg.sigmask);
ext_arg->argsz = arg.sigmask_sz;
@@ -3267,6 +3273,9 @@ static int io_get_ext_arg(unsigned flags, const void __user *argp,
ext_arg->ts_set = true;
}
return 0;
+uaccess_end:
+ user_access_end();
+ return -EFAULT;
}
SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
--
2.45.2
