[PATCH net-next v4 18/27] io_uring: add notification slot registration

Pavel Begunkov
2022-07-07T11:52:59Z

Let the userspace to register and unregister notification slots.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
include/uapi/linux/io_uring.h | 17 ++++++++++++++
io_uring/io_uring.c | 9 ++++++++
io_uring/notif.c | 43 +++++++++++++++++++++++++++++++++++
io_uring/notif.h | 3 +++
4 files changed, 72 insertions(+)

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index e858dba2e6c9..f1ba8e934168 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -454,6 +454,10 @@ enum {
/* register a range of fixed file slots for automatic slot allocation */
IORING_REGISTER_FILE_ALLOC_RANGE = 25,

+ /* zerocopy notification API */
+ IORING_REGISTER_NOTIFIERS = 26,
+ IORING_UNREGISTER_NOTIFIERS = 27,
+
/* this goes last */
IORING_REGISTER_LAST
};
@@ -500,6 +504,19 @@ struct io_uring_rsrc_update2 {
__u32 resv2;
};

+struct io_uring_notification_slot {
+ __u64 tag;
+ __u64 resv[3];
+};
+
+struct io_uring_notification_register {
+ __u32 nr_slots;
+ __u32 resv;
+ __u64 resv2;
+ __u64 data;
+ __u64 resv3;
+};
+
/* Skip updating fd indexes set to this value in the fd table */
#define IORING_REGISTER_FILES_SKIP (-2)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index bdc5a2839d94..41ef98a43d32 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -3875,6 +3875,15 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
break;
ret = io_register_file_alloc_range(ctx, arg);
break;
+ case IORING_REGISTER_NOTIFIERS:
+ ret = io_notif_register(ctx, arg, nr_args);
+ break;
+ case IORING_UNREGISTER_NOTIFIERS:
+ ret = -EINVAL;
+ if (arg || nr_args)
+ break;
+ ret = io_notif_unregister(ctx);
+ break;
default:
ret = -EINVAL;
break;
diff --git a/io_uring/notif.c b/io_uring/notif.c
index 0a2e98bd74f6..e6d98dc208c7 100644
--- a/io_uring/notif.c
+++ b/io_uring/notif.c
@@ -162,5 +162,48 @@ __cold int io_notif_unregister(struct io_ring_ctx *ctx)
kvfree(ctx->notif_slots);
ctx->notif_slots = NULL;
ctx->nr_notif_slots = 0;
+ io_notif_cache_purge(ctx);
+ return 0;
+}
+
+__cold int io_notif_register(struct io_ring_ctx *ctx,
+ void __user *arg, unsigned int size)
+ __must_hold(&ctx->uring_lock)
+{
+ struct io_uring_notification_slot __user *slots;
+ struct io_uring_notification_slot slot;
+ struct io_uring_notification_register reg;
+ unsigned i;
+
+ if (ctx->nr_notif_slots)
+ return -EBUSY;
+ if (size != sizeof(reg))
+ return -EINVAL;
+ if (copy_from_user(&reg, arg, sizeof(reg)))
+ return -EFAULT;
+ if (!reg.nr_slots || reg.nr_slots > IORING_MAX_NOTIF_SLOTS)
+ return -EINVAL;
+ if (reg.resv || reg.resv2 || reg.resv3)
+ return -EINVAL;
+
+ slots = u64_to_user_ptr(reg.data);
+ ctx->notif_slots = kvcalloc(reg.nr_slots, sizeof(ctx->notif_slots[0]),
+ GFP_KERNEL_ACCOUNT);
+ if (!ctx->notif_slots)
+ return -ENOMEM;
+
+ for (i = 0; i < reg.nr_slots; i++, ctx->nr_notif_slots++) {
+ struct io_notif_slot *notif_slot = &ctx->notif_slots[i];
+
+ if (copy_from_user(&slot, &slots[i], sizeof(slot))) {
+ io_notif_unregister(ctx);
+ return -EFAULT;
+ }
+ if (slot.resv[0] | slot.resv[1] | slot.resv[2]) {
+ io_notif_unregister(ctx);
+ return -EINVAL;
+ }
+ notif_slot->tag = slot.tag;
+ }
return 0;
}
diff --git a/io_uring/notif.h b/io_uring/notif.h
index 1dd48efb7744..00efe164bdc4 100644
--- a/io_uring/notif.h
+++ b/io_uring/notif.h
@@ -6,6 +6,7 @@
#include <linux/nospec.h>

#define IO_NOTIF_SPLICE_BATCH 32
+#define IORING_MAX_NOTIF_SLOTS (1U << 10)

struct io_notif {
struct ubuf_info uarg;
@@ -48,6 +49,8 @@ struct io_notif_slot {
u32 seq;
};

+int io_notif_register(struct io_ring_ctx *ctx,
+ void __user *arg, unsigned int size);
int io_notif_unregister(struct io_ring_ctx *ctx);
void io_notif_cache_purge(struct io_ring_ctx *ctx);

--
2.36.1