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io_uring: add notification slot registration

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Let the userspace to register and unregister notification slots.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a0aa8161fe3ebb2a4cc6e5dbd0cffb96e6881cf5.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2022-07-12 21:52:42 +01:00 committed by Jens Axboe
parent 68ef5578ef
commit bc24d6bd32
4 changed files with 72 additions and 0 deletions
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17
include/uapi/linux/io_uring.h
View file

@ -457,6 +457,10 @@ 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
};
@ -503,6 +507,19 @@ 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)

9
io_uring/io_uring.c
View file

@ -3870,6 +3870,15 @@ 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;

43
io_uring/notif.c
View file

@ -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;
}

3
io_uring/notif.h
View file

@ -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);