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WSL2-Linux-Kernel
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io_uring: allocate the two rings together 

Both the sq and the cq rings have sizes just over a power of two, and
the sq ring is significantly smaller. By bundling them in a single
alllocation, we get the sq ring for free.

This also means that IORING_OFF_SQ_RING and IORING_OFF_CQ_RING now mean
the same thing. If we indicate this to userspace, we can save a mmap
call.

Signed-off-by: Hristo Venev <hristo@venev.name>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Hristo Venev 2019-08-26 17:23:46 +00:00 коммит произвёл Jens Axboe
Родитель 27c4d3a325
Коммит 75b28affdd
1 изменённых файлов: 128 добавлений и 127 удалений
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255
fs/io_uring.c
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@ -84,27 +84,29 @@ struct io_uring {
}; };
/* /*
* This data is shared with the application through the mmap at offset * This data is shared with the application through the mmap at offsets
* IORING_OFF_SQ_RING. * IORING_OFF_SQ_RING and IORING_OFF_CQ_RING.
* *
* The offsets to the member fields are published through struct * The offsets to the member fields are published through struct
* io_sqring_offsets when calling io_uring_setup. * io_sqring_offsets when calling io_uring_setup.
*/ */
struct io_sq_ring { struct io_rings {
/* /*
* Head and tail offsets into the ring; the offsets need to be * Head and tail offsets into the ring; the offsets need to be
* masked to get valid indices. * masked to get valid indices.
* *
* The kernel controls head and the application controls tail. * The kernel controls head of the sq ring and the tail of the cq ring,
* and the application controls tail of the sq ring and the head of the
* cq ring.
*/ */
struct io_uring r; struct io_uring sq, cq;
/* /*
* Bitmask to apply to head and tail offsets (constant, equals * Bitmasks to apply to head and tail offsets (constant, equals
* ring_entries - 1) * ring_entries - 1)
*/ */
u32 ring_mask; u32 sq_ring_mask, cq_ring_mask;
/* Ring size (constant, power of 2) */ /* Ring sizes (constant, power of 2) */
u32 ring_entries; u32 sq_ring_entries, cq_ring_entries;
/* /*
* Number of invalid entries dropped by the kernel due to * Number of invalid entries dropped by the kernel due to
* invalid index stored in array * invalid index stored in array
@ -117,7 +119,7 @@ struct io_sq_ring {
* counter includes all submissions that were dropped reaching * counter includes all submissions that were dropped reaching
* the new SQ head (and possibly more). * the new SQ head (and possibly more).
*/ */
u32 dropped; u32 sq_dropped;
/* /*
* Runtime flags * Runtime flags
* *
@ -127,43 +129,7 @@ struct io_sq_ring {
* The application needs a full memory barrier before checking * The application needs a full memory barrier before checking
* for IORING_SQ_NEED_WAKEUP after updating the sq tail. * for IORING_SQ_NEED_WAKEUP after updating the sq tail.
*/ */
u32 flags; u32 sq_flags;
/*
* Ring buffer of indices into array of io_uring_sqe, which is
* mmapped by the application using the IORING_OFF_SQES offset.
*
* This indirection could e.g. be used to assign fixed
* io_uring_sqe entries to operations and only submit them to
* the queue when needed.
*
* The kernel modifies neither the indices array nor the entries
* array.
*/
u32 array[];
};
/*
* This data is shared with the application through the mmap at offset
* IORING_OFF_CQ_RING.
*
* The offsets to the member fields are published through struct
* io_cqring_offsets when calling io_uring_setup.
*/
struct io_cq_ring {
/*
* Head and tail offsets into the ring; the offsets need to be
* masked to get valid indices.
*
* The application controls head and the kernel tail.
*/
struct io_uring r;
/*
* Bitmask to apply to head and tail offsets (constant, equals
* ring_entries - 1)
*/
u32 ring_mask;
/* Ring size (constant, power of 2) */
u32 ring_entries;
/* /*
* Number of completion events lost because the queue was full; * Number of completion events lost because the queue was full;
* this should be avoided by the application by making sure * this should be avoided by the application by making sure
@ -177,7 +143,7 @@ struct io_cq_ring {
* As completion events come in out of order this counter is not * As completion events come in out of order this counter is not
* ordered with any other data. * ordered with any other data.
*/ */
u32 overflow; u32 cq_overflow;
/* /*
* Ring buffer of completion events. * Ring buffer of completion events.
* *
@ -185,7 +151,7 @@ struct io_cq_ring {
* produced, so the application is allowed to modify pending * produced, so the application is allowed to modify pending
* entries. * entries.
*/ */
struct io_uring_cqe cqes[]; struct io_uring_cqe cqes[] ____cacheline_aligned_in_smp;
}; };
struct io_mapped_ubuf { struct io_mapped_ubuf {
@ -215,8 +181,18 @@ struct io_ring_ctx {
bool compat; bool compat;
bool account_mem; bool account_mem;
/* SQ ring */ /*
struct io_sq_ring *sq_ring; * Ring buffer of indices into array of io_uring_sqe, which is
* mmapped by the application using the IORING_OFF_SQES offset.
*
* This indirection could e.g. be used to assign fixed
* io_uring_sqe entries to operations and only submit them to
* the queue when needed.
*
* The kernel modifies neither the indices array nor the entries
* array.
*/
u32 *sq_array;
unsigned cached_sq_head; unsigned cached_sq_head;
unsigned sq_entries; unsigned sq_entries;
unsigned sq_mask; unsigned sq_mask;
@ -234,8 +210,6 @@ struct io_ring_ctx {
struct completion sqo_thread_started; struct completion sqo_thread_started;
struct { struct {
/* CQ ring */
struct io_cq_ring *cq_ring;
unsigned cached_cq_tail; unsigned cached_cq_tail;
unsigned cq_entries; unsigned cq_entries;
unsigned cq_mask; unsigned cq_mask;
@ -244,6 +218,8 @@ struct io_ring_ctx {
struct eventfd_ctx *cq_ev_fd; struct eventfd_ctx *cq_ev_fd;
} ____cacheline_aligned_in_smp; } ____cacheline_aligned_in_smp;
struct io_rings *rings;
/* /*
* If used, fixed file set. Writers must ensure that ->refs is dead, * If used, fixed file set. Writers must ensure that ->refs is dead,
* readers must ensure that ->refs is alive as long as the file* is * readers must ensure that ->refs is alive as long as the file* is
@ -430,7 +406,7 @@ static inline bool io_sequence_defer(struct io_ring_ctx *ctx,
if ((req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN) if ((req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN)
return false; return false;
return req->sequence != ctx->cached_cq_tail + ctx->sq_ring->dropped; return req->sequence != ctx->cached_cq_tail + ctx->rings->sq_dropped;
} }
static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx) static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx)
@ -451,11 +427,11 @@ static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx)
static void __io_commit_cqring(struct io_ring_ctx *ctx) static void __io_commit_cqring(struct io_ring_ctx *ctx)
{ {
struct io_cq_ring *ring = ctx->cq_ring; struct io_rings *rings = ctx->rings;
if (ctx->cached_cq_tail != READ_ONCE(ring->r.tail)) { if (ctx->cached_cq_tail != READ_ONCE(rings->cq.tail)) {
/* order cqe stores with ring update */ /* order cqe stores with ring update */
smp_store_release(&ring->r.tail, ctx->cached_cq_tail); smp_store_release(&rings->cq.tail, ctx->cached_cq_tail);
if (wq_has_sleeper(&ctx->cq_wait)) { if (wq_has_sleeper(&ctx->cq_wait)) {
wake_up_interruptible(&ctx->cq_wait); wake_up_interruptible(&ctx->cq_wait);
@ -478,7 +454,7 @@ static void io_commit_cqring(struct io_ring_ctx *ctx)
static struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx) static struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
{ {
struct io_cq_ring *ring = ctx->cq_ring; struct io_rings *rings = ctx->rings;
unsigned tail; unsigned tail;
tail = ctx->cached_cq_tail; tail = ctx->cached_cq_tail;
@ -487,11 +463,11 @@ static struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
* control dependency is enough as we're using WRITE_ONCE to * control dependency is enough as we're using WRITE_ONCE to
* fill the cq entry * fill the cq entry
*/ */
if (tail - READ_ONCE(ring->r.head) == ring->ring_entries) if (tail - READ_ONCE(rings->cq.head) == rings->cq_ring_entries)
return NULL; return NULL;
ctx->cached_cq_tail++; ctx->cached_cq_tail++;
return &ring->cqes[tail & ctx->cq_mask]; return &rings->cqes[tail & ctx->cq_mask];
} }
static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data, static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data,
@ -510,9 +486,9 @@ static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data,
WRITE_ONCE(cqe->res, res); WRITE_ONCE(cqe->res, res);
WRITE_ONCE(cqe->flags, 0); WRITE_ONCE(cqe->flags, 0);
} else { } else {
unsigned overflow = READ_ONCE(ctx->cq_ring->overflow); unsigned overflow = READ_ONCE(ctx->rings->cq_overflow);
WRITE_ONCE(ctx->cq_ring->overflow, overflow + 1); WRITE_ONCE(ctx->rings->cq_overflow, overflow + 1);
} }
} }
@ -679,11 +655,11 @@ static void io_put_req(struct io_kiocb *req)
io_free_req(req); io_free_req(req);
} }
static unsigned io_cqring_events(struct io_cq_ring *ring) static unsigned io_cqring_events(struct io_rings *rings)
{ {
/* See comment at the top of this file */ /* See comment at the top of this file */
smp_rmb(); smp_rmb();
return READ_ONCE(ring->r.tail) - READ_ONCE(ring->r.head); return READ_ONCE(rings->cq.tail) - READ_ONCE(rings->cq.head);
} }
/* /*
@ -836,7 +812,7 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, unsigned *nr_events,
* If we do, we can potentially be spinning for commands that * If we do, we can potentially be spinning for commands that
* already triggered a CQE (eg in error). * already triggered a CQE (eg in error).
*/ */
if (io_cqring_events(ctx->cq_ring)) if (io_cqring_events(ctx->rings))
break; break;
/* /*
@ -2205,15 +2181,15 @@ static void io_submit_state_start(struct io_submit_state *state,
static void io_commit_sqring(struct io_ring_ctx *ctx) static void io_commit_sqring(struct io_ring_ctx *ctx)
{ {
struct io_sq_ring *ring = ctx->sq_ring; struct io_rings *rings = ctx->rings;
if (ctx->cached_sq_head != READ_ONCE(ring->r.head)) { if (ctx->cached_sq_head != READ_ONCE(rings->sq.head)) {
/* /*
* Ensure any loads from the SQEs are done at this point, * Ensure any loads from the SQEs are done at this point,
* since once we write the new head, the application could * since once we write the new head, the application could
* write new data to them. * write new data to them.
*/ */
smp_store_release(&ring->r.head, ctx->cached_sq_head); smp_store_release(&rings->sq.head, ctx->cached_sq_head);
} }
} }
@ -2227,7 +2203,8 @@ static void io_commit_sqring(struct io_ring_ctx *ctx)
*/ */
static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s) static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
{ {
struct io_sq_ring *ring = ctx->sq_ring; struct io_rings *rings = ctx->rings;
u32 *sq_array = ctx->sq_array;
unsigned head; unsigned head;
/* /*
@ -2240,10 +2217,10 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
*/ */
head = ctx->cached_sq_head; head = ctx->cached_sq_head;
/* make sure SQ entry isn't read before tail */ /* make sure SQ entry isn't read before tail */
if (head == smp_load_acquire(&ring->r.tail)) if (head == smp_load_acquire(&rings->sq.tail))
return false; return false;
head = READ_ONCE(ring->array[head & ctx->sq_mask]); head = READ_ONCE(sq_array[head & ctx->sq_mask]);
if (head < ctx->sq_entries) { if (head < ctx->sq_entries) {
s->index = head; s->index = head;
s->sqe = &ctx->sq_sqes[head]; s->sqe = &ctx->sq_sqes[head];
@ -2253,7 +2230,7 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
/* drop invalid entries */ /* drop invalid entries */
ctx->cached_sq_head++; ctx->cached_sq_head++;
ring->dropped++; rings->sq_dropped++;
return false; return false;
} }
@ -2366,7 +2343,7 @@ static int io_sq_thread(void *data)
TASK_INTERRUPTIBLE); TASK_INTERRUPTIBLE);
/* Tell userspace we may need a wakeup call */ /* Tell userspace we may need a wakeup call */
ctx->sq_ring->flags |= IORING_SQ_NEED_WAKEUP; ctx->rings->sq_flags |= IORING_SQ_NEED_WAKEUP;
/* make sure to read SQ tail after writing flags */ /* make sure to read SQ tail after writing flags */
smp_mb(); smp_mb();
@ -2380,12 +2357,12 @@ static int io_sq_thread(void *data)
schedule(); schedule();
finish_wait(&ctx->sqo_wait, &wait); finish_wait(&ctx->sqo_wait, &wait);
ctx->sq_ring->flags &= ~IORING_SQ_NEED_WAKEUP; ctx->rings->sq_flags &= ~IORING_SQ_NEED_WAKEUP;
continue; continue;
} }
finish_wait(&ctx->sqo_wait, &wait); finish_wait(&ctx->sqo_wait, &wait);
ctx->sq_ring->flags &= ~IORING_SQ_NEED_WAKEUP; ctx->rings->sq_flags &= ~IORING_SQ_NEED_WAKEUP;
} }
i = 0; i = 0;
@ -2477,10 +2454,10 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
const sigset_t __user *sig, size_t sigsz) const sigset_t __user *sig, size_t sigsz)
{ {
struct io_cq_ring *ring = ctx->cq_ring; struct io_rings *rings = ctx->rings;
int ret; int ret;
if (io_cqring_events(ring) >= min_events) if (io_cqring_events(rings) >= min_events)
return 0; return 0;
if (sig) { if (sig) {
@ -2496,12 +2473,12 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
return ret; return ret;
} }
ret = wait_event_interruptible(ctx->wait, io_cqring_events(ring) >= min_events); ret = wait_event_interruptible(ctx->wait, io_cqring_events(rings) >= min_events);
restore_saved_sigmask_unless(ret == -ERESTARTSYS); restore_saved_sigmask_unless(ret == -ERESTARTSYS);
if (ret == -ERESTARTSYS) if (ret == -ERESTARTSYS)
ret = -EINTR; ret = -EINTR;
return READ_ONCE(ring->r.head) == READ_ONCE(ring->r.tail) ? ret : 0; return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
} }
static void __io_sqe_files_unregister(struct io_ring_ctx *ctx) static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
@ -2821,17 +2798,45 @@ static void *io_mem_alloc(size_t size)
return (void *) __get_free_pages(gfp_flags, get_order(size)); return (void *) __get_free_pages(gfp_flags, get_order(size));
} }
static unsigned long rings_size(unsigned sq_entries, unsigned cq_entries,
size_t *sq_offset)
{
struct io_rings *rings;
size_t off, sq_array_size;
off = struct_size(rings, cqes, cq_entries);
if (off == SIZE_MAX)
return SIZE_MAX;
#ifdef CONFIG_SMP
off = ALIGN(off, SMP_CACHE_BYTES);
if (off == 0)
return SIZE_MAX;
#endif
sq_array_size = array_size(sizeof(u32), sq_entries);
if (sq_array_size == SIZE_MAX)
return SIZE_MAX;
if (check_add_overflow(off, sq_array_size, &off))
return SIZE_MAX;
if (sq_offset)
*sq_offset = off;
return off;
}
static unsigned long ring_pages(unsigned sq_entries, unsigned cq_entries) static unsigned long ring_pages(unsigned sq_entries, unsigned cq_entries)
{ {
struct io_sq_ring *sq_ring; size_t pages;
struct io_cq_ring *cq_ring;
size_t bytes;
bytes = struct_size(sq_ring, array, sq_entries); pages = (size_t)1 << get_order(
bytes += array_size(sizeof(struct io_uring_sqe), sq_entries); rings_size(sq_entries, cq_entries, NULL));
bytes += struct_size(cq_ring, cqes, cq_entries); pages += (size_t)1 << get_order(
array_size(sizeof(struct io_uring_sqe), sq_entries));
return (bytes + PAGE_SIZE - 1) / PAGE_SIZE; return pages;
} }
static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx) static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
@ -3076,9 +3081,8 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
} }
#endif #endif
io_mem_free(ctx->sq_ring); io_mem_free(ctx->rings);
io_mem_free(ctx->sq_sqes); io_mem_free(ctx->sq_sqes);
io_mem_free(ctx->cq_ring);
percpu_ref_exit(&ctx->refs); percpu_ref_exit(&ctx->refs);
if (ctx->account_mem) if (ctx->account_mem)
@ -3099,10 +3103,10 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait)
* io_commit_cqring * io_commit_cqring
*/ */
smp_rmb(); smp_rmb();
if (READ_ONCE(ctx->sq_ring->r.tail) - ctx->cached_sq_head != if (READ_ONCE(ctx->rings->sq.tail) - ctx->cached_sq_head !=
ctx->sq_ring->ring_entries) ctx->rings->sq_ring_entries)
mask |= EPOLLOUT | EPOLLWRNORM; mask |= EPOLLOUT | EPOLLWRNORM;
if (READ_ONCE(ctx->cq_ring->r.head) != ctx->cached_cq_tail) if (READ_ONCE(ctx->rings->sq.head) != ctx->cached_cq_tail)
mask |= EPOLLIN | EPOLLRDNORM; mask |= EPOLLIN | EPOLLRDNORM;
return mask; return mask;
@ -3147,14 +3151,12 @@ static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
switch (offset) { switch (offset) {
case IORING_OFF_SQ_RING: case IORING_OFF_SQ_RING:
ptr = ctx->sq_ring; case IORING_OFF_CQ_RING:
ptr = ctx->rings;
break; break;
case IORING_OFF_SQES: case IORING_OFF_SQES:
ptr = ctx->sq_sqes; ptr = ctx->sq_sqes;
break; break;
case IORING_OFF_CQ_RING:
ptr = ctx->cq_ring;
break;
default: default:
return -EINVAL; return -EINVAL;
} }
@ -3241,19 +3243,27 @@ static const struct file_operations io_uring_fops = {
static int io_allocate_scq_urings(struct io_ring_ctx *ctx, static int io_allocate_scq_urings(struct io_ring_ctx *ctx,
struct io_uring_params *p) struct io_uring_params *p)
{ {
struct io_sq_ring *sq_ring; struct io_rings *rings;
struct io_cq_ring *cq_ring; size_t size, sq_array_offset;
size_t size;
sq_ring = io_mem_alloc(struct_size(sq_ring, array, p->sq_entries)); size = rings_size(p->sq_entries, p->cq_entries, &sq_array_offset);
if (!sq_ring) if (size == SIZE_MAX)
return -EOVERFLOW;
rings = io_mem_alloc(size);
if (!rings)
return -ENOMEM; return -ENOMEM;
ctx->sq_ring = sq_ring; ctx->rings = rings;
sq_ring->ring_mask = p->sq_entries - 1; ctx->sq_array = (u32 *)((char *)rings + sq_array_offset);
sq_ring->ring_entries = p->sq_entries; rings->sq_ring_mask = p->sq_entries - 1;
ctx->sq_mask = sq_ring->ring_mask; rings->cq_ring_mask = p->cq_entries - 1;
ctx->sq_entries = sq_ring->ring_entries; rings->sq_ring_entries = p->sq_entries;
rings->cq_ring_entries = p->cq_entries;
ctx->sq_mask = rings->sq_ring_mask;
ctx->cq_mask = rings->cq_ring_mask;
ctx->sq_entries = rings->sq_ring_entries;
ctx->cq_entries = rings->cq_ring_entries;
size = array_size(sizeof(struct io_uring_sqe), p->sq_entries); size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
if (size == SIZE_MAX) if (size == SIZE_MAX)
@ -3263,15 +3273,6 @@ static int io_allocate_scq_urings(struct io_ring_ctx *ctx,
if (!ctx->sq_sqes) if (!ctx->sq_sqes)
return -ENOMEM; return -ENOMEM;
cq_ring = io_mem_alloc(struct_size(cq_ring, cqes, p->cq_entries));
if (!cq_ring)
return -ENOMEM;
ctx->cq_ring = cq_ring;
cq_ring->ring_mask = p->cq_entries - 1;
cq_ring->ring_entries = p->cq_entries;
ctx->cq_mask = cq_ring->ring_mask;
ctx->cq_entries = cq_ring->ring_entries;
return 0; return 0;
} }
@ -3375,21 +3376,21 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p)
goto err; goto err;
memset(&p->sq_off, 0, sizeof(p->sq_off)); memset(&p->sq_off, 0, sizeof(p->sq_off));
p->sq_off.head = offsetof(struct io_sq_ring, r.head); p->sq_off.head = offsetof(struct io_rings, sq.head);
p->sq_off.tail = offsetof(struct io_sq_ring, r.tail); p->sq_off.tail = offsetof(struct io_rings, sq.tail);
p->sq_off.ring_mask = offsetof(struct io_sq_ring, ring_mask); p->sq_off.ring_mask = offsetof(struct io_rings, sq_ring_mask);
p->sq_off.ring_entries = offsetof(struct io_sq_ring, ring_entries); p->sq_off.ring_entries = offsetof(struct io_rings, sq_ring_entries);
p->sq_off.flags = offsetof(struct io_sq_ring, flags); p->sq_off.flags = offsetof(struct io_rings, sq_flags);
p->sq_off.dropped = offsetof(struct io_sq_ring, dropped); p->sq_off.dropped = offsetof(struct io_rings, sq_dropped);
p->sq_off.array = offsetof(struct io_sq_ring, array); p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
memset(&p->cq_off, 0, sizeof(p->cq_off)); memset(&p->cq_off, 0, sizeof(p->cq_off));
p->cq_off.head = offsetof(struct io_cq_ring, r.head); p->cq_off.head = offsetof(struct io_rings, cq.head);
p->cq_off.tail = offsetof(struct io_cq_ring, r.tail); p->cq_off.tail = offsetof(struct io_rings, cq.tail);
p->cq_off.ring_mask = offsetof(struct io_cq_ring, ring_mask); p->cq_off.ring_mask = offsetof(struct io_rings, cq_ring_mask);
p->cq_off.ring_entries = offsetof(struct io_cq_ring, ring_entries); p->cq_off.ring_entries = offsetof(struct io_rings, cq_ring_entries);
p->cq_off.overflow = offsetof(struct io_cq_ring, overflow); p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);
p->cq_off.cqes = offsetof(struct io_cq_ring, cqes); p->cq_off.cqes = offsetof(struct io_rings, cqes);
return ret; return ret;
err: err:
io_ring_ctx_wait_and_kill(ctx); io_ring_ctx_wait_and_kill(ctx);