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io_uring: move SQPOLL related handling into its own file

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Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2022-05-25 09:13:39 -06:00
parent 59915143e8
commit 17437f3114
5 changed files with 497 additions and 462 deletions
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3
io_uring/Makefile
View File

@ -5,5 +5,6 @@
obj-$(CONFIG_IO_URING) += io_uring.o xattr.o nop.o fs.o splice.o \ obj-$(CONFIG_IO_URING) += io_uring.o xattr.o nop.o fs.o splice.o \
sync.o advise.o filetable.o \ sync.o advise.o filetable.o \
openclose.o uring_cmd.o epoll.o \ openclose.o uring_cmd.o epoll.o \
statx.o net.o msg_ring.o timeout.o statx.o net.o msg_ring.o timeout.o \
sqpoll.o
obj-$(CONFIG_IO_WQ) += io-wq.o obj-$(CONFIG_IO_WQ) += io-wq.o

467
io_uring/io_uring.c
View File

@ -92,6 +92,7 @@
#include "io_uring_types.h" #include "io_uring_types.h"
#include "io_uring.h" #include "io_uring.h"
#include "refs.h" #include "refs.h"
#include "sqpoll.h"
#include "xattr.h" #include "xattr.h"
#include "nop.h" #include "nop.h"
@ -109,7 +110,6 @@
#define IORING_MAX_ENTRIES 32768 #define IORING_MAX_ENTRIES 32768
#define IORING_MAX_CQ_ENTRIES (2 * IORING_MAX_ENTRIES) #define IORING_MAX_CQ_ENTRIES (2 * IORING_MAX_ENTRIES)
#define IORING_SQPOLL_CAP_ENTRIES_VALUE 8
/* only define max */ /* only define max */
#define IORING_MAX_FIXED_FILES (1U << 20) #define IORING_MAX_FIXED_FILES (1U << 20)
@ -214,31 +214,6 @@ struct io_buffer {
__u16 bgid; __u16 bgid;
}; };
enum {
IO_SQ_THREAD_SHOULD_STOP = 0,
IO_SQ_THREAD_SHOULD_PARK,
};
struct io_sq_data {
refcount_t refs;
atomic_t park_pending;
struct mutex lock;
/* ctx's that are using this sqd */
struct list_head ctx_list;
struct task_struct *thread;
struct wait_queue_head wait;
unsigned sq_thread_idle;
int sq_cpu;
pid_t task_pid;
pid_t task_tgid;
unsigned long state;
struct completion exited;
};
#define IO_COMPL_BATCH 32 #define IO_COMPL_BATCH 32
#define IO_REQ_CACHE_SIZE 32 #define IO_REQ_CACHE_SIZE 32
#define IO_REQ_ALLOC_BATCH 8 #define IO_REQ_ALLOC_BATCH 8
@ -402,7 +377,6 @@ static void io_uring_del_tctx_node(unsigned long index);
static void io_uring_try_cancel_requests(struct io_ring_ctx *ctx, static void io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
struct task_struct *task, struct task_struct *task,
bool cancel_all); bool cancel_all);
static void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd);
static void io_dismantle_req(struct io_kiocb *req); static void io_dismantle_req(struct io_kiocb *req);
static int __io_register_rsrc_update(struct io_ring_ctx *ctx, unsigned type, static int __io_register_rsrc_update(struct io_ring_ctx *ctx, unsigned type,
@ -1079,13 +1053,6 @@ static void __io_commit_cqring_flush(struct io_ring_ctx *ctx)
io_eventfd_signal(ctx); io_eventfd_signal(ctx);
} }
static inline bool io_sqring_full(struct io_ring_ctx *ctx)
{
struct io_rings *r = ctx->rings;
return READ_ONCE(r->sq.tail) - ctx->cached_sq_head == ctx->sq_entries;
}
static inline unsigned int __io_cqring_events(struct io_ring_ctx *ctx) static inline unsigned int __io_cqring_events(struct io_ring_ctx *ctx)
{ {
return ctx->cached_cq_tail - READ_ONCE(ctx->rings->cq.head); return ctx->cached_cq_tail - READ_ONCE(ctx->rings->cq.head);
@ -1974,28 +1941,7 @@ static unsigned io_cqring_events(struct io_ring_ctx *ctx)
return __io_cqring_events(ctx); return __io_cqring_events(ctx);
} }
static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx) int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
{
struct io_rings *rings = ctx->rings;
/* make sure SQ entry isn't read before tail */
return smp_load_acquire(&rings->sq.tail) - ctx->cached_sq_head;
}
static inline bool io_run_task_work(void)
{
if (test_thread_flag(TIF_NOTIFY_SIGNAL) || task_work_pending(current)) {
__set_current_state(TASK_RUNNING);
clear_notify_signal();
if (task_work_pending(current))
task_work_run();
return true;
}
return false;
}
static int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
{ {
struct io_wq_work_node *pos, *start, *prev; struct io_wq_work_node *pos, *start, *prev;
unsigned int poll_flags = BLK_POLL_NOSLEEP; unsigned int poll_flags = BLK_POLL_NOSLEEP;
@ -5297,7 +5243,7 @@ static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
return NULL; return NULL;
} }
static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr) int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
__must_hold(&ctx->uring_lock) __must_hold(&ctx->uring_lock)
{ {
unsigned int entries = io_sqring_entries(ctx); unsigned int entries = io_sqring_entries(ctx);
@ -5349,173 +5295,6 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
return ret; return ret;
} }
static inline bool io_sqd_events_pending(struct io_sq_data *sqd)
{
return READ_ONCE(sqd->state);
}
static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
{
unsigned int to_submit;
int ret = 0;
to_submit = io_sqring_entries(ctx);
/* if we're handling multiple rings, cap submit size for fairness */
if (cap_entries && to_submit > IORING_SQPOLL_CAP_ENTRIES_VALUE)
to_submit = IORING_SQPOLL_CAP_ENTRIES_VALUE;
if (!wq_list_empty(&ctx->iopoll_list) || to_submit) {
const struct cred *creds = NULL;
if (ctx->sq_creds != current_cred())
creds = override_creds(ctx->sq_creds);
mutex_lock(&ctx->uring_lock);
if (!wq_list_empty(&ctx->iopoll_list))
io_do_iopoll(ctx, true);
/*
* Don't submit if refs are dying, good for io_uring_register(),
* but also it is relied upon by io_ring_exit_work()
*/
if (to_submit && likely(!percpu_ref_is_dying(&ctx->refs)) &&
!(ctx->flags & IORING_SETUP_R_DISABLED))
ret = io_submit_sqes(ctx, to_submit);
mutex_unlock(&ctx->uring_lock);
if (to_submit && wq_has_sleeper(&ctx->sqo_sq_wait))
wake_up(&ctx->sqo_sq_wait);
if (creds)
revert_creds(creds);
}
return ret;
}
static __cold void io_sqd_update_thread_idle(struct io_sq_data *sqd)
{
struct io_ring_ctx *ctx;
unsigned sq_thread_idle = 0;
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
sq_thread_idle = max(sq_thread_idle, ctx->sq_thread_idle);
sqd->sq_thread_idle = sq_thread_idle;
}
static bool io_sqd_handle_event(struct io_sq_data *sqd)
{
bool did_sig = false;
struct ksignal ksig;
if (test_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state) ||
signal_pending(current)) {
mutex_unlock(&sqd->lock);
if (signal_pending(current))
did_sig = get_signal(&ksig);
cond_resched();
mutex_lock(&sqd->lock);
}
return did_sig || test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);
}
static int io_sq_thread(void *data)
{
struct io_sq_data *sqd = data;
struct io_ring_ctx *ctx;
unsigned long timeout = 0;
char buf[TASK_COMM_LEN];
DEFINE_WAIT(wait);
snprintf(buf, sizeof(buf), "iou-sqp-%d", sqd->task_pid);
set_task_comm(current, buf);
if (sqd->sq_cpu != -1)
set_cpus_allowed_ptr(current, cpumask_of(sqd->sq_cpu));
else
set_cpus_allowed_ptr(current, cpu_online_mask);
current->flags |= PF_NO_SETAFFINITY;
audit_alloc_kernel(current);
mutex_lock(&sqd->lock);
while (1) {
bool cap_entries, sqt_spin = false;
if (io_sqd_events_pending(sqd) || signal_pending(current)) {
if (io_sqd_handle_event(sqd))
break;
timeout = jiffies + sqd->sq_thread_idle;
}
cap_entries = !list_is_singular(&sqd->ctx_list);
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
int ret = __io_sq_thread(ctx, cap_entries);
if (!sqt_spin && (ret > 0 || !wq_list_empty(&ctx->iopoll_list)))
sqt_spin = true;
}
if (io_run_task_work())
sqt_spin = true;
if (sqt_spin || !time_after(jiffies, timeout)) {
cond_resched();
if (sqt_spin)
timeout = jiffies + sqd->sq_thread_idle;
continue;
}
prepare_to_wait(&sqd->wait, &wait, TASK_INTERRUPTIBLE);
if (!io_sqd_events_pending(sqd) && !task_work_pending(current)) {
bool needs_sched = true;
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
atomic_or(IORING_SQ_NEED_WAKEUP,
&ctx->rings->sq_flags);
if ((ctx->flags & IORING_SETUP_IOPOLL) &&
!wq_list_empty(&ctx->iopoll_list)) {
needs_sched = false;
break;
}
/*
* Ensure the store of the wakeup flag is not
* reordered with the load of the SQ tail
*/
smp_mb__after_atomic();
if (io_sqring_entries(ctx)) {
needs_sched = false;
break;
}
}
if (needs_sched) {
mutex_unlock(&sqd->lock);
schedule();
mutex_lock(&sqd->lock);
}
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
atomic_andnot(IORING_SQ_NEED_WAKEUP,
&ctx->rings->sq_flags);
}
finish_wait(&sqd->wait, &wait);
timeout = jiffies + sqd->sq_thread_idle;
}
io_uring_cancel_generic(true, sqd);
sqd->thread = NULL;
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
atomic_or(IORING_SQ_NEED_WAKEUP, &ctx->rings->sq_flags);
io_run_task_work();
mutex_unlock(&sqd->lock);
audit_free(current);
complete(&sqd->exited);
do_exit(0);
}
struct io_wait_queue { struct io_wait_queue {
struct wait_queue_entry wq; struct wait_queue_entry wq;
struct io_ring_ctx *ctx; struct io_ring_ctx *ctx;
@ -5934,131 +5713,6 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
return ret; return ret;
} }
static void io_sq_thread_unpark(struct io_sq_data *sqd)
__releases(&sqd->lock)
{
WARN_ON_ONCE(sqd->thread == current);
/*
* Do the dance but not conditional clear_bit() because it'd race with
* other threads incrementing park_pending and setting the bit.
*/
clear_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
if (atomic_dec_return(&sqd->park_pending))
set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
mutex_unlock(&sqd->lock);
}
static void io_sq_thread_park(struct io_sq_data *sqd)
__acquires(&sqd->lock)
{
WARN_ON_ONCE(sqd->thread == current);
atomic_inc(&sqd->park_pending);
set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
mutex_lock(&sqd->lock);
if (sqd->thread)
wake_up_process(sqd->thread);
}
static void io_sq_thread_stop(struct io_sq_data *sqd)
{
WARN_ON_ONCE(sqd->thread == current);
WARN_ON_ONCE(test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state));
set_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);
mutex_lock(&sqd->lock);
if (sqd->thread)
wake_up_process(sqd->thread);
mutex_unlock(&sqd->lock);
wait_for_completion(&sqd->exited);
}
static void io_put_sq_data(struct io_sq_data *sqd)
{
if (refcount_dec_and_test(&sqd->refs)) {
WARN_ON_ONCE(atomic_read(&sqd->park_pending));
io_sq_thread_stop(sqd);
kfree(sqd);
}
}
static void io_sq_thread_finish(struct io_ring_ctx *ctx)
{
struct io_sq_data *sqd = ctx->sq_data;
if (sqd) {
io_sq_thread_park(sqd);
list_del_init(&ctx->sqd_list);
io_sqd_update_thread_idle(sqd);
io_sq_thread_unpark(sqd);
io_put_sq_data(sqd);
ctx->sq_data = NULL;
}
}
static struct io_sq_data *io_attach_sq_data(struct io_uring_params *p)
{
struct io_ring_ctx *ctx_attach;
struct io_sq_data *sqd;
struct fd f;
f = fdget(p->wq_fd);
if (!f.file)
return ERR_PTR(-ENXIO);
if (f.file->f_op != &io_uring_fops) {
fdput(f);
return ERR_PTR(-EINVAL);
}
ctx_attach = f.file->private_data;
sqd = ctx_attach->sq_data;
if (!sqd) {
fdput(f);
return ERR_PTR(-EINVAL);
}
if (sqd->task_tgid != current->tgid) {
fdput(f);
return ERR_PTR(-EPERM);
}
refcount_inc(&sqd->refs);
fdput(f);
return sqd;
}
static struct io_sq_data *io_get_sq_data(struct io_uring_params *p,
bool *attached)
{
struct io_sq_data *sqd;
*attached = false;
if (p->flags & IORING_SETUP_ATTACH_WQ) {
sqd = io_attach_sq_data(p);
if (!IS_ERR(sqd)) {
*attached = true;
return sqd;
}
/* fall through for EPERM case, setup new sqd/task */
if (PTR_ERR(sqd) != -EPERM)
return sqd;
}
sqd = kzalloc(sizeof(*sqd), GFP_KERNEL);
if (!sqd)
return ERR_PTR(-ENOMEM);
atomic_set(&sqd->park_pending, 0);
refcount_set(&sqd->refs, 1);
INIT_LIST_HEAD(&sqd->ctx_list);
mutex_init(&sqd->lock);
init_waitqueue_head(&sqd->wait);
init_completion(&sqd->exited);
return sqd;
}
/* /*
* Ensure the UNIX gc is aware of our file set, so we are certain that * Ensure the UNIX gc is aware of our file set, so we are certain that
* the io_uring can be safely unregistered on process exit, even if we have * the io_uring can be safely unregistered on process exit, even if we have
@ -6495,8 +6149,8 @@ static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx,
return io_wq_create(concurrency, &data); return io_wq_create(concurrency, &data);
} }
static __cold int io_uring_alloc_task_context(struct task_struct *task, __cold int io_uring_alloc_task_context(struct task_struct *task,
struct io_ring_ctx *ctx) struct io_ring_ctx *ctx)
{ {
struct io_uring_task *tctx; struct io_uring_task *tctx;
int ret; int ret;
@ -6554,96 +6208,6 @@ void __io_uring_free(struct task_struct *tsk)
tsk->io_uring = NULL; tsk->io_uring = NULL;
} }
static __cold int io_sq_offload_create(struct io_ring_ctx *ctx,
struct io_uring_params *p)
{
int ret;
/* Retain compatibility with failing for an invalid attach attempt */
if ((ctx->flags & (IORING_SETUP_ATTACH_WQ | IORING_SETUP_SQPOLL)) ==
IORING_SETUP_ATTACH_WQ) {
struct fd f;
f = fdget(p->wq_fd);
if (!f.file)
return -ENXIO;
if (f.file->f_op != &io_uring_fops) {
fdput(f);
return -EINVAL;
}
fdput(f);
}
if (ctx->flags & IORING_SETUP_SQPOLL) {
struct task_struct *tsk;
struct io_sq_data *sqd;
bool attached;
ret = security_uring_sqpoll();
if (ret)
return ret;
sqd = io_get_sq_data(p, &attached);
if (IS_ERR(sqd)) {
ret = PTR_ERR(sqd);
goto err;
}
ctx->sq_creds = get_current_cred();
ctx->sq_data = sqd;
ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
if (!ctx->sq_thread_idle)
ctx->sq_thread_idle = HZ;
io_sq_thread_park(sqd);
list_add(&ctx->sqd_list, &sqd->ctx_list);
io_sqd_update_thread_idle(sqd);
/* don't attach to a dying SQPOLL thread, would be racy */
ret = (attached && !sqd->thread) ? -ENXIO : 0;
io_sq_thread_unpark(sqd);
if (ret < 0)
goto err;
if (attached)
return 0;
if (p->flags & IORING_SETUP_SQ_AFF) {
int cpu = p->sq_thread_cpu;
ret = -EINVAL;
if (cpu >= nr_cpu_ids || !cpu_online(cpu))
goto err_sqpoll;
sqd->sq_cpu = cpu;
} else {
sqd->sq_cpu = -1;
}
sqd->task_pid = current->pid;
sqd->task_tgid = current->tgid;
tsk = create_io_thread(io_sq_thread, sqd, NUMA_NO_NODE);
if (IS_ERR(tsk)) {
ret = PTR_ERR(tsk);
goto err_sqpoll;
}
sqd->thread = tsk;
ret = io_uring_alloc_task_context(tsk, ctx);
wake_up_new_task(tsk);
if (ret)
goto err;
} else if (p->flags & IORING_SETUP_SQ_AFF) {
/* Can't have SQ_AFF without SQPOLL */
ret = -EINVAL;
goto err;
}
return 0;
err_sqpoll:
complete(&ctx->sq_data->exited);
err:
io_sq_thread_finish(ctx);
return ret;
}
static inline void __io_unaccount_mem(struct user_struct *user, static inline void __io_unaccount_mem(struct user_struct *user,
unsigned long nr_pages) unsigned long nr_pages)
{ {
@ -7755,8 +7319,7 @@ static s64 tctx_inflight(struct io_uring_task *tctx, bool tracked)
* Find any io_uring ctx that this task has registered or done IO on, and cancel * Find any io_uring ctx that this task has registered or done IO on, and cancel
* requests. @sqd should be not-null IFF it's an SQPOLL thread cancellation. * requests. @sqd should be not-null IFF it's an SQPOLL thread cancellation.
*/ */
static __cold void io_uring_cancel_generic(bool cancel_all, __cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
struct io_sq_data *sqd)
{ {
struct io_uring_task *tctx = current->io_uring; struct io_uring_task *tctx = current->io_uring;
struct io_ring_ctx *ctx; struct io_ring_ctx *ctx;
@ -8034,24 +7597,6 @@ static unsigned long io_uring_nommu_get_unmapped_area(struct file *file,
#endif /* !CONFIG_MMU */ #endif /* !CONFIG_MMU */
static int io_sqpoll_wait_sq(struct io_ring_ctx *ctx)
{
DEFINE_WAIT(wait);
do {
if (!io_sqring_full(ctx))
break;
prepare_to_wait(&ctx->sqo_sq_wait, &wait, TASK_INTERRUPTIBLE);
if (!io_sqring_full(ctx))
break;
schedule();
} while (!signal_pending(current));
finish_wait(&ctx->sqo_sq_wait, &wait);
return 0;
}
static int io_validate_ext_arg(unsigned flags, const void __user *argp, size_t argsz) static int io_validate_ext_arg(unsigned flags, const void __user *argp, size_t argsz)
{ {
if (flags & IORING_ENTER_EXT_ARG) { if (flags & IORING_ENTER_EXT_ARG) {

34
io_uring/io_uring.h
View File

@ -64,6 +64,34 @@ static inline void io_commit_cqring(struct io_ring_ctx *ctx)
smp_store_release(&ctx->rings->cq.tail, ctx->cached_cq_tail); smp_store_release(&ctx->rings->cq.tail, ctx->cached_cq_tail);
} }
static inline bool io_sqring_full(struct io_ring_ctx *ctx)
{
struct io_rings *r = ctx->rings;
return READ_ONCE(r->sq.tail) - ctx->cached_sq_head == ctx->sq_entries;
}
static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
{
struct io_rings *rings = ctx->rings;
/* make sure SQ entry isn't read before tail */
return smp_load_acquire(&rings->sq.tail) - ctx->cached_sq_head;
}
static inline bool io_run_task_work(void)
{
if (test_thread_flag(TIF_NOTIFY_SIGNAL) || task_work_pending(current)) {
__set_current_state(TASK_RUNNING);
clear_notify_signal();
if (task_work_pending(current))
task_work_run();
return true;
}
return false;
}
void __io_req_complete(struct io_kiocb *req, unsigned issue_flags); void __io_req_complete(struct io_kiocb *req, unsigned issue_flags);
void io_req_complete_post(struct io_kiocb *req); void io_req_complete_post(struct io_kiocb *req);
void __io_req_complete_post(struct io_kiocb *req); void __io_req_complete_post(struct io_kiocb *req);
@ -101,6 +129,12 @@ void io_req_tw_post_queue(struct io_kiocb *req, s32 res, u32 cflags);
void io_req_task_complete(struct io_kiocb *req, bool *locked); void io_req_task_complete(struct io_kiocb *req, bool *locked);
void io_req_task_queue_fail(struct io_kiocb *req, int ret); void io_req_task_queue_fail(struct io_kiocb *req, int ret);
int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd); int io_try_cancel(struct io_kiocb *req, struct io_cancel_data *cd);
__cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd);
int io_uring_alloc_task_context(struct task_struct *task,
struct io_ring_ctx *ctx);
int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr);
int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin);
void io_free_req(struct io_kiocb *req); void io_free_req(struct io_kiocb *req);
void io_queue_next(struct io_kiocb *req); void io_queue_next(struct io_kiocb *req);

426
io_uring/sqpoll.c Normal file
View File

@ -0,0 +1,426 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Contains the core associated with submission side polling of the SQ
* ring, offloading submissions from the application to a kernel thread.
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/audit.h>
#include <linux/security.h>
#include <linux/io_uring.h>
#include <uapi/linux/io_uring.h>
#include "io_uring_types.h"
#include "io_uring.h"
#include "sqpoll.h"
#define IORING_SQPOLL_CAP_ENTRIES_VALUE 8
enum {
IO_SQ_THREAD_SHOULD_STOP = 0,
IO_SQ_THREAD_SHOULD_PARK,
};
void io_sq_thread_unpark(struct io_sq_data *sqd)
__releases(&sqd->lock)
{
WARN_ON_ONCE(sqd->thread == current);
/*
* Do the dance but not conditional clear_bit() because it'd race with
* other threads incrementing park_pending and setting the bit.
*/
clear_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
if (atomic_dec_return(&sqd->park_pending))
set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
mutex_unlock(&sqd->lock);
}
void io_sq_thread_park(struct io_sq_data *sqd)
__acquires(&sqd->lock)
{
WARN_ON_ONCE(sqd->thread == current);
atomic_inc(&sqd->park_pending);
set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
mutex_lock(&sqd->lock);
if (sqd->thread)
wake_up_process(sqd->thread);
}
void io_sq_thread_stop(struct io_sq_data *sqd)
{
WARN_ON_ONCE(sqd->thread == current);
WARN_ON_ONCE(test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state));
set_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);
mutex_lock(&sqd->lock);
if (sqd->thread)
wake_up_process(sqd->thread);
mutex_unlock(&sqd->lock);
wait_for_completion(&sqd->exited);
}
void io_put_sq_data(struct io_sq_data *sqd)
{
if (refcount_dec_and_test(&sqd->refs)) {
WARN_ON_ONCE(atomic_read(&sqd->park_pending));
io_sq_thread_stop(sqd);
kfree(sqd);
}
}
static __cold void io_sqd_update_thread_idle(struct io_sq_data *sqd)
{
struct io_ring_ctx *ctx;
unsigned sq_thread_idle = 0;
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
sq_thread_idle = max(sq_thread_idle, ctx->sq_thread_idle);
sqd->sq_thread_idle = sq_thread_idle;
}
void io_sq_thread_finish(struct io_ring_ctx *ctx)
{
struct io_sq_data *sqd = ctx->sq_data;
if (sqd) {
io_sq_thread_park(sqd);
list_del_init(&ctx->sqd_list);
io_sqd_update_thread_idle(sqd);
io_sq_thread_unpark(sqd);
io_put_sq_data(sqd);
ctx->sq_data = NULL;
}
}
static struct io_sq_data *io_attach_sq_data(struct io_uring_params *p)
{
struct io_ring_ctx *ctx_attach;
struct io_sq_data *sqd;
struct fd f;
f = fdget(p->wq_fd);
if (!f.file)
return ERR_PTR(-ENXIO);
if (!io_is_uring_fops(f.file)) {
fdput(f);
return ERR_PTR(-EINVAL);
}
ctx_attach = f.file->private_data;
sqd = ctx_attach->sq_data;
if (!sqd) {
fdput(f);
return ERR_PTR(-EINVAL);
}
if (sqd->task_tgid != current->tgid) {
fdput(f);
return ERR_PTR(-EPERM);
}
refcount_inc(&sqd->refs);
fdput(f);
return sqd;
}
static struct io_sq_data *io_get_sq_data(struct io_uring_params *p,
bool *attached)
{
struct io_sq_data *sqd;
*attached = false;
if (p->flags & IORING_SETUP_ATTACH_WQ) {
sqd = io_attach_sq_data(p);
if (!IS_ERR(sqd)) {
*attached = true;
return sqd;
}
/* fall through for EPERM case, setup new sqd/task */
if (PTR_ERR(sqd) != -EPERM)
return sqd;
}
sqd = kzalloc(sizeof(*sqd), GFP_KERNEL);
if (!sqd)
return ERR_PTR(-ENOMEM);
atomic_set(&sqd->park_pending, 0);
refcount_set(&sqd->refs, 1);
INIT_LIST_HEAD(&sqd->ctx_list);
mutex_init(&sqd->lock);
init_waitqueue_head(&sqd->wait);
init_completion(&sqd->exited);
return sqd;
}
static inline bool io_sqd_events_pending(struct io_sq_data *sqd)
{
return READ_ONCE(sqd->state);
}
static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
{
unsigned int to_submit;
int ret = 0;
to_submit = io_sqring_entries(ctx);
/* if we're handling multiple rings, cap submit size for fairness */
if (cap_entries && to_submit > IORING_SQPOLL_CAP_ENTRIES_VALUE)
to_submit = IORING_SQPOLL_CAP_ENTRIES_VALUE;
if (!wq_list_empty(&ctx->iopoll_list) || to_submit) {
const struct cred *creds = NULL;
if (ctx->sq_creds != current_cred())
creds = override_creds(ctx->sq_creds);
mutex_lock(&ctx->uring_lock);
if (!wq_list_empty(&ctx->iopoll_list))
io_do_iopoll(ctx, true);
/*
* Don't submit if refs are dying, good for io_uring_register(),
* but also it is relied upon by io_ring_exit_work()
*/
if (to_submit && likely(!percpu_ref_is_dying(&ctx->refs)) &&
!(ctx->flags & IORING_SETUP_R_DISABLED))
ret = io_submit_sqes(ctx, to_submit);
mutex_unlock(&ctx->uring_lock);
if (to_submit && wq_has_sleeper(&ctx->sqo_sq_wait))
wake_up(&ctx->sqo_sq_wait);
if (creds)
revert_creds(creds);
}
return ret;
}
static bool io_sqd_handle_event(struct io_sq_data *sqd)
{
bool did_sig = false;
struct ksignal ksig;
if (test_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state) ||
signal_pending(current)) {
mutex_unlock(&sqd->lock);
if (signal_pending(current))
did_sig = get_signal(&ksig);
cond_resched();
mutex_lock(&sqd->lock);
}
return did_sig || test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);
}
static int io_sq_thread(void *data)
{
struct io_sq_data *sqd = data;
struct io_ring_ctx *ctx;
unsigned long timeout = 0;
char buf[TASK_COMM_LEN];
DEFINE_WAIT(wait);
snprintf(buf, sizeof(buf), "iou-sqp-%d", sqd->task_pid);
set_task_comm(current, buf);
if (sqd->sq_cpu != -1)
set_cpus_allowed_ptr(current, cpumask_of(sqd->sq_cpu));
else
set_cpus_allowed_ptr(current, cpu_online_mask);
current->flags |= PF_NO_SETAFFINITY;
audit_alloc_kernel(current);
mutex_lock(&sqd->lock);
while (1) {
bool cap_entries, sqt_spin = false;
if (io_sqd_events_pending(sqd) || signal_pending(current)) {
if (io_sqd_handle_event(sqd))
break;
timeout = jiffies + sqd->sq_thread_idle;
}
cap_entries = !list_is_singular(&sqd->ctx_list);
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
int ret = __io_sq_thread(ctx, cap_entries);
if (!sqt_spin && (ret > 0 || !wq_list_empty(&ctx->iopoll_list)))
sqt_spin = true;
}
if (io_run_task_work())
sqt_spin = true;
if (sqt_spin || !time_after(jiffies, timeout)) {
cond_resched();
if (sqt_spin)
timeout = jiffies + sqd->sq_thread_idle;
continue;
}
prepare_to_wait(&sqd->wait, &wait, TASK_INTERRUPTIBLE);
if (!io_sqd_events_pending(sqd) && !task_work_pending(current)) {
bool needs_sched = true;
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
atomic_or(IORING_SQ_NEED_WAKEUP,
&ctx->rings->sq_flags);
if ((ctx->flags & IORING_SETUP_IOPOLL) &&
!wq_list_empty(&ctx->iopoll_list)) {
needs_sched = false;
break;
}
/*
* Ensure the store of the wakeup flag is not
* reordered with the load of the SQ tail
*/
smp_mb__after_atomic();
if (io_sqring_entries(ctx)) {
needs_sched = false;
break;
}
}
if (needs_sched) {
mutex_unlock(&sqd->lock);
schedule();
mutex_lock(&sqd->lock);
}
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
atomic_andnot(IORING_SQ_NEED_WAKEUP,
&ctx->rings->sq_flags);
}
finish_wait(&sqd->wait, &wait);
timeout = jiffies + sqd->sq_thread_idle;
}
io_uring_cancel_generic(true, sqd);
sqd->thread = NULL;
list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
atomic_or(IORING_SQ_NEED_WAKEUP, &ctx->rings->sq_flags);
io_run_task_work();
mutex_unlock(&sqd->lock);
audit_free(current);
complete(&sqd->exited);
do_exit(0);
}
int io_sqpoll_wait_sq(struct io_ring_ctx *ctx)
{
DEFINE_WAIT(wait);
do {
if (!io_sqring_full(ctx))
break;
prepare_to_wait(&ctx->sqo_sq_wait, &wait, TASK_INTERRUPTIBLE);
if (!io_sqring_full(ctx))
break;
schedule();
} while (!signal_pending(current));
finish_wait(&ctx->sqo_sq_wait, &wait);
return 0;
}
__cold int io_sq_offload_create(struct io_ring_ctx *ctx,
struct io_uring_params *p)
{
int ret;
/* Retain compatibility with failing for an invalid attach attempt */
if ((ctx->flags & (IORING_SETUP_ATTACH_WQ | IORING_SETUP_SQPOLL)) ==
IORING_SETUP_ATTACH_WQ) {
struct fd f;
f = fdget(p->wq_fd);
if (!f.file)
return -ENXIO;
if (!io_is_uring_fops(f.file)) {
fdput(f);
return -EINVAL;
}
fdput(f);
}
if (ctx->flags & IORING_SETUP_SQPOLL) {
struct task_struct *tsk;
struct io_sq_data *sqd;
bool attached;
ret = security_uring_sqpoll();
if (ret)
return ret;
sqd = io_get_sq_data(p, &attached);
if (IS_ERR(sqd)) {
ret = PTR_ERR(sqd);
goto err;
}
ctx->sq_creds = get_current_cred();
ctx->sq_data = sqd;
ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
if (!ctx->sq_thread_idle)
ctx->sq_thread_idle = HZ;
io_sq_thread_park(sqd);
list_add(&ctx->sqd_list, &sqd->ctx_list);
io_sqd_update_thread_idle(sqd);
/* don't attach to a dying SQPOLL thread, would be racy */
ret = (attached && !sqd->thread) ? -ENXIO : 0;
io_sq_thread_unpark(sqd);
if (ret < 0)
goto err;
if (attached)
return 0;
if (p->flags & IORING_SETUP_SQ_AFF) {
int cpu = p->sq_thread_cpu;
ret = -EINVAL;
if (cpu >= nr_cpu_ids || !cpu_online(cpu))
goto err_sqpoll;
sqd->sq_cpu = cpu;
} else {
sqd->sq_cpu = -1;
}
sqd->task_pid = current->pid;
sqd->task_tgid = current->tgid;
tsk = create_io_thread(io_sq_thread, sqd, NUMA_NO_NODE);
if (IS_ERR(tsk)) {
ret = PTR_ERR(tsk);
goto err_sqpoll;
}
sqd->thread = tsk;
ret = io_uring_alloc_task_context(tsk, ctx);
wake_up_new_task(tsk);
if (ret)
goto err;
} else if (p->flags & IORING_SETUP_SQ_AFF) {
/* Can't have SQ_AFF without SQPOLL */
ret = -EINVAL;
goto err;
}
return 0;
err_sqpoll:
complete(&ctx->sq_data->exited);
err:
io_sq_thread_finish(ctx);
return ret;
}

29
io_uring/sqpoll.h Normal file
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@ -0,0 +1,29 @@
// SPDX-License-Identifier: GPL-2.0
struct io_sq_data {
refcount_t refs;
atomic_t park_pending;
struct mutex lock;
/* ctx's that are using this sqd */
struct list_head ctx_list;
struct task_struct *thread;
struct wait_queue_head wait;
unsigned sq_thread_idle;
int sq_cpu;
pid_t task_pid;
pid_t task_tgid;
unsigned long state;
struct completion exited;
};
int io_sq_offload_create(struct io_ring_ctx *ctx, struct io_uring_params *p);
void io_sq_thread_finish(struct io_ring_ctx *ctx);
void io_sq_thread_stop(struct io_sq_data *sqd);
void io_sq_thread_park(struct io_sq_data *sqd);
void io_sq_thread_unpark(struct io_sq_data *sqd);
void io_put_sq_data(struct io_sq_data *sqd);
int io_sqpoll_wait_sq(struct io_ring_ctx *ctx);