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io.cfa @ 44e37ef

ADTarm-ehast-experimentalenumforall-pointer-decayjacob/cs343-translationnew-ast-unique-exprpthread-emulationqualifiedEnum

Last change on this file since 44e37ef was fe9468e2, checked in by Thierry Delisle <tdelisle@…>, 4 years ago
Added function thread_rand as a tls-safe version of tls_rand()
Property mode set to `100644`
File size: 16.2 KB

Rev	Line
[ecf6b46]	1	//
	2	// Cforall Version 1.0.0 Copyright (C) 2020 University of Waterloo
	3	//
	4	// The contents of this file are covered under the licence agreement in the
	5	// file "LICENCE" distributed with Cforall.
	6	//
	7	// io.cfa --
	8	//
	9	// Author : Thierry Delisle
	10	// Created On : Thu Apr 23 17:31:00 2020
	11	// Last Modified By :
	12	// Last Modified On :
	13	// Update Count :
	14	//
	15
[3e2b9c9]	16	#define __cforall_thread__
	17
[20ab637]	18	#if defined(__CFA_DEBUG__)
	19	// #define __CFA_DEBUG_PRINT_IO__
[e660761]	20	// #define __CFA_DEBUG_PRINT_IO_CORE__
[20ab637]	21	#endif
[4069faad]	22
[f6660520]	23
[3e2b9c9]	24	#if defined(CFA_HAVE_LINUX_IO_URING_H)
[31bb2e1]	25	#define _GNU_SOURCE /* See feature_test_macros(7) */
	26	#include <errno.h>
[3e2b9c9]	27	#include <signal.h>
[31bb2e1]	28	#include <stdint.h>
	29	#include <string.h>
	30	#include <unistd.h>
	31
[92976d9]	32	extern "C" {
[f00b26d4]	33	#include <sys/epoll.h>
[92976d9]	34	#include <sys/syscall.h>
	35
	36	#include <linux/io_uring.h>
	37	}
	38
[3e2b9c9]	39	#include "stats.hfa"
	40	#include "kernel.hfa"
	41	#include "kernel/fwd.hfa"
	42	#include "io/types.hfa"
[185efe6]	43
[2fafe7e]	44	// returns true of acquired as leader or second leader
	45	static inline bool try_lock( __leaderlock_t & this ) {
	46	const uintptr_t thrd = 1z \| (uintptr_t)active_thread();
	47	bool block;
	48	disable_interrupts();
	49	for() {
	50	struct $thread * expected = this.value;
	51	if( 1p != expected && 0p != expected ) {
	52	/* paranoid */ verify( thrd != (uintptr_t)expected ); // We better not already be the next leader
	53	enable_interrupts( __cfaabi_dbg_ctx );
	54	return false;
	55	}
	56	struct $thread * desired;
	57	if( 0p == expected ) {
	58	// If the lock isn't locked acquire it, no need to block
	59	desired = 1p;
	60	block = false;
	61	}
	62	else {
	63	// If the lock is already locked try becomming the next leader
	64	desired = (struct $thread *)thrd;
	65	block = true;
	66	}
	67	if( __atomic_compare_exchange_n(&this.value, &expected, desired, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) break;
	68	}
	69	if( block ) {
	70	enable_interrupts( __cfaabi_dbg_ctx );
[e235429]	71	park();
[2fafe7e]	72	disable_interrupts();
	73	}
	74	return true;
	75	}
	76
	77	static inline bool next( __leaderlock_t & this ) {
[8fc652e0]	78	/* paranoid */ verify( ! __preemption_enabled() );
[2fafe7e]	79	struct $thread * nextt;
	80	for() {
	81	struct $thread * expected = this.value;
	82	/* paranoid */ verify( (1 & (uintptr_t)expected) == 1 ); // The lock better be locked
	83
	84	struct $thread * desired;
	85	if( 1p == expected ) {
	86	// No next leader, just unlock
	87	desired = 0p;
	88	nextt = 0p;
	89	}
	90	else {
	91	// There is a next leader, remove but keep locked
	92	desired = 1p;
	93	nextt = (struct $thread *)(~1z & (uintptr_t)expected);
	94	}
	95	if( __atomic_compare_exchange_n(&this.value, &expected, desired, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) break;
	96	}
	97
	98	if(nextt) {
[b4b63e8]	99	unpark( nextt );
[2fafe7e]	100	enable_interrupts( __cfaabi_dbg_ctx );
	101	return true;
	102	}
	103	enable_interrupts( __cfaabi_dbg_ctx );
	104	return false;
	105	}
	106
[92976d9]	107	//=============================================================================================
[3e2b9c9]	108	// I/O Syscall
[92976d9]	109	//=============================================================================================
[3e2b9c9]	110	static int __io_uring_enter( struct __io_data & ring, unsigned to_submit, bool get ) {
[20ab637]	111	bool need_sys_to_submit = false;
	112	bool need_sys_to_complete = false;
	113	unsigned flags = 0;
	114
	115	TO_SUBMIT:
	116	if( to_submit > 0 ) {
	117	if( !(ring.ring_flags & IORING_SETUP_SQPOLL) ) {
	118	need_sys_to_submit = true;
	119	break TO_SUBMIT;
	120	}
	121	if( (*ring.submit_q.flags) & IORING_SQ_NEED_WAKEUP ) {
	122	need_sys_to_submit = true;
	123	flags \|= IORING_ENTER_SQ_WAKEUP;
	124	}
	125	}
	126
	127	if( get && !(ring.ring_flags & IORING_SETUP_SQPOLL) ) {
	128	flags \|= IORING_ENTER_GETEVENTS;
	129	if( (ring.ring_flags & IORING_SETUP_IOPOLL) ) {
	130	need_sys_to_complete = true;
	131	}
	132	}
	133
	134	int ret = 0;
	135	if( need_sys_to_submit \|\| need_sys_to_complete ) {
[b982fb2]	136	ret = syscall( __NR_io_uring_enter, ring.fd, to_submit, 0, flags, (sigset_t *)0p, _NSIG / 8);
[20ab637]	137	if( ret < 0 ) {
	138	switch((int)errno) {
	139	case EAGAIN:
	140	case EINTR:
	141	ret = -1;
	142	break;
	143	default:
	144	abort( "KERNEL ERROR: IO_URING SYSCALL - (%d) %s\n", (int)errno, strerror(errno) );
	145	}
	146	}
	147	}
	148
	149	// Memory barrier
	150	__atomic_thread_fence( __ATOMIC_SEQ_CST );
	151	return ret;
	152	}
	153
[92976d9]	154	//=============================================================================================
	155	// I/O Polling
	156	//=============================================================================================
[1d5e4711]	157	static unsigned __collect_submitions( struct __io_data & ring );
[4998155]	158	static __u32 __release_consumed_submission( struct __io_data & ring );
[1d5e4711]	159
[f00b26d4]	160	static inline void process(struct io_uring_cqe & cqe ) {
[c402739f]	161	struct io_future_t * future = (struct io_future_t *)(uintptr_t)cqe.user_data;
[fe9468e2]	162	__cfadbg_print_safe( io, "Kernel I/O : Syscall completed : cqe %p, result %d for %p\n", &cqe, cqe.res, future );
[5751a56]	163
[c402739f]	164	fulfil( *future, cqe.res );
[5751a56]	165	}
	166
[92976d9]	167	// Process a single completion message from the io_uring
	168	// This is NOT thread-safe
[f00b26d4]	169	static [int, bool] __drain_io( & struct __io_data ring ) {
[8fc652e0]	170	/* paranoid */ verify( ! __preemption_enabled() );
[e46c753]	171
[5dadc9b]	172	unsigned to_submit = 0;
[f00b26d4]	173	if( ring.poller_submits ) {
[5dadc9b]	174	// If the poller thread also submits, then we need to aggregate the submissions which are ready
[e46c753]	175	to_submit = __collect_submitions( ring );
[5dadc9b]	176	}
	177
[f00b26d4]	178	int ret = __io_uring_enter(ring, to_submit, true);
[20ab637]	179	if( ret < 0 ) {
	180	return [0, true];
	181	}
[1d5e4711]	182
[20ab637]	183	// update statistics
	184	if (to_submit > 0) {
[1d5e4711]	185	__STATS__( true,
	186	if( to_submit > 0 ) {
	187	io.submit_q.submit_avg.rdy += to_submit;
	188	io.submit_q.submit_avg.csm += ret;
	189	io.submit_q.submit_avg.cnt += 1;
	190	}
	191	)
[6f121b8]	192	}
	193
[20ab637]	194	// Release the consumed SQEs
	195	__release_consumed_submission( ring );
[6f121b8]	196
[d384787]	197	// Drain the queue
[92976d9]	198	unsigned head = *ring.completion_q.head;
[6f121b8]	199	unsigned tail = *ring.completion_q.tail;
[4998155]	200	const __u32 mask = *ring.completion_q.mask;
[6f121b8]	201
[d384787]	202	// Nothing was new return 0
	203	if (head == tail) {
[e46c753]	204	return [0, to_submit > 0];
[d384787]	205	}
[92976d9]	206
[4998155]	207	__u32 count = tail - head;
[1d5e4711]	208	/* paranoid */ verify( count != 0 );
[d384787]	209	for(i; count) {
[6f121b8]	210	unsigned idx = (head + i) & mask;
[d384787]	211	struct io_uring_cqe & cqe = ring.completion_q.cqes[idx];
[92976d9]	212
[d384787]	213	/* paranoid */ verify(&cqe);
[92976d9]	214
[f00b26d4]	215	process( cqe );
[d384787]	216	}
[2d8f7b0]	217
[92976d9]	218	// Mark to the kernel that the cqe has been seen
	219	// Ensure that the kernel only sees the new value of the head index after the CQEs have been read.
[6f121b8]	220	__atomic_thread_fence( __ATOMIC_SEQ_CST );
[d384787]	221	__atomic_fetch_add( ring.completion_q.head, count, __ATOMIC_RELAXED );
[92976d9]	222
[5dadc9b]	223	return [count, count > 0 \|\| to_submit > 0];
[92976d9]	224	}
	225
[f00b26d4]	226	void main( $io_ctx_thread & this ) {
	227	epoll_event ev;
[3e2b9c9]	228	__ioctx_register( this, ev );
[1539bbd]	229
[f00b26d4]	230	__cfadbg_print_safe(io_core, "Kernel I/O : IO poller %p for ring %p ready\n", &this, &this.ring);
[1539bbd]	231
[4e74466]	232	int reset = 0;
[61dd73d]	233	// Then loop until we need to start
[f00b26d4]	234	while(!__atomic_load_n(&this.done, __ATOMIC_SEQ_CST)) {
[61dd73d]	235	// Drain the io
[5dadc9b]	236	int count;
	237	bool again;
[13c5e19]	238	disable_interrupts();
[f00b26d4]	239	[count, again] = __drain_io( *this.ring );
[5dadc9b]	240
[13c5e19]	241	if(!again) reset++;
[3c039b0]	242
[13c5e19]	243	// Update statistics
[47746a2]	244	__STATS__( true,
	245	io.complete_q.completed_avg.val += count;
[dcb5f8d]	246	io.complete_q.completed_avg.cnt += 1;
[47746a2]	247	)
[13c5e19]	248	enable_interrupts( __cfaabi_dbg_ctx );
[3c039b0]	249
[5dadc9b]	250	// If we got something, just yield and check again
[4e74466]	251	if(reset < 5) {
[61dd73d]	252	yield();
	253	}
[5dadc9b]	254	// We didn't get anything baton pass to the slow poller
[61dd73d]	255	else {
[93526ef]	256	__STATS__( false,
[dcb5f8d]	257	io.complete_q.blocks += 1;
	258	)
[f00b26d4]	259	__cfadbg_print_safe(io_core, "Kernel I/O : Parking io poller %p\n", &this.self);
[5dadc9b]	260	reset = 0;
	261
[3e2b9c9]	262	// block this thread
	263	__ioctx_prepare_block( this, ev );
[f00b26d4]	264	wait( this.sem );
[f6660520]	265	}
	266	}
[61dd73d]	267
	268	__cfadbg_print_safe(io_core, "Kernel I/O : Fast poller for ring %p stopping\n", &this.ring);
	269	}
[f6660520]	270
[92976d9]	271	//=============================================================================================
	272	// I/O Submissions
	273	//=============================================================================================
	274
[2d8f7b0]	275	// Submition steps :
[e46c753]	276	// 1 - Allocate a queue entry. The ring already has memory for all entries but only the ones
[2d8f7b0]	277	// listed in sq.array are visible by the kernel. For those not listed, the kernel does not
	278	// offer any assurance that an entry is not being filled by multiple flags. Therefore, we
	279	// need to write an allocator that allows allocating concurrently.
	280	//
[e46c753]	281	// 2 - Actually fill the submit entry, this is the only simple and straightforward step.
[2d8f7b0]	282	//
[e46c753]	283	// 3 - Append the entry index to the array and adjust the tail accordingly. This operation
[2d8f7b0]	284	// needs to arrive to two concensus at the same time:
	285	// A - The order in which entries are listed in the array: no two threads must pick the
	286	// same index for their entries
	287	// B - When can the tail be update for the kernel. EVERY entries in the array between
	288	// head and tail must be fully filled and shouldn't ever be touched again.
	289	//
	290
[4998155]	291	[* struct io_uring_sqe, __u32] __submit_alloc( struct __io_data & ring, __u64 data ) {
[e46c753]	292	/* paranoid */ verify( data != 0 );
[13c5e19]	293
[6f121b8]	294	// Prepare the data we need
	295	__attribute((unused)) int len = 0;
	296	__attribute((unused)) int block = 0;
[4998155]	297	__u32 cnt = *ring.submit_q.num;
	298	__u32 mask = *ring.submit_q.mask;
[8ae4165]	299
[fe9468e2]	300	__u32 off = thread_rand();
[6f121b8]	301
	302	// Loop around looking for an available spot
[13c5e19]	303	for() {
[6f121b8]	304	// Look through the list starting at some offset
	305	for(i; cnt) {
[4998155]	306	__u64 expected = 0;
	307	__u32 idx = (i + off) & mask;
[6f121b8]	308	struct io_uring_sqe * sqe = &ring.submit_q.sqes[idx];
[4998155]	309	volatile __u64 * udata = &sqe->user_data;
[6f121b8]	310
	311	if( *udata == expected &&
	312	__atomic_compare_exchange_n( udata, &expected, data, true, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED ) )
	313	{
	314	// update statistics
[47746a2]	315	__STATS__( false,
	316	io.submit_q.alloc_avg.val += len;
	317	io.submit_q.alloc_avg.block += block;
	318	io.submit_q.alloc_avg.cnt += 1;
	319	)
[6f121b8]	320
[13c5e19]	321
[6f121b8]	322	// Success return the data
	323	return [sqe, idx];
	324	}
	325	verify(expected != data);
[2489d31]	326
[6f121b8]	327	len ++;
	328	}
[2489d31]	329
[6f121b8]	330	block++;
	331	yield();
	332	}
[2489d31]	333	}
	334
[4998155]	335	static inline __u32 __submit_to_ready_array( struct __io_data & ring, __u32 idx, const __u32 mask ) {
[df40a56]	336	/* paranoid */ verify( idx <= mask );
	337	/* paranoid */ verify( idx != -1ul32 );
	338
	339	// We need to find a spot in the ready array
	340	__attribute((unused)) int len = 0;
	341	__attribute((unused)) int block = 0;
[4998155]	342	__u32 ready_mask = ring.submit_q.ready_cnt - 1;
[df40a56]	343
[fe9468e2]	344	__u32 off = thread_rand();
[df40a56]	345
[4998155]	346	__u32 picked;
[df40a56]	347	LOOKING: for() {
	348	for(i; ring.submit_q.ready_cnt) {
	349	picked = (i + off) & ready_mask;
[4998155]	350	__u32 expected = -1ul32;
[df40a56]	351	if( __atomic_compare_exchange_n( &ring.submit_q.ready[picked], &expected, idx, true, __ATOMIC_SEQ_CST, __ATOMIC_RELAXED ) ) {
	352	break LOOKING;
	353	}
	354	verify(expected != idx);
	355
	356	len ++;
	357	}
	358
	359	block++;
[2fafe7e]	360
	361	__u32 released = __release_consumed_submission( ring );
	362	if( released == 0 ) {
[34b61882]	363	yield();
	364	}
[df40a56]	365	}
	366
	367	// update statistics
[47746a2]	368	__STATS__( false,
	369	io.submit_q.look_avg.val += len;
	370	io.submit_q.look_avg.block += block;
	371	io.submit_q.look_avg.cnt += 1;
	372	)
[df40a56]	373
	374	return picked;
	375	}
	376
[4998155]	377	void __submit( struct io_context * ctx, __u32 idx ) __attribute__((nonnull (1))) {
[f00b26d4]	378	__io_data & ring = *ctx->thrd.ring;
[5dadc9b]	379	// Get now the data we definetely need
[4998155]	380	volatile __u32 * const tail = ring.submit_q.tail;
	381	const __u32 mask = *ring.submit_q.mask;
[2489d31]	382
[5dadc9b]	383	// There are 2 submission schemes, check which one we are using
[f00b26d4]	384	if( ring.poller_submits ) {
[5dadc9b]	385	// If the poller thread submits, then we just need to add this to the ready array
[df40a56]	386	__submit_to_ready_array( ring, idx, mask );
[5dadc9b]	387
[f00b26d4]	388	post( ctx->thrd.sem );
[5dadc9b]	389
[dd4e2d7]	390	__cfadbg_print_safe( io, "Kernel I/O : Added %u to ready for %p\n", idx, active_thread() );
[2d8f7b0]	391	}
[f00b26d4]	392	else if( ring.eager_submits ) {
[4998155]	393	__u32 picked = __submit_to_ready_array( ring, idx, mask );
[e46c753]	394
[2fafe7e]	395	#if defined(LEADER_LOCK)
	396	if( !try_lock(ring.submit_q.submit_lock) ) {
[47746a2]	397	__STATS__( false,
	398	io.submit_q.helped += 1;
	399	)
[e46c753]	400	return;
	401	}
[8fc652e0]	402	/* paranoid */ verify( ! __preemption_enabled() );
[2fafe7e]	403	__STATS__( true,
	404	io.submit_q.leader += 1;
	405	)
	406	#else
	407	for() {
	408	yield();
	409
	410	if( try_lock(ring.submit_q.submit_lock __cfaabi_dbg_ctx2) ) {
	411	__STATS__( false,
	412	io.submit_q.leader += 1;
	413	)
	414	break;
	415	}
	416
	417	// If some one else collected our index, we are done
	418	#warning ABA problem
	419	if( ring.submit_q.ready[picked] != idx ) {
	420	__STATS__( false,
	421	io.submit_q.helped += 1;
	422	)
	423	return;
	424	}
[e46c753]	425
[47746a2]	426	__STATS__( false,
[2fafe7e]	427	io.submit_q.busy += 1;
[47746a2]	428	)
[e46c753]	429	}
[2fafe7e]	430	#endif
[e46c753]	431
	432	// We got the lock
[be36ec3]	433	// Collect the submissions
[e46c753]	434	unsigned to_submit = __collect_submitions( ring );
	435
[be36ec3]	436	// Actually submit
	437	int ret = __io_uring_enter( ring, to_submit, false );
[309d814]	438
[2fafe7e]	439	#if defined(LEADER_LOCK)
[8fc652e0]	440	/* paranoid */ verify( ! __preemption_enabled() );
[2fafe7e]	441	next(ring.submit_q.submit_lock);
	442	#else
	443	unlock(ring.submit_q.submit_lock);
	444	#endif
[be36ec3]	445	if( ret < 0 ) return;
[e46c753]	446
	447	// Release the consumed SQEs
[34b61882]	448	__release_consumed_submission( ring );
[e46c753]	449
	450	// update statistics
[be36ec3]	451	__STATS__( false,
[47746a2]	452	io.submit_q.submit_avg.rdy += to_submit;
	453	io.submit_q.submit_avg.csm += ret;
	454	io.submit_q.submit_avg.cnt += 1;
	455	)
[e46c753]	456	}
[5dadc9b]	457	else {
	458	// get mutual exclusion
[2fafe7e]	459	#if defined(LEADER_LOCK)
	460	while(!try_lock(ring.submit_q.submit_lock));
	461	#else
	462	lock(ring.submit_q.submit_lock __cfaabi_dbg_ctx2);
	463	#endif
[2489d31]	464
[20ab637]	465	/* paranoid */ verifyf( ring.submit_q.sqes[ idx ].user_data != 0,
	466	/* paranoid */ "index %u already reclaimed\n"
	467	/* paranoid */ "head %u, prev %u, tail %u\n"
	468	/* paranoid */ "[-0: %u,-1: %u,-2: %u,-3: %u]\n",
	469	/* paranoid */ idx,
	470	/* paranoid / ring.submit_q.head, ring.submit_q.prev_head, *tail
	471	/* paranoid / ,ring.submit_q.array[ ((ring.submit_q.head) - 0) & (*ring.submit_q.mask) ]
	472	/* paranoid / ,ring.submit_q.array[ ((ring.submit_q.head) - 1) & (*ring.submit_q.mask) ]
	473	/* paranoid / ,ring.submit_q.array[ ((ring.submit_q.head) - 2) & (*ring.submit_q.mask) ]
	474	/* paranoid / ,ring.submit_q.array[ ((ring.submit_q.head) - 3) & (*ring.submit_q.mask) ]
	475	/* paranoid */ );
	476
[5dadc9b]	477	// Append to the list of ready entries
	478
	479	/* paranoid */ verify( idx <= mask );
[20ab637]	480	ring.submit_q.array[ (*tail) & mask ] = idx;
[5dadc9b]	481	__atomic_fetch_add(tail, 1ul32, __ATOMIC_SEQ_CST);
[d384787]	482
[5dadc9b]	483	// Submit however, many entries need to be submitted
[f00b26d4]	484	int ret = __io_uring_enter( ring, 1, false );
[5dadc9b]	485	if( ret < 0 ) {
	486	switch((int)errno) {
	487	default:
	488	abort( "KERNEL ERROR: IO_URING SUBMIT - %s\n", strerror(errno) );
	489	}
	490	}
[d384787]	491
[5dadc9b]	492	// update statistics
[47746a2]	493	__STATS__( false,
	494	io.submit_q.submit_avg.csm += 1;
	495	io.submit_q.submit_avg.cnt += 1;
	496	)
[5dadc9b]	497
[34b61882]	498	// Release the consumed SQEs
	499	__release_consumed_submission( ring );
[7bfc849]	500
[2fafe7e]	501	#if defined(LEADER_LOCK)
	502	next(ring.submit_q.submit_lock);
	503	#else
	504	unlock(ring.submit_q.submit_lock);
	505	#endif
[dd4e2d7]	506
	507	__cfadbg_print_safe( io, "Kernel I/O : Performed io_submit for %p, returned %d\n", active_thread(), ret );
[5dadc9b]	508	}
[2489d31]	509	}
[e46c753]	510
[d2b5d2d]	511	// #define PARTIAL_SUBMIT 32
[e46c753]	512	static unsigned __collect_submitions( struct __io_data & ring ) {
	513	/* paranoid */ verify( ring.submit_q.ready != 0p );
	514	/* paranoid */ verify( ring.submit_q.ready_cnt > 0 );
	515
	516	unsigned to_submit = 0;
[4998155]	517	__u32 tail = *ring.submit_q.tail;
	518	const __u32 mask = *ring.submit_q.mask;
[1095ccd]	519	#if defined(PARTIAL_SUBMIT)
	520	#if defined(LEADER_LOCK)
	521	#error PARTIAL_SUBMIT and LEADER_LOCK cannot co-exist
	522	#endif
	523	const __u32 cnt = ring.submit_q.ready_cnt > PARTIAL_SUBMIT ? PARTIAL_SUBMIT : ring.submit_q.ready_cnt;
	524	const __u32 offset = ring.submit_q.prev_ready;
	525	ring.submit_q.prev_ready += cnt;
	526	#else
	527	const __u32 cnt = ring.submit_q.ready_cnt;
	528	const __u32 offset = 0;
	529	#endif
[e46c753]	530
	531	// Go through the list of ready submissions
[1095ccd]	532	for( c; cnt ) {
	533	__u32 i = (offset + c) % ring.submit_q.ready_cnt;
	534
[e46c753]	535	// replace any submission with the sentinel, to consume it.
[4998155]	536	__u32 idx = __atomic_exchange_n( &ring.submit_q.ready[i], -1ul32, __ATOMIC_RELAXED);
[e46c753]	537
	538	// If it was already the sentinel, then we are done
	539	if( idx == -1ul32 ) continue;
	540
	541	// If we got a real submission, append it to the list
	542	ring.submit_q.array[ (tail + to_submit) & mask ] = idx & mask;
	543	to_submit++;
	544	}
	545
	546	// Increment the tail based on how many we are ready to submit
	547	__atomic_fetch_add(ring.submit_q.tail, to_submit, __ATOMIC_SEQ_CST);
	548
	549	return to_submit;
	550	}
[34b61882]	551
[4998155]	552	static __u32 __release_consumed_submission( struct __io_data & ring ) {
	553	const __u32 smask = *ring.submit_q.mask;
[732b406]	554
	555	if( !try_lock(ring.submit_q.release_lock __cfaabi_dbg_ctx2) ) return 0;
[4998155]	556	__u32 chead = *ring.submit_q.head;
	557	__u32 phead = ring.submit_q.prev_head;
[34b61882]	558	ring.submit_q.prev_head = chead;
[732b406]	559	unlock(ring.submit_q.release_lock);
	560
[4998155]	561	__u32 count = chead - phead;
[34b61882]	562	for( i; count ) {
[4998155]	563	__u32 idx = ring.submit_q.array[ (phead + i) & smask ];
[34b61882]	564	ring.submit_q.sqes[ idx ].user_data = 0;
	565	}
	566	return count;
	567	}
[47746a2]	568	#endif

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