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io.cfa@ 919a6b2

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ADT ast-experimental enum forall-pointer-decay pthread-emulation qualifiedEnum

Last change on this file since 919a6b2 was 078fb05, checked in by Thierry Delisle <tdelisle@…>, 4 years ago
Fixed a few warnings
Property mode set to `100644`
File size: 16.7 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__
[43784ac]	17	#define _GNU_SOURCE
[3e2b9c9]	18
[20ab637]	19	#if defined(__CFA_DEBUG__)
[d60d30e]	20	// #define __CFA_DEBUG_PRINT_IO__
	21	// #define __CFA_DEBUG_PRINT_IO_CORE__
[20ab637]	22	#endif
[4069faad]	23
[f6660520]	24
[3e2b9c9]	25	#if defined(CFA_HAVE_LINUX_IO_URING_H)
[31bb2e1]	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" {
	33	#include <sys/syscall.h>
[dddb3dd0]	34	#include <sys/eventfd.h>
[d3605f8]	35	#include <sys/uio.h>
[92976d9]	36
	37	#include <linux/io_uring.h>
	38	}
	39
[3e2b9c9]	40	#include "stats.hfa"
	41	#include "kernel.hfa"
	42	#include "kernel/fwd.hfa"
[e9c0b4c]	43	#include "kernel_private.hfa"
[3e2b9c9]	44	#include "io/types.hfa"
[185efe6]	45
[2fab24e3]	46	__attribute__((unused)) static const char * opcodes[] = {
[426f60c]	47	"OP_NOP",
	48	"OP_READV",
	49	"OP_WRITEV",
	50	"OP_FSYNC",
	51	"OP_READ_FIXED",
	52	"OP_WRITE_FIXED",
	53	"OP_POLL_ADD",
	54	"OP_POLL_REMOVE",
	55	"OP_SYNC_FILE_RANGE",
	56	"OP_SENDMSG",
	57	"OP_RECVMSG",
	58	"OP_TIMEOUT",
	59	"OP_TIMEOUT_REMOVE",
	60	"OP_ACCEPT",
	61	"OP_ASYNC_CANCEL",
	62	"OP_LINK_TIMEOUT",
	63	"OP_CONNECT",
	64	"OP_FALLOCATE",
	65	"OP_OPENAT",
	66	"OP_CLOSE",
	67	"OP_FILES_UPDATE",
	68	"OP_STATX",
	69	"OP_READ",
	70	"OP_WRITE",
	71	"OP_FADVISE",
	72	"OP_MADVISE",
	73	"OP_SEND",
	74	"OP_RECV",
	75	"OP_OPENAT2",
	76	"OP_EPOLL_CTL",
	77	"OP_SPLICE",
	78	"OP_PROVIDE_BUFFERS",
	79	"OP_REMOVE_BUFFERS",
	80	"OP_TEE",
	81	"INVALID_OP"
	82	};
	83
[11054eb]	84	static $io_context * __ioarbiter_allocate( $io_arbiter & this, __u32 idxs[], __u32 want );
	85	static void __ioarbiter_submit( $io_context * , __u32 idxs[], __u32 have, bool lazy );
	86	static void __ioarbiter_flush ( $io_context & );
[dddb3dd0]	87	static inline void __ioarbiter_notify( $io_context & ctx );
[92976d9]	88	//=============================================================================================
	89	// I/O Polling
	90	//=============================================================================================
[78da4ab]	91	static inline unsigned __flush( struct $io_context & );
	92	static inline __u32 __release_sqes( struct $io_context & );
[24e321c]	93	extern void __kernel_unpark( thread$ * thrd, unpark_hint );
[1d5e4711]	94
[c1c95b1]	95	bool __cfa_io_drain( processor * proc ) {
[dddb3dd0]	96	/* paranoid */ verify( ! __preemption_enabled() );
[e9c0b4c]	97	/* paranoid */ verify( ready_schedule_islocked() );
[dddb3dd0]	98	/* paranoid */ verify( proc );
	99	/* paranoid */ verify( proc->io.ctx );
[6f121b8]	100
[d384787]	101	// Drain the queue
[dddb3dd0]	102	$io_context * ctx = proc->io.ctx;
	103	unsigned head = *ctx->cq.head;
	104	unsigned tail = *ctx->cq.tail;
	105	const __u32 mask = *ctx->cq.mask;
[92976d9]	106
[4998155]	107	__u32 count = tail - head;
[dddb3dd0]	108	__STATS__( false, io.calls.drain++; io.calls.completed += count; )
[d60d30e]	109
[c1c95b1]	110	if(count == 0) return false;
	111
[d384787]	112	for(i; count) {
[6f121b8]	113	unsigned idx = (head + i) & mask;
[dddb3dd0]	114	volatile struct io_uring_cqe & cqe = ctx->cq.cqes[idx];
[92976d9]	115
[d384787]	116	/* paranoid */ verify(&cqe);
[92976d9]	117
[78da4ab]	118	struct io_future_t * future = (struct io_future_t *)(uintptr_t)cqe.user_data;
	119	__cfadbg_print_safe( io, "Kernel I/O : Syscall completed : cqe %p, result %d for %p\n", &cqe, cqe.res, future );
	120
[24e321c]	121	__kernel_unpark( fulfil( *future, cqe.res, false ), UNPARK_LOCAL );
[78da4ab]	122	}
	123
[dddb3dd0]	124	__cfadbg_print_safe(io, "Kernel I/O : %u completed\n", count);
[2d8f7b0]	125
[92976d9]	126	// Mark to the kernel that the cqe has been seen
	127	// Ensure that the kernel only sees the new value of the head index after the CQEs have been read.
[dddb3dd0]	128	__atomic_store_n( ctx->cq.head, head + count, __ATOMIC_SEQ_CST );
[92976d9]	129
[e9c0b4c]	130	/* paranoid */ verify( ready_schedule_islocked() );
[dddb3dd0]	131	/* paranoid */ verify( ! __preemption_enabled() );
	132
[c1c95b1]	133	return true;
[92976d9]	134	}
	135
[c7b2215]	136	bool __cfa_io_flush( processor * proc, int min_comp ) {
[dddb3dd0]	137	/* paranoid */ verify( ! __preemption_enabled() );
	138	/* paranoid */ verify( proc );
	139	/* paranoid */ verify( proc->io.ctx );
[1539bbd]	140
[d36bac7]	141	__attribute__((unused)) cluster * cltr = proc->cltr;
[dddb3dd0]	142	$io_context & ctx = *proc->io.ctx;
[78da4ab]	143
[11054eb]	144	__ioarbiter_flush( ctx );
[3c039b0]	145
[dddb3dd0]	146	__STATS__( true, io.calls.flush++; )
[c7b2215]	147	int ret = syscall( __NR_io_uring_enter, ctx.fd, ctx.sq.to_submit, min_comp, min_comp > 0 ? IORING_ENTER_GETEVENTS : 0, (sigset_t *)0p, _NSIG / 8);
[dddb3dd0]	148	if( ret < 0 ) {
	149	switch((int)errno) {
	150	case EAGAIN:
	151	case EINTR:
	152	case EBUSY:
	153	// Update statistics
	154	__STATS__( false, io.calls.errors.busy ++; )
[059ad16]	155	return false;
[dddb3dd0]	156	default:
	157	abort( "KERNEL ERROR: IO_URING SYSCALL - (%d) %s\n", (int)errno, strerror(errno) );
[61dd73d]	158	}
[dddb3dd0]	159	}
[ece0e80]	160
[dddb3dd0]	161	__cfadbg_print_safe(io, "Kernel I/O : %u submitted to io_uring %d\n", ret, ctx.fd);
	162	__STATS__( true, io.calls.submitted += ret; )
	163	/* paranoid / verify( ctx.sq.to_submit <= ctx.sq.num );
	164	/* paranoid */ verify( ctx.sq.to_submit >= ret );
	165
	166	ctx.sq.to_submit -= ret;
[ece0e80]	167
[dddb3dd0]	168	/* paranoid / verify( ctx.sq.to_submit <= ctx.sq.num );
[5dadc9b7]	169
[dddb3dd0]	170	// Release the consumed SQEs
	171	__release_sqes( ctx );
[ece0e80]	172
[dddb3dd0]	173	/* paranoid */ verify( ! __preemption_enabled() );
[61dd73d]	174
[dddb3dd0]	175	ctx.proc->io.pending = false;
[7ef162b2]	176	ready_schedule_lock();
	177	bool ret = __cfa_io_drain( proc );
	178	ready_schedule_unlock();
	179	return ret;
[61dd73d]	180	}
[f6660520]	181
[92976d9]	182	//=============================================================================================
	183	// I/O Submissions
	184	//=============================================================================================
	185
[2d8f7b0]	186	// Submition steps :
[e46c753]	187	// 1 - Allocate a queue entry. The ring already has memory for all entries but only the ones
[2d8f7b0]	188	// listed in sq.array are visible by the kernel. For those not listed, the kernel does not
	189	// offer any assurance that an entry is not being filled by multiple flags. Therefore, we
	190	// need to write an allocator that allows allocating concurrently.
	191	//
[e46c753]	192	// 2 - Actually fill the submit entry, this is the only simple and straightforward step.
[2d8f7b0]	193	//
[e46c753]	194	// 3 - Append the entry index to the array and adjust the tail accordingly. This operation
[2d8f7b0]	195	// needs to arrive to two concensus at the same time:
	196	// A - The order in which entries are listed in the array: no two threads must pick the
	197	// same index for their entries
	198	// B - When can the tail be update for the kernel. EVERY entries in the array between
	199	// head and tail must be fully filled and shouldn't ever be touched again.
	200	//
[78da4ab]	201	//=============================================================================================
	202	// Allocation
	203	// for user's convenience fill the sqes from the indexes
	204	static inline void __fill(struct io_uring_sqe * out_sqes[], __u32 want, __u32 idxs[], struct $io_context * ctx) {
	205	struct io_uring_sqe * sqes = ctx->sq.sqes;
	206	for(i; want) {
[dddb3dd0]	207	__cfadbg_print_safe(io, "Kernel I/O : filling loop\n");
[78da4ab]	208	out_sqes[i] = &sqes[idxs[i]];
	209	}
	210	}
[2489d31]	211
[78da4ab]	212	// Try to directly allocate from the a given context
	213	// Not thread-safe
	214	static inline bool __alloc(struct $io_context * ctx, __u32 idxs[], __u32 want) {
	215	__sub_ring_t & sq = ctx->sq;
	216	const __u32 mask = *sq.mask;
	217	__u32 fhead = sq.free_ring.head; // get the current head of the queue
	218	__u32 ftail = sq.free_ring.tail; // get the current tail of the queue
[2489d31]	219
[78da4ab]	220	// If we don't have enough sqes, fail
	221	if((ftail - fhead) < want) { return false; }
[426f60c]	222
[78da4ab]	223	// copy all the indexes we want from the available list
	224	for(i; want) {
[dddb3dd0]	225	__cfadbg_print_safe(io, "Kernel I/O : allocating loop\n");
[78da4ab]	226	idxs[i] = sq.free_ring.array[(fhead + i) & mask];
[6f121b8]	227	}
[2489d31]	228
[78da4ab]	229	// Advance the head to mark the indexes as consumed
	230	__atomic_store_n(&sq.free_ring.head, fhead + want, __ATOMIC_RELEASE);
[df40a56]	231
[78da4ab]	232	// return success
	233	return true;
	234	}
[df40a56]	235
[78da4ab]	236	// Allocate an submit queue entry.
	237	// The kernel cannot see these entries until they are submitted, but other threads must be
	238	// able to see which entries can be used and which are already un used by an other thread
	239	// for convenience, return both the index and the pointer to the sqe
	240	// sqe == &sqes[idx]
	241	struct $io_context * cfa_io_allocate(struct io_uring_sqe * sqes[], __u32 idxs[], __u32 want) {
	242	__cfadbg_print_safe(io, "Kernel I/O : attempting to allocate %u\n", want);
[df40a56]	243
[78da4ab]	244	disable_interrupts();
	245	processor * proc = __cfaabi_tls.this_processor;
[dddb3dd0]	246	$io_context * ctx = proc->io.ctx;
[78da4ab]	247	/* paranoid */ verify( __cfaabi_tls.this_processor );
[dddb3dd0]	248	/* paranoid */ verify( ctx );
[78da4ab]	249
[dddb3dd0]	250	__cfadbg_print_safe(io, "Kernel I/O : attempting to fast allocation\n");
[78da4ab]	251
[dddb3dd0]	252	// We can proceed to the fast path
	253	if( __alloc(ctx, idxs, want) ) {
	254	// Allocation was successful
	255	__STATS__( true, io.alloc.fast += 1; )
[a3821fa]	256	enable_interrupts();
[df40a56]	257
[dddb3dd0]	258	__cfadbg_print_safe(io, "Kernel I/O : fast allocation successful from ring %d\n", ctx->fd);
[2fafe7e]	259
[dddb3dd0]	260	__fill( sqes, want, idxs, ctx );
	261	return ctx;
[df40a56]	262	}
[dddb3dd0]	263	// The fast path failed, fallback
	264	__STATS__( true, io.alloc.fail += 1; )
[df40a56]	265
[78da4ab]	266	// Fast path failed, fallback on arbitration
[d60d30e]	267	__STATS__( true, io.alloc.slow += 1; )
[a3821fa]	268	enable_interrupts();
[78da4ab]	269
[dddb3dd0]	270	$io_arbiter * ioarb = proc->cltr->io.arbiter;
	271	/* paranoid */ verify( ioarb );
	272
[78da4ab]	273	__cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for allocation\n");
	274
[11054eb]	275	struct $io_context * ret = __ioarbiter_allocate(*ioarb, idxs, want);
[78da4ab]	276
[dddb3dd0]	277	__cfadbg_print_safe(io, "Kernel I/O : slow allocation completed from ring %d\n", ret->fd);
[df40a56]	278
[78da4ab]	279	__fill( sqes, want, idxs,ret );
	280	return ret;
[df40a56]	281	}
	282
[78da4ab]	283	//=============================================================================================
	284	// submission
[dddb3dd0]	285	static inline void __submit( struct $io_context * ctx, __u32 idxs[], __u32 have, bool lazy) {
[78da4ab]	286	// We can proceed to the fast path
	287	// Get the right objects
	288	__sub_ring_t & sq = ctx->sq;
	289	const __u32 mask = *sq.mask;
[dddb3dd0]	290	__u32 tail = *sq.kring.tail;
[78da4ab]	291
	292	// Add the sqes to the array
	293	for( i; have ) {
[dddb3dd0]	294	__cfadbg_print_safe(io, "Kernel I/O : __submit loop\n");
[78da4ab]	295	sq.kring.array[ (tail + i) & mask ] = idxs[i];
[426f60c]	296	}
	297
[78da4ab]	298	// Make the sqes visible to the submitter
[dddb3dd0]	299	__atomic_store_n(sq.kring.tail, tail + have, __ATOMIC_RELEASE);
[e8ac228]	300	sq.to_submit += have;
[426f60c]	301
[dddb3dd0]	302	ctx->proc->io.pending = true;
	303	ctx->proc->io.dirty = true;
	304	if(sq.to_submit > 30 \|\| !lazy) {
[c7b2215]	305	__cfa_io_flush( ctx->proc, 0 );
[dddb3dd0]	306	}
[78da4ab]	307	}
[2489d31]	308
[dddb3dd0]	309	void cfa_io_submit( struct $io_context * inctx, __u32 idxs[], __u32 have, bool lazy ) __attribute__((nonnull (1))) {
	310	__cfadbg_print_safe(io, "Kernel I/O : attempting to submit %u (%s)\n", have, lazy ? "lazy" : "eager");
[5dadc9b7]	311
[78da4ab]	312	disable_interrupts();
	313	processor * proc = __cfaabi_tls.this_processor;
	314	$io_context * ctx = proc->io.ctx;
[dddb3dd0]	315	/* paranoid */ verify( __cfaabi_tls.this_processor );
	316	/* paranoid */ verify( ctx );
[e46c753]	317
[78da4ab]	318	// Can we proceed to the fast path
[dddb3dd0]	319	if( ctx == inctx ) // We have the right instance?
[78da4ab]	320	{
[dddb3dd0]	321	__submit(ctx, idxs, have, lazy);
[e46c753]	322
[78da4ab]	323	// Mark the instance as no longer in-use, re-enable interrupts and return
[d60d30e]	324	__STATS__( true, io.submit.fast += 1; )
[a3821fa]	325	enable_interrupts();
[ece0e80]	326
[78da4ab]	327	__cfadbg_print_safe(io, "Kernel I/O : submitted on fast path\n");
	328	return;
[e46c753]	329	}
[d384787]	330
[78da4ab]	331	// Fast path failed, fallback on arbitration
[d60d30e]	332	__STATS__( true, io.submit.slow += 1; )
[a3821fa]	333	enable_interrupts();
[5dadc9b7]	334
[78da4ab]	335	__cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for submission\n");
[426f60c]	336
[11054eb]	337	__ioarbiter_submit(inctx, idxs, have, lazy);
[78da4ab]	338	}
[2fab24e3]	339
[78da4ab]	340	//=============================================================================================
	341	// Flushing
[426f60c]	342	// Go through the ring's submit queue and release everything that has already been consumed
	343	// by io_uring
[78da4ab]	344	// This cannot be done by multiple threads
	345	static __u32 __release_sqes( struct $io_context & ctx ) {
	346	const __u32 mask = *ctx.sq.mask;
[732b406]	347
[426f60c]	348	__attribute__((unused))
[78da4ab]	349	__u32 ctail = *ctx.sq.kring.tail; // get the current tail of the queue
	350	__u32 chead = *ctx.sq.kring.head; // get the current head of the queue
	351	__u32 phead = ctx.sq.kring.released; // get the head the last time we were here
	352
	353	__u32 ftail = ctx.sq.free_ring.tail; // get the current tail of the queue
[732b406]	354
[426f60c]	355	// the 3 fields are organized like this diagram
	356	// except it's are ring
	357	// ---+--------+--------+----
	358	// ---+--------+--------+----
	359	// ^ ^ ^
	360	// phead chead ctail
	361
	362	// make sure ctail doesn't wrap around and reach phead
	363	/* paranoid */ verify(
	364	(ctail >= chead && chead >= phead)
	365	\|\| (chead >= phead && phead >= ctail)
	366	\|\| (phead >= ctail && ctail >= chead)
	367	);
	368
	369	// find the range we need to clear
[4998155]	370	__u32 count = chead - phead;
[426f60c]	371
[78da4ab]	372	if(count == 0) {
	373	return 0;
	374	}
	375
[426f60c]	376	// We acquired an previous-head/current-head range
	377	// go through the range and release the sqes
[34b61882]	378	for( i; count ) {
[dddb3dd0]	379	__cfadbg_print_safe(io, "Kernel I/O : release loop\n");
[78da4ab]	380	__u32 idx = ctx.sq.kring.array[ (phead + i) & mask ];
	381	ctx.sq.free_ring.array[ (ftail + i) & mask ] = idx;
[34b61882]	382	}
[78da4ab]	383
	384	ctx.sq.kring.released = chead; // note up to were we processed
	385	__atomic_store_n(&ctx.sq.free_ring.tail, ftail + count, __ATOMIC_SEQ_CST);
	386
	387	__ioarbiter_notify(ctx);
	388
[34b61882]	389	return count;
	390	}
[35285fd]	391
[78da4ab]	392	//=============================================================================================
	393	// I/O Arbiter
	394	//=============================================================================================
[11054eb]	395	static inline void block(__outstanding_io_queue & queue, __outstanding_io & item) {
	396	// Lock the list, it's not thread safe
	397	lock( queue.lock __cfaabi_dbg_ctx2 );
	398	{
	399	// Add our request to the list
	400	add( queue.queue, item );
	401
	402	// Mark as pending
	403	__atomic_store_n( &queue.empty, false, __ATOMIC_SEQ_CST );
	404	}
	405	unlock( queue.lock );
	406
	407	wait( item.sem );
	408	}
	409
	410	static inline bool empty(__outstanding_io_queue & queue ) {
	411	return __atomic_load_n( &queue.empty, __ATOMIC_SEQ_CST);
	412	}
	413
	414	static $io_context * __ioarbiter_allocate( $io_arbiter & this, __u32 idxs[], __u32 want ) {
[78da4ab]	415	__cfadbg_print_safe(io, "Kernel I/O : arbiter allocating\n");
	416
[d60d30e]	417	__STATS__( false, io.alloc.block += 1; )
	418
[78da4ab]	419	// No one has any resources left, wait for something to finish
[11054eb]	420	// We need to add ourself to a list of pending allocs and wait for an answer
	421	__pending_alloc pa;
	422	pa.idxs = idxs;
	423	pa.want = want;
[78da4ab]	424
[11054eb]	425	block(this.pending, (__outstanding_io&)pa);
[78da4ab]	426
[11054eb]	427	return pa.ctx;
[dddb3dd0]	428
[78da4ab]	429	}
	430
[11054eb]	431	static void __ioarbiter_notify( $io_arbiter & this, $io_context * ctx ) {
	432	/* paranoid */ verify( !empty(this.pending.queue) );
[78da4ab]	433
[11054eb]	434	lock( this.pending.lock __cfaabi_dbg_ctx2 );
	435	{
	436	while( !empty(this.pending.queue) ) {
	437	__cfadbg_print_safe(io, "Kernel I/O : notifying\n");
	438	__u32 have = ctx->sq.free_ring.tail - ctx->sq.free_ring.head;
	439	__pending_alloc & pa = (__pending_alloc&)head( this.pending.queue );
[78da4ab]	440
[11054eb]	441	if( have > pa.want ) goto DONE;
	442	drop( this.pending.queue );
[78da4ab]	443
[11054eb]	444	/* paranoid */__attribute__((unused)) bool ret =
[78da4ab]	445
[11054eb]	446	__alloc(ctx, pa.idxs, pa.want);
	447
	448	/* paranoid */ verify( ret );
	449
	450	pa.ctx = ctx;
	451
	452	post( pa.sem );
	453	}
	454
	455	this.pending.empty = true;
	456	DONE:;
	457	}
	458	unlock( this.pending.lock );
[78da4ab]	459	}
	460
	461	static void __ioarbiter_notify( $io_context & ctx ) {
[11054eb]	462	if(!empty( ctx.arbiter->pending )) {
[78da4ab]	463	__ioarbiter_notify( *ctx.arbiter, &ctx );
	464	}
	465	}
	466
	467	// Simply append to the pending
[11054eb]	468	static void __ioarbiter_submit( $io_context * ctx, __u32 idxs[], __u32 have, bool lazy ) {
[78da4ab]	469	__cfadbg_print_safe(io, "Kernel I/O : submitting %u from the arbiter to context %u\n", have, ctx->fd);
	470
	471	__cfadbg_print_safe(io, "Kernel I/O : waiting to submit %u\n", have);
	472
[11054eb]	473	__external_io ei;
	474	ei.idxs = idxs;
	475	ei.have = have;
	476	ei.lazy = lazy;
[78da4ab]	477
[11054eb]	478	block(ctx->ext_sq, (__outstanding_io&)ei);
[78da4ab]	479
	480	__cfadbg_print_safe(io, "Kernel I/O : %u submitted from arbiter\n", have);
	481	}
	482
[11054eb]	483	static void __ioarbiter_flush( $io_context & ctx ) {
	484	if(!empty( ctx.ext_sq )) {
	485	__STATS__( false, io.flush.external += 1; )
[78da4ab]	486
[11054eb]	487	__cfadbg_print_safe(io, "Kernel I/O : arbiter flushing\n");
[d60d30e]	488
[11054eb]	489	lock( ctx.ext_sq.lock __cfaabi_dbg_ctx2 );
	490	{
	491	while( !empty(ctx.ext_sq.queue) ) {
	492	__external_io & ei = (__external_io&)drop( ctx.ext_sq.queue );
[78da4ab]	493
[11054eb]	494	__submit(&ctx, ei.idxs, ei.have, ei.lazy);
[78da4ab]	495
[11054eb]	496	post( ei.sem );
	497	}
	498
	499	ctx.ext_sq.empty = true;
	500	}
	501	unlock(ctx.ext_sq.lock );
	502	}
[78da4ab]	503	}
[7ef162b2]	504
[d3605f8]	505	#if defined(CFA_WITH_IO_URING_IDLE)
	506	bool __kernel_read(processor * proc, io_future_t & future, iovec & iov, int fd) {
[6ddef36]	507	$io_context * ctx = proc->io.ctx;
	508	/* paranoid */ verify( ! __preemption_enabled() );
	509	/* paranoid */ verify( proc == __cfaabi_tls.this_processor );
	510	/* paranoid */ verify( ctx );
[7ef162b2]	511
[6ddef36]	512	__u32 idx;
	513	struct io_uring_sqe * sqe;
[7ef162b2]	514
[6ddef36]	515	// We can proceed to the fast path
	516	if( !__alloc(ctx, &idx, 1) ) return false;
	517
	518	// Allocation was successful
	519	__fill( &sqe, 1, &idx, ctx );
	520
	521	sqe->user_data = (uintptr_t)&future;
	522	sqe->flags = 0;
[a1f3d93]	523	sqe->fd = fd;
[6ddef36]	524	sqe->off = 0;
[d3605f8]	525	sqe->ioprio = 0;
[6ddef36]	526	sqe->fsync_flags = 0;
	527	sqe->__pad2[0] = 0;
	528	sqe->__pad2[1] = 0;
	529	sqe->__pad2[2] = 0;
[d3605f8]	530
	531	#if defined(CFA_HAVE_IORING_OP_READ)
	532	sqe->opcode = IORING_OP_READ;
	533	sqe->addr = (uint64_t)iov.iov_base;
	534	sqe->len = iov.iov_len;
	535	#elif defined(CFA_HAVE_READV) && defined(CFA_HAVE_IORING_OP_READV)
	536	sqe->opcode = IORING_OP_READV;
	537	sqe->addr = (uintptr_t)&iov;
	538	sqe->len = 1;
	539	#else
	540	#error CFA_WITH_IO_URING_IDLE but none of CFA_HAVE_READV, CFA_HAVE_IORING_OP_READV or CFA_HAVE_IORING_OP_READ defined
	541	#endif
[6ddef36]	542
	543	asm volatile("": : :"memory");
	544
	545	/* paranoid */ verify( sqe->user_data == (uintptr_t)&future );
	546	__submit( ctx, &idx, 1, true );
	547
	548	/* paranoid */ verify( proc == __cfaabi_tls.this_processor );
	549	/* paranoid */ verify( ! __preemption_enabled() );
[078fb05]	550
	551	return true;
[6ddef36]	552	}
	553	#endif
[47746a2]	554	#endif

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