| Message ID | 20230802231442.275558-6-axboe@kernel.dk (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/5] exit: abtract out should_wake helper for child_wait_callback() | expand |
On Wed, Aug 02, 2023 at 05:14:42PM -0600, Jens Axboe wrote: > This adds support for an async version of waitid(2), in a fully async > version. If an event isn't immediately available, wait for a callback > to trigger a retry. > > The format of the sqe is as follows: > > sqe->len The 'which', the idtype being queried/waited for. > sqe->fd The 'pid' (or id) being waited for. > sqe->file_index The 'options' being set. > sqe->addr2 A pointer to siginfo_t, if any, being filled in. > > buf_index, add3, and waitid_flags are reserved/unused for now. > waitid_flags will be used for options for this request type. One > interesting use case may be to add multi-shot support, so that the > request stays armed and posts a notification every time a monitored > process state change occurs. > > Note that this does not support rusage, on Arnd's recommendation. > > See the waitid(2) man page for details on the arguments. > > Signed-off-by: Jens Axboe <axboe@kernel.dk> > --- > include/linux/io_uring_types.h | 2 + > include/uapi/linux/io_uring.h | 2 + > io_uring/Makefile | 2 +- > io_uring/cancel.c | 5 + > io_uring/io_uring.c | 3 + > io_uring/opdef.c | 9 + > io_uring/waitid.c | 313 +++++++++++++++++++++++++++++++++ > io_uring/waitid.h | 15 ++ > 8 files changed, 350 insertions(+), 1 deletion(-) > create mode 100644 io_uring/waitid.c > create mode 100644 io_uring/waitid.h > > diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h > index a7f03d8d879f..598553877fc2 100644 > --- a/include/linux/io_uring_types.h > +++ b/include/linux/io_uring_types.h > @@ -276,6 +276,8 @@ struct io_ring_ctx { > struct hlist_head futex_list; > struct io_alloc_cache futex_cache; > > + struct hlist_head waitid_list; > + > const struct cred *sq_creds; /* cred used for __io_sq_thread() */ > struct io_sq_data *sq_data; /* if using sq thread polling */ > > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h > index 420f38675769..8fca2cffc343 100644 > --- a/include/uapi/linux/io_uring.h > +++ b/include/uapi/linux/io_uring.h > @@ -66,6 +66,7 @@ struct io_uring_sqe { > __u32 msg_ring_flags; > __u32 uring_cmd_flags; > __u32 futex_flags; > + __u32 waitid_flags; > }; > __u64 user_data; /* data to be passed back at completion time */ > /* pack this to avoid bogus arm OABI complaints */ > @@ -239,6 +240,7 @@ enum io_uring_op { > IORING_OP_FUTEX_WAIT, > IORING_OP_FUTEX_WAKE, > IORING_OP_FUTEX_WAITV, > + IORING_OP_WAITID, > > /* this goes last, obviously */ > IORING_OP_LAST, > diff --git a/io_uring/Makefile b/io_uring/Makefile > index 2e4779bc550c..e5be47e4fc3b 100644 > --- a/io_uring/Makefile > +++ b/io_uring/Makefile > @@ -8,6 +8,6 @@ obj-$(CONFIG_IO_URING) += io_uring.o xattr.o nop.o fs.o splice.o \ > statx.o net.o msg_ring.o timeout.o \ > sqpoll.o fdinfo.o tctx.o poll.o \ > cancel.o kbuf.o rsrc.o rw.o opdef.o \ > - notif.o > + notif.o waitid.o > obj-$(CONFIG_IO_WQ) += io-wq.o > obj-$(CONFIG_FUTEX) += futex.o > diff --git a/io_uring/cancel.c b/io_uring/cancel.c > index 3dba8ccb1cd8..a01f3f41012b 100644 > --- a/io_uring/cancel.c > +++ b/io_uring/cancel.c > @@ -16,6 +16,7 @@ > #include "poll.h" > #include "timeout.h" > #include "futex.h" > +#include "waitid.h" > #include "cancel.h" > > struct io_cancel { > @@ -124,6 +125,10 @@ int io_try_cancel(struct io_uring_task *tctx, struct io_cancel_data *cd, > if (ret != -ENOENT) > return ret; > > + ret = io_waitid_cancel(ctx, cd, issue_flags); > + if (ret != -ENOENT) > + return ret; > + > spin_lock(&ctx->completion_lock); > if (!(cd->flags & IORING_ASYNC_CANCEL_FD)) > ret = io_timeout_cancel(ctx, cd); > diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c > index e52cbdcb29b8..94147e0835bf 100644 > --- a/io_uring/io_uring.c > +++ b/io_uring/io_uring.c > @@ -93,6 +93,7 @@ > #include "net.h" > #include "notif.h" > #include "futex.h" > +#include "waitid.h" > > #include "timeout.h" > #include "poll.h" > @@ -352,6 +353,7 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p) > ctx->submit_state.free_list.next = NULL; > INIT_WQ_LIST(&ctx->locked_free_list); > INIT_HLIST_HEAD(&ctx->futex_list); > + INIT_HLIST_HEAD(&ctx->waitid_list); > INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func); > INIT_WQ_LIST(&ctx->submit_state.compl_reqs); > return ctx; > @@ -3286,6 +3288,7 @@ static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx, > mutex_lock(&ctx->uring_lock); > ret |= io_poll_remove_all(ctx, task, cancel_all); > ret |= io_futex_remove_all(ctx, task, cancel_all); > + ret |= io_waitid_remove_all(ctx, task, cancel_all); > mutex_unlock(&ctx->uring_lock); > ret |= io_kill_timeouts(ctx, task, cancel_all); > if (task) > diff --git a/io_uring/opdef.c b/io_uring/opdef.c > index b9e1e12cac9c..1c5cfa9d7b31 100644 > --- a/io_uring/opdef.c > +++ b/io_uring/opdef.c > @@ -34,6 +34,7 @@ > #include "cancel.h" > #include "rw.h" > #include "futex.h" > +#include "waitid.h" > > static int io_no_issue(struct io_kiocb *req, unsigned int issue_flags) > { > @@ -453,6 +454,10 @@ const struct io_issue_def io_issue_defs[] = { > .prep = io_eopnotsupp_prep, > #endif > }, > + [IORING_OP_WAITID] = { > + .prep = io_waitid_prep, > + .issue = io_waitid, > + }, > }; > > const struct io_cold_def io_cold_defs[] = { > @@ -681,6 +686,10 @@ const struct io_cold_def io_cold_defs[] = { > [IORING_OP_FUTEX_WAITV] = { > .name = "FUTEX_WAITV", > }, > + [IORING_OP_WAITID] = { > + .name = "WAITID", > + .async_size = sizeof(struct io_waitid_async), > + }, > }; > > const char *io_uring_get_opcode(u8 opcode) > diff --git a/io_uring/waitid.c b/io_uring/waitid.c > new file mode 100644 > index 000000000000..14ffa07e161a > --- /dev/null > +++ b/io_uring/waitid.c > @@ -0,0 +1,313 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Support for async notification of waitid > + */ > +#include <linux/kernel.h> > +#include <linux/errno.h> > +#include <linux/fs.h> > +#include <linux/file.h> > +#include <linux/compat.h> > +#include <linux/io_uring.h> > + > +#include <uapi/linux/io_uring.h> > + > +#include "io_uring.h" > +#include "cancel.h" > +#include "waitid.h" > +#include "../kernel/exit.h" > + > +struct io_waitid { > + struct file *file; > + int which; > + pid_t upid; > + int options; > + struct wait_queue_head *head; > + struct siginfo __user *infop; > + struct waitid_info info; > +}; > + > +static void io_waitid_free(struct io_kiocb *req) > +{ > + struct io_waitid_async *iwa = req->async_data; > + > + put_pid(iwa->wo.wo_pid); > + kfree(req->async_data); > + req->async_data = NULL; > + req->flags &= ~REQ_F_ASYNC_DATA; > +} > + > +#ifdef CONFIG_COMPAT > +static bool io_waitid_compat_copy_si(struct io_waitid *iw, int signo) > +{ > + struct compat_siginfo __user *infop; > + bool ret; > + > + infop = (struct compat_siginfo __user *) iw->infop; > + > + if (!user_write_access_begin(infop, sizeof(*infop))) > + return false; > + > + unsafe_put_user(signo, &infop->si_signo, Efault); > + unsafe_put_user(0, &infop->si_errno, Efault); > + unsafe_put_user(iw->info.cause, &infop->si_code, Efault); > + unsafe_put_user(iw->info.pid, &infop->si_pid, Efault); > + unsafe_put_user(iw->info.uid, &infop->si_uid, Efault); > + unsafe_put_user(iw->info.status, &infop->si_status, Efault); > + ret = true; > +done: > + user_write_access_end(); > + return ret; > +Efault: > + ret = false; > + goto done; > +} > +#endif > + > +static bool io_waitid_copy_si(struct io_kiocb *req, int signo) > +{ > + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); > + bool ret; > + > + if (!iw->infop) > + return true; > + > +#ifdef CONFIG_COMPAT > + if (req->ctx->compat) > + return io_waitid_compat_copy_si(iw, signo); > +#endif > + > + if (!user_write_access_begin(iw->infop, sizeof(*iw->infop))) > + return false; > + > + unsafe_put_user(signo, &iw->infop->si_signo, Efault); > + unsafe_put_user(0, &iw->infop->si_errno, Efault); > + unsafe_put_user(iw->info.cause, &iw->infop->si_code, Efault); > + unsafe_put_user(iw->info.pid, &iw->infop->si_pid, Efault); > + unsafe_put_user(iw->info.uid, &iw->infop->si_uid, Efault); > + unsafe_put_user(iw->info.status, &iw->infop->si_status, Efault); > + ret = true; > +done: > + user_write_access_end(); > + return ret; > +Efault: > + ret = false; > + goto done; > +} > + > +static int io_waitid_finish(struct io_kiocb *req, int ret) > +{ > + int signo = 0; > + > + if (ret > 0) { > + signo = SIGCHLD; > + ret = 0; > + } > + > + if (!io_waitid_copy_si(req, signo)) > + ret = -EFAULT; > + io_waitid_free(req); > + return ret; > +} > + > +static void io_waitid_complete(struct io_kiocb *req, int ret) > +{ > + struct io_tw_state ts = { .locked = true }; > + > + lockdep_assert_held(&req->ctx->uring_lock); > + > + /* > + * Did cancel find it meanwhile? > + */ > + if (hlist_unhashed(&req->hash_node)) > + return; > + > + hlist_del_init(&req->hash_node); > + > + ret = io_waitid_finish(req, ret); > + if (ret < 0) > + req_set_fail(req); > + io_req_set_res(req, ret, 0); > + io_req_task_complete(req, &ts); > +} > + > +static bool __io_waitid_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req) > +{ > + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); > + struct wait_queue_head *head; > + > + head = READ_ONCE(iw->head); > + if (head) { > + struct io_waitid_async *iwa = req->async_data; > + > + spin_lock_irq(&head->lock); > + list_del_init(&iwa->wo.child_wait.entry); > + iw->head = NULL; > + spin_unlock_irq(&head->lock); > + io_waitid_complete(req, -ECANCELED); > + return true; > + } > + > + return false; > +} > + > +int io_waitid_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd, > + unsigned int issue_flags) > +{ > + struct hlist_node *tmp; > + struct io_kiocb *req; > + int nr = 0; > + > + if (cd->flags & (IORING_ASYNC_CANCEL_FD|IORING_ASYNC_CANCEL_FD_FIXED)) > + return -ENOENT; > + > + io_ring_submit_lock(ctx, issue_flags); > + hlist_for_each_entry_safe(req, tmp, &ctx->waitid_list, hash_node) { > + if (req->cqe.user_data != cd->data && > + !(cd->flags & IORING_ASYNC_CANCEL_ANY)) > + continue; > + if (__io_waitid_cancel(ctx, req)) > + nr++; > + if (!(cd->flags & IORING_ASYNC_CANCEL_ALL)) > + break; > + } > + io_ring_submit_unlock(ctx, issue_flags); > + > + if (nr) > + return nr; > + > + return -ENOENT; > +} > + > +bool io_waitid_remove_all(struct io_ring_ctx *ctx, struct task_struct *task, > + bool cancel_all) > +{ > + struct hlist_node *tmp; > + struct io_kiocb *req; > + bool found = false; > + > + lockdep_assert_held(&ctx->uring_lock); > + > + hlist_for_each_entry_safe(req, tmp, &ctx->waitid_list, hash_node) { > + if (!io_match_task_safe(req, task, cancel_all)) > + continue; > + __io_waitid_cancel(ctx, req); > + found = true; > + } > + > + return found; > +} > + > +static void io_waitid_cb(struct io_kiocb *req, struct io_tw_state *ts) > +{ > + struct io_waitid_async *iwa = req->async_data; > + struct io_ring_ctx *ctx = req->ctx; > + int ret; > + > + /* > + * If we get -ERESTARTSYS here, we need to re-arm and check again > + * to ensure we get another callback. If the retry works, then we can > + * just remove ourselves from the waitqueue again and finish the > + * request. > + */ > + ret = __do_wait(&iwa->wo); > + if (unlikely(ret == -ERESTARTSYS)) { > + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); > + > + io_tw_lock(ctx, ts); > + iw->head = ¤t->signal->wait_chldexit; > + add_wait_queue(iw->head, &iwa->wo.child_wait); > + ret = __do_wait(&iwa->wo); > + if (ret == -ERESTARTSYS) > + return; > + > + remove_wait_queue(iw->head, &iwa->wo.child_wait); > + iw->head = NULL; > + } > + > + io_tw_lock(ctx, ts); > + io_waitid_complete(req, ret); > +} > + > +static int io_waitid_wait(struct wait_queue_entry *wait, unsigned mode, > + int sync, void *key) > +{ > + struct wait_opts *wo = container_of(wait, struct wait_opts, child_wait); > + struct io_waitid_async *iwa = container_of(wo, struct io_waitid_async, wo); > + struct io_kiocb *req = iwa->req; > + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); > + struct task_struct *p = key; > + > + if (!pid_child_should_wake(wo, p)) > + return 0; > + > + req->io_task_work.func = io_waitid_cb; > + io_req_task_work_add(req); > + iw->head = NULL; > + list_del_init(&wait->entry); > + return 1; > +} > + > +int io_waitid_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) > +{ > + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); > + > + if (sqe->addr || sqe->buf_index || sqe->addr3 || sqe->waitid_flags) > + return -EINVAL; > + > + iw->which = READ_ONCE(sqe->len); > + iw->options = READ_ONCE(sqe->file_index); > + iw->upid = READ_ONCE(sqe->fd); > + iw->infop = u64_to_user_ptr(READ_ONCE(sqe->addr2)); > + iw->head = NULL; > + return 0; > +} > + > +int io_waitid(struct io_kiocb *req, unsigned int issue_flags) > +{ > + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); > + struct io_ring_ctx *ctx = req->ctx; > + struct io_waitid_async *iwa; > + unsigned int f_flags = 0; > + int ret; > + > + if (io_alloc_async_data(req)) > + return -ENOMEM; > + > + iwa = req->async_data; > + iwa->req = req; > + > + ret = kernel_waitid_prepare(&iwa->wo, iw->which, iw->upid, &iw->info, > + iw->options, NULL, &f_flags); It seems you're not really using @f_flags at all so I'd just not bother exposing it in kernel_waitid_prepare(). I think the following (untested) will let you avoid all this: diff --git a/kernel/exit.c b/kernel/exit.c index 1c9d1cbadcd0..33eba306aa51 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1646,10 +1646,11 @@ static long do_wait(struct wait_opts *wo) int kernel_waitid_prepare(struct wait_opts *wo, int which, pid_t upid, struct waitid_info *infop, int options, - struct rusage *ru, unsigned int *f_flags) + struct rusage *ru) { struct pid *pid = NULL; enum pid_type type; + unsigned int f_flags = 0; if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED| __WNOTHREAD|__WCLONE|__WALL)) @@ -1708,16 +1709,16 @@ static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop, { struct wait_opts wo; long ret; - unsigned int f_flags = 0; - ret = kernel_waitid_prepare(&wo, which, upid, infop, options, ru, - &f_flags); + ret = kernel_waitid_prepare(&wo, which, upid, infop, options, ru); if (ret) return ret; ret = do_wait(&wo); - if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK)) + if (!ret && !(options & WNOHANG) && (wo.wo_flags & WNOHANG)) { + WARN_ON_ONCE(which != P_PIDFD); ret = -EAGAIN; + } put_pid(wo.wo_pid); return ret; diff --git a/kernel/exit.h b/kernel/exit.h index f10207ba1341..278faa26a653 100644 --- a/kernel/exit.h +++ b/kernel/exit.h @@ -26,5 +26,5 @@ bool pid_child_should_wake(struct wait_opts *wo, struct task_struct *p); long __do_wait(struct wait_opts *wo); int kernel_waitid_prepare(struct wait_opts *wo, int which, pid_t upid, struct waitid_info *infop, int options, - struct rusage *ru, unsigned int *f_flags); + struct rusage *ru); #endif
On 8/9/23 5:27 AM, Christian Brauner wrote: >> +int io_waitid(struct io_kiocb *req, unsigned int issue_flags) >> +{ >> + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); >> + struct io_ring_ctx *ctx = req->ctx; >> + struct io_waitid_async *iwa; >> + unsigned int f_flags = 0; >> + int ret; >> + >> + if (io_alloc_async_data(req)) >> + return -ENOMEM; >> + >> + iwa = req->async_data; >> + iwa->req = req; >> + >> + ret = kernel_waitid_prepare(&iwa->wo, iw->which, iw->upid, &iw->info, >> + iw->options, NULL, &f_flags); > > It seems you're not really using @f_flags at all so I'd just not bother > exposing it in kernel_waitid_prepare(). I think the following (untested) > will let you avoid all this: That's a good idea, I'll update it to get rid of the f_flags. Thanks!
diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h index a7f03d8d879f..598553877fc2 100644 --- a/include/linux/io_uring_types.h +++ b/include/linux/io_uring_types.h @@ -276,6 +276,8 @@ struct io_ring_ctx { struct hlist_head futex_list; struct io_alloc_cache futex_cache; + struct hlist_head waitid_list; + const struct cred *sq_creds; /* cred used for __io_sq_thread() */ struct io_sq_data *sq_data; /* if using sq thread polling */ diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h index 420f38675769..8fca2cffc343 100644 --- a/include/uapi/linux/io_uring.h +++ b/include/uapi/linux/io_uring.h @@ -66,6 +66,7 @@ struct io_uring_sqe { __u32 msg_ring_flags; __u32 uring_cmd_flags; __u32 futex_flags; + __u32 waitid_flags; }; __u64 user_data; /* data to be passed back at completion time */ /* pack this to avoid bogus arm OABI complaints */ @@ -239,6 +240,7 @@ enum io_uring_op { IORING_OP_FUTEX_WAIT, IORING_OP_FUTEX_WAKE, IORING_OP_FUTEX_WAITV, + IORING_OP_WAITID, /* this goes last, obviously */ IORING_OP_LAST, diff --git a/io_uring/Makefile b/io_uring/Makefile index 2e4779bc550c..e5be47e4fc3b 100644 --- a/io_uring/Makefile +++ b/io_uring/Makefile @@ -8,6 +8,6 @@ obj-$(CONFIG_IO_URING) += io_uring.o xattr.o nop.o fs.o splice.o \ statx.o net.o msg_ring.o timeout.o \ sqpoll.o fdinfo.o tctx.o poll.o \ cancel.o kbuf.o rsrc.o rw.o opdef.o \ - notif.o + notif.o waitid.o obj-$(CONFIG_IO_WQ) += io-wq.o obj-$(CONFIG_FUTEX) += futex.o diff --git a/io_uring/cancel.c b/io_uring/cancel.c index 3dba8ccb1cd8..a01f3f41012b 100644 --- a/io_uring/cancel.c +++ b/io_uring/cancel.c @@ -16,6 +16,7 @@ #include "poll.h" #include "timeout.h" #include "futex.h" +#include "waitid.h" #include "cancel.h" struct io_cancel { @@ -124,6 +125,10 @@ int io_try_cancel(struct io_uring_task *tctx, struct io_cancel_data *cd, if (ret != -ENOENT) return ret; + ret = io_waitid_cancel(ctx, cd, issue_flags); + if (ret != -ENOENT) + return ret; + spin_lock(&ctx->completion_lock); if (!(cd->flags & IORING_ASYNC_CANCEL_FD)) ret = io_timeout_cancel(ctx, cd); diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index e52cbdcb29b8..94147e0835bf 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -93,6 +93,7 @@ #include "net.h" #include "notif.h" #include "futex.h" +#include "waitid.h" #include "timeout.h" #include "poll.h" @@ -352,6 +353,7 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p) ctx->submit_state.free_list.next = NULL; INIT_WQ_LIST(&ctx->locked_free_list); INIT_HLIST_HEAD(&ctx->futex_list); + INIT_HLIST_HEAD(&ctx->waitid_list); INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func); INIT_WQ_LIST(&ctx->submit_state.compl_reqs); return ctx; @@ -3286,6 +3288,7 @@ static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx, mutex_lock(&ctx->uring_lock); ret |= io_poll_remove_all(ctx, task, cancel_all); ret |= io_futex_remove_all(ctx, task, cancel_all); + ret |= io_waitid_remove_all(ctx, task, cancel_all); mutex_unlock(&ctx->uring_lock); ret |= io_kill_timeouts(ctx, task, cancel_all); if (task) diff --git a/io_uring/opdef.c b/io_uring/opdef.c index b9e1e12cac9c..1c5cfa9d7b31 100644 --- a/io_uring/opdef.c +++ b/io_uring/opdef.c @@ -34,6 +34,7 @@ #include "cancel.h" #include "rw.h" #include "futex.h" +#include "waitid.h" static int io_no_issue(struct io_kiocb *req, unsigned int issue_flags) { @@ -453,6 +454,10 @@ const struct io_issue_def io_issue_defs[] = { .prep = io_eopnotsupp_prep, #endif }, + [IORING_OP_WAITID] = { + .prep = io_waitid_prep, + .issue = io_waitid, + }, }; const struct io_cold_def io_cold_defs[] = { @@ -681,6 +686,10 @@ const struct io_cold_def io_cold_defs[] = { [IORING_OP_FUTEX_WAITV] = { .name = "FUTEX_WAITV", }, + [IORING_OP_WAITID] = { + .name = "WAITID", + .async_size = sizeof(struct io_waitid_async), + }, }; const char *io_uring_get_opcode(u8 opcode) diff --git a/io_uring/waitid.c b/io_uring/waitid.c new file mode 100644 index 000000000000..14ffa07e161a --- /dev/null +++ b/io_uring/waitid.c @@ -0,0 +1,313 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Support for async notification of waitid + */ +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/fs.h> +#include <linux/file.h> +#include <linux/compat.h> +#include <linux/io_uring.h> + +#include <uapi/linux/io_uring.h> + +#include "io_uring.h" +#include "cancel.h" +#include "waitid.h" +#include "../kernel/exit.h" + +struct io_waitid { + struct file *file; + int which; + pid_t upid; + int options; + struct wait_queue_head *head; + struct siginfo __user *infop; + struct waitid_info info; +}; + +static void io_waitid_free(struct io_kiocb *req) +{ + struct io_waitid_async *iwa = req->async_data; + + put_pid(iwa->wo.wo_pid); + kfree(req->async_data); + req->async_data = NULL; + req->flags &= ~REQ_F_ASYNC_DATA; +} + +#ifdef CONFIG_COMPAT +static bool io_waitid_compat_copy_si(struct io_waitid *iw, int signo) +{ + struct compat_siginfo __user *infop; + bool ret; + + infop = (struct compat_siginfo __user *) iw->infop; + + if (!user_write_access_begin(infop, sizeof(*infop))) + return false; + + unsafe_put_user(signo, &infop->si_signo, Efault); + unsafe_put_user(0, &infop->si_errno, Efault); + unsafe_put_user(iw->info.cause, &infop->si_code, Efault); + unsafe_put_user(iw->info.pid, &infop->si_pid, Efault); + unsafe_put_user(iw->info.uid, &infop->si_uid, Efault); + unsafe_put_user(iw->info.status, &infop->si_status, Efault); + ret = true; +done: + user_write_access_end(); + return ret; +Efault: + ret = false; + goto done; +} +#endif + +static bool io_waitid_copy_si(struct io_kiocb *req, int signo) +{ + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); + bool ret; + + if (!iw->infop) + return true; + +#ifdef CONFIG_COMPAT + if (req->ctx->compat) + return io_waitid_compat_copy_si(iw, signo); +#endif + + if (!user_write_access_begin(iw->infop, sizeof(*iw->infop))) + return false; + + unsafe_put_user(signo, &iw->infop->si_signo, Efault); + unsafe_put_user(0, &iw->infop->si_errno, Efault); + unsafe_put_user(iw->info.cause, &iw->infop->si_code, Efault); + unsafe_put_user(iw->info.pid, &iw->infop->si_pid, Efault); + unsafe_put_user(iw->info.uid, &iw->infop->si_uid, Efault); + unsafe_put_user(iw->info.status, &iw->infop->si_status, Efault); + ret = true; +done: + user_write_access_end(); + return ret; +Efault: + ret = false; + goto done; +} + +static int io_waitid_finish(struct io_kiocb *req, int ret) +{ + int signo = 0; + + if (ret > 0) { + signo = SIGCHLD; + ret = 0; + } + + if (!io_waitid_copy_si(req, signo)) + ret = -EFAULT; + io_waitid_free(req); + return ret; +} + +static void io_waitid_complete(struct io_kiocb *req, int ret) +{ + struct io_tw_state ts = { .locked = true }; + + lockdep_assert_held(&req->ctx->uring_lock); + + /* + * Did cancel find it meanwhile? + */ + if (hlist_unhashed(&req->hash_node)) + return; + + hlist_del_init(&req->hash_node); + + ret = io_waitid_finish(req, ret); + if (ret < 0) + req_set_fail(req); + io_req_set_res(req, ret, 0); + io_req_task_complete(req, &ts); +} + +static bool __io_waitid_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req) +{ + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); + struct wait_queue_head *head; + + head = READ_ONCE(iw->head); + if (head) { + struct io_waitid_async *iwa = req->async_data; + + spin_lock_irq(&head->lock); + list_del_init(&iwa->wo.child_wait.entry); + iw->head = NULL; + spin_unlock_irq(&head->lock); + io_waitid_complete(req, -ECANCELED); + return true; + } + + return false; +} + +int io_waitid_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd, + unsigned int issue_flags) +{ + struct hlist_node *tmp; + struct io_kiocb *req; + int nr = 0; + + if (cd->flags & (IORING_ASYNC_CANCEL_FD|IORING_ASYNC_CANCEL_FD_FIXED)) + return -ENOENT; + + io_ring_submit_lock(ctx, issue_flags); + hlist_for_each_entry_safe(req, tmp, &ctx->waitid_list, hash_node) { + if (req->cqe.user_data != cd->data && + !(cd->flags & IORING_ASYNC_CANCEL_ANY)) + continue; + if (__io_waitid_cancel(ctx, req)) + nr++; + if (!(cd->flags & IORING_ASYNC_CANCEL_ALL)) + break; + } + io_ring_submit_unlock(ctx, issue_flags); + + if (nr) + return nr; + + return -ENOENT; +} + +bool io_waitid_remove_all(struct io_ring_ctx *ctx, struct task_struct *task, + bool cancel_all) +{ + struct hlist_node *tmp; + struct io_kiocb *req; + bool found = false; + + lockdep_assert_held(&ctx->uring_lock); + + hlist_for_each_entry_safe(req, tmp, &ctx->waitid_list, hash_node) { + if (!io_match_task_safe(req, task, cancel_all)) + continue; + __io_waitid_cancel(ctx, req); + found = true; + } + + return found; +} + +static void io_waitid_cb(struct io_kiocb *req, struct io_tw_state *ts) +{ + struct io_waitid_async *iwa = req->async_data; + struct io_ring_ctx *ctx = req->ctx; + int ret; + + /* + * If we get -ERESTARTSYS here, we need to re-arm and check again + * to ensure we get another callback. If the retry works, then we can + * just remove ourselves from the waitqueue again and finish the + * request. + */ + ret = __do_wait(&iwa->wo); + if (unlikely(ret == -ERESTARTSYS)) { + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); + + io_tw_lock(ctx, ts); + iw->head = ¤t->signal->wait_chldexit; + add_wait_queue(iw->head, &iwa->wo.child_wait); + ret = __do_wait(&iwa->wo); + if (ret == -ERESTARTSYS) + return; + + remove_wait_queue(iw->head, &iwa->wo.child_wait); + iw->head = NULL; + } + + io_tw_lock(ctx, ts); + io_waitid_complete(req, ret); +} + +static int io_waitid_wait(struct wait_queue_entry *wait, unsigned mode, + int sync, void *key) +{ + struct wait_opts *wo = container_of(wait, struct wait_opts, child_wait); + struct io_waitid_async *iwa = container_of(wo, struct io_waitid_async, wo); + struct io_kiocb *req = iwa->req; + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); + struct task_struct *p = key; + + if (!pid_child_should_wake(wo, p)) + return 0; + + req->io_task_work.func = io_waitid_cb; + io_req_task_work_add(req); + iw->head = NULL; + list_del_init(&wait->entry); + return 1; +} + +int io_waitid_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); + + if (sqe->addr || sqe->buf_index || sqe->addr3 || sqe->waitid_flags) + return -EINVAL; + + iw->which = READ_ONCE(sqe->len); + iw->options = READ_ONCE(sqe->file_index); + iw->upid = READ_ONCE(sqe->fd); + iw->infop = u64_to_user_ptr(READ_ONCE(sqe->addr2)); + iw->head = NULL; + return 0; +} + +int io_waitid(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_waitid *iw = io_kiocb_to_cmd(req, struct io_waitid); + struct io_ring_ctx *ctx = req->ctx; + struct io_waitid_async *iwa; + unsigned int f_flags = 0; + int ret; + + if (io_alloc_async_data(req)) + return -ENOMEM; + + iwa = req->async_data; + iwa->req = req; + + ret = kernel_waitid_prepare(&iwa->wo, iw->which, iw->upid, &iw->info, + iw->options, NULL, &f_flags); + if (ret) + goto done; + + /* + * Arm our callback and add us to the waitqueue, in case no events + * are available. + */ + init_waitqueue_func_entry(&iwa->wo.child_wait, io_waitid_wait); + iwa->wo.child_wait.private = req->task; + iw->head = ¤t->signal->wait_chldexit; + add_wait_queue(iw->head, &iwa->wo.child_wait); + + io_ring_submit_lock(ctx, issue_flags); + hlist_add_head(&req->hash_node, &ctx->waitid_list); + + ret = __do_wait(&iwa->wo); + if (ret == -ERESTARTSYS) { + io_ring_submit_unlock(ctx, issue_flags); + return IOU_ISSUE_SKIP_COMPLETE; + } + + hlist_del_init(&req->hash_node); + remove_wait_queue(iw->head, &iwa->wo.child_wait); + iw->head = NULL; + ret = io_waitid_finish(req, ret); + + io_ring_submit_unlock(ctx, issue_flags); +done: + if (ret < 0) + req_set_fail(req); + io_req_set_res(req, ret, 0); + return IOU_OK; +} diff --git a/io_uring/waitid.h b/io_uring/waitid.h new file mode 100644 index 000000000000..956a8adafe8c --- /dev/null +++ b/io_uring/waitid.h @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "../kernel/exit.h" + +struct io_waitid_async { + struct io_kiocb *req; + struct wait_opts wo; +}; + +int io_waitid_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe); +int io_waitid(struct io_kiocb *req, unsigned int issue_flags); +int io_waitid_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd, + unsigned int issue_flags); +bool io_waitid_remove_all(struct io_ring_ctx *ctx, struct task_struct *task, + bool cancel_all);
This adds support for an async version of waitid(2), in a fully async version. If an event isn't immediately available, wait for a callback to trigger a retry. The format of the sqe is as follows: sqe->len The 'which', the idtype being queried/waited for. sqe->fd The 'pid' (or id) being waited for. sqe->file_index The 'options' being set. sqe->addr2 A pointer to siginfo_t, if any, being filled in. buf_index, add3, and waitid_flags are reserved/unused for now. waitid_flags will be used for options for this request type. One interesting use case may be to add multi-shot support, so that the request stays armed and posts a notification every time a monitored process state change occurs. Note that this does not support rusage, on Arnd's recommendation. See the waitid(2) man page for details on the arguments. Signed-off-by: Jens Axboe <axboe@kernel.dk> --- include/linux/io_uring_types.h | 2 + include/uapi/linux/io_uring.h | 2 + io_uring/Makefile | 2 +- io_uring/cancel.c | 5 + io_uring/io_uring.c | 3 + io_uring/opdef.c | 9 + io_uring/waitid.c | 313 +++++++++++++++++++++++++++++++++ io_uring/waitid.h | 15 ++ 8 files changed, 350 insertions(+), 1 deletion(-) create mode 100644 io_uring/waitid.c create mode 100644 io_uring/waitid.h