From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- io_uring/futex.c | 356 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 356 insertions(+) create mode 100644 io_uring/futex.c (limited to 'io_uring/futex.c') diff --git a/io_uring/futex.c b/io_uring/futex.c new file mode 100644 index 000000000..eaee14242 --- /dev/null +++ b/io_uring/futex.c @@ -0,0 +1,356 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include + +#include + +#include "../kernel/futex/futex.h" +#include "io_uring.h" +#include "alloc_cache.h" +#include "futex.h" + +struct io_futex { + struct file *file; + void __user *uaddr; + unsigned long futex_val; + unsigned long futex_mask; + u32 futex_flags; + unsigned int futex_nr; + bool futexv_unqueued; +}; + +struct io_futex_data { + struct futex_q q; + struct io_kiocb *req; +}; + +struct io_futexv_data { + unsigned long owned; + struct futex_vector futexv[]; +}; + +#define IO_FUTEX_ALLOC_CACHE_MAX 32 + +bool io_futex_cache_init(struct io_ring_ctx *ctx) +{ + return io_alloc_cache_init(&ctx->futex_cache, IO_FUTEX_ALLOC_CACHE_MAX, + sizeof(struct io_futex_data), 0); +} + +void io_futex_cache_free(struct io_ring_ctx *ctx) +{ + io_alloc_cache_free(&ctx->futex_cache, kfree); +} + +static void __io_futex_complete(struct io_tw_req tw_req, io_tw_token_t tw) +{ + hlist_del_init(&tw_req.req->hash_node); + io_req_task_complete(tw_req, tw); +} + +static void io_futex_complete(struct io_tw_req tw_req, io_tw_token_t tw) +{ + struct io_kiocb *req = tw_req.req; + struct io_ring_ctx *ctx = req->ctx; + + io_tw_lock(ctx, tw); + io_cache_free(&ctx->futex_cache, req->async_data); + io_req_async_data_clear(req, 0); + __io_futex_complete(tw_req, tw); +} + +static void io_futexv_complete(struct io_tw_req tw_req, io_tw_token_t tw) +{ + struct io_kiocb *req = tw_req.req; + struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); + struct io_futexv_data *ifd = req->async_data; + + io_tw_lock(req->ctx, tw); + + if (!iof->futexv_unqueued) { + int res; + + res = futex_unqueue_multiple(ifd->futexv, iof->futex_nr); + if (res != -1) + io_req_set_res(req, res, 0); + } + + io_req_async_data_free(req); + __io_futex_complete(tw_req, tw); +} + +static bool io_futexv_claim(struct io_futexv_data *ifd) +{ + if (test_bit(0, &ifd->owned) || test_and_set_bit_lock(0, &ifd->owned)) + return false; + return true; +} + +static bool __io_futex_cancel(struct io_kiocb *req) +{ + /* futex wake already done or in progress */ + if (req->opcode == IORING_OP_FUTEX_WAIT) { + struct io_futex_data *ifd = req->async_data; + + if (!futex_unqueue(&ifd->q)) + return false; + req->io_task_work.func = io_futex_complete; + } else { + struct io_futexv_data *ifd = req->async_data; + + if (!io_futexv_claim(ifd)) + return false; + req->io_task_work.func = io_futexv_complete; + } + + hlist_del_init(&req->hash_node); + io_req_set_res(req, -ECANCELED, 0); + io_req_task_work_add(req); + return true; +} + +int io_futex_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd, + unsigned int issue_flags) +{ + return io_cancel_remove(ctx, cd, issue_flags, &ctx->futex_list, __io_futex_cancel); +} + +bool io_futex_remove_all(struct io_ring_ctx *ctx, struct io_uring_task *tctx, + bool cancel_all) +{ + return io_cancel_remove_all(ctx, tctx, &ctx->futex_list, cancel_all, __io_futex_cancel); +} + +int io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); + u32 flags; + + if (unlikely(sqe->len || sqe->futex_flags || sqe->buf_index || + sqe->file_index)) + return -EINVAL; + + iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr)); + iof->futex_val = READ_ONCE(sqe->addr2); + iof->futex_mask = READ_ONCE(sqe->addr3); + flags = READ_ONCE(sqe->fd); + + if (flags & ~FUTEX2_VALID_MASK) + return -EINVAL; + + iof->futex_flags = futex2_to_flags(flags); + if (!futex_flags_valid(iof->futex_flags)) + return -EINVAL; + + if (!futex_validate_input(iof->futex_flags, iof->futex_val) || + !futex_validate_input(iof->futex_flags, iof->futex_mask)) + return -EINVAL; + + return 0; +} + +int io_futex_wait_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); + int ret; + + ret = io_futex_prep(req, sqe); + if (unlikely(ret)) + return ret; + + /* inflight tracking only needed for mm private hash */ + if (!(iof->futex_flags & FLAGS_SHARED)) + io_req_track_inflight(req); + return 0; +} + +static void io_futex_wakev_fn(struct wake_q_head *wake_q, struct futex_q *q) +{ + struct io_kiocb *req = q->wake_data; + struct io_futexv_data *ifd = req->async_data; + + if (!io_futexv_claim(ifd)) { + __futex_wake_mark(q); + return; + } + if (unlikely(!__futex_wake_mark(q))) + return; + + io_req_set_res(req, 0, 0); + req->io_task_work.func = io_futexv_complete; + __io_req_task_work_add(req, IOU_F_TWQ_IN_WAKE); +} + +int io_futexv_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); + struct io_futexv_data *ifd; + unsigned int i; + int ret; + + /* No flags or mask supported for waitv */ + if (unlikely(sqe->fd || sqe->buf_index || sqe->file_index || + sqe->addr2 || sqe->futex_flags || sqe->addr3)) + return -EINVAL; + + iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr)); + iof->futex_nr = READ_ONCE(sqe->len); + if (!iof->futex_nr || iof->futex_nr > FUTEX_WAITV_MAX) + return -EINVAL; + + ifd = kzalloc_flex(struct io_futexv_data, futexv, iof->futex_nr, + GFP_KERNEL_ACCOUNT); + if (!ifd) + return -ENOMEM; + + ret = futex_parse_waitv(ifd->futexv, iof->uaddr, iof->futex_nr, + io_futex_wakev_fn, req); + if (ret) { + kfree(ifd); + return ret; + } + + /* inflight tracking only needed for mm private hash */ + for (i = 0; i < iof->futex_nr; i++) { + if (!(ifd->futexv[i].w.flags & FLAGS_SHARED)) { + io_req_track_inflight(req); + break; + } + } + + iof->futexv_unqueued = 0; + req->flags |= REQ_F_ASYNC_DATA; + req->async_data = ifd; + return 0; +} + +static void io_futex_wake_fn(struct wake_q_head *wake_q, struct futex_q *q) +{ + struct io_futex_data *ifd = container_of(q, struct io_futex_data, q); + struct io_kiocb *req = ifd->req; + + if (unlikely(!__futex_wake_mark(q))) + return; + + io_req_set_res(req, 0, 0); + req->io_task_work.func = io_futex_complete; + __io_req_task_work_add(req, IOU_F_TWQ_IN_WAKE); +} + +int io_futexv_wait(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); + struct io_futexv_data *ifd = req->async_data; + struct io_ring_ctx *ctx = req->ctx; + int ret, woken = -1; + + io_ring_submit_lock(ctx, issue_flags); + + ret = futex_wait_multiple_setup(ifd->futexv, iof->futex_nr, &woken); + + /* + * Error case, ret is < 0. Mark the request as failed. + */ + if (unlikely(ret < 0)) { + io_ring_submit_unlock(ctx, issue_flags); + req_set_fail(req); + io_req_set_res(req, ret, 0); + io_req_async_data_free(req); + return IOU_COMPLETE; + } + + /* + * 0 return means that we successfully setup the waiters, and that + * nobody triggered a wakeup while we were doing so. If the wakeup + * happened post setup, the task_work will be run post this issue and + * under the submission lock. 1 means We got woken while setting up, + * let that side do the completion. Note that + * futex_wait_multiple_setup() will have unqueued all the futexes in + * this case. Mark us as having done that already, since this is + * different from normal wakeup. + */ + if (!ret) { + /* + * If futex_wait_multiple_setup() returns 0 for a + * successful setup, then the task state will not be + * runnable. This is fine for the sync syscall, as + * it'll be blocking unless we already got one of the + * futexes woken, but it obviously won't work for an + * async invocation. Mark us runnable again. + */ + __set_current_state(TASK_RUNNING); + hlist_add_head(&req->hash_node, &ctx->futex_list); + } else { + iof->futexv_unqueued = 1; + if (woken != -1) + io_req_set_res(req, woken, 0); + } + + io_ring_submit_unlock(ctx, issue_flags); + return IOU_ISSUE_SKIP_COMPLETE; +} + +int io_futex_wait(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); + struct io_ring_ctx *ctx = req->ctx; + struct io_futex_data *ifd = NULL; + int ret; + + if (!iof->futex_mask) { + ret = -EINVAL; + goto done; + } + + io_ring_submit_lock(ctx, issue_flags); + ifd = io_cache_alloc(&ctx->futex_cache, GFP_NOWAIT); + if (!ifd) { + ret = -ENOMEM; + goto done_unlock; + } + + req->flags |= REQ_F_ASYNC_DATA; + req->async_data = ifd; + ifd->q = futex_q_init; + ifd->q.bitset = iof->futex_mask; + ifd->q.wake = io_futex_wake_fn; + ifd->req = req; + + ret = futex_wait_setup(iof->uaddr, iof->futex_val, iof->futex_flags, + &ifd->q, NULL, NULL); + if (!ret) { + hlist_add_head(&req->hash_node, &ctx->futex_list); + io_ring_submit_unlock(ctx, issue_flags); + + return IOU_ISSUE_SKIP_COMPLETE; + } + +done_unlock: + io_ring_submit_unlock(ctx, issue_flags); +done: + if (ret < 0) + req_set_fail(req); + io_req_set_res(req, ret, 0); + io_req_async_data_free(req); + return IOU_COMPLETE; +} + +int io_futex_wake(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex); + int ret; + + /* + * Strict flags - ensure that waking 0 futexes yields a 0 result. + * See commit 43adf8449510 ("futex: FLAGS_STRICT") for details. + */ + ret = futex_wake(iof->uaddr, FLAGS_STRICT | iof->futex_flags, NULL, + iof->futex_val, iof->futex_mask); + if (ret < 0) + req_set_fail(req); + io_req_set_res(req, ret, 0); + return IOU_COMPLETE; +} -- cgit v1.3.1