summaryrefslogtreecommitdiff
path: root/io_uring/poll.c
AgeCommit message (Collapse)AuthorFilesLines
2023-01-12io_uring/poll: attempt request issue after racy poll wakeupJens Axboe1-11/+20
If we have multiple requests waiting on the same target poll waitqueue, then it's quite possible to get a request triggered and get disappointed in not being able to make any progress with it. If we race in doing so, we'll potentially leave the poll request on the internal tables, but removed from the waitqueue. That means that any subsequent trigger of the poll waitqueue will not kick that request into action, causing an application to potentially wait for completion of a request that will never happen. Fix this by adding a new poll return state, IOU_POLL_REISSUE. Rather than have complicated logic for how to re-arm a given type of request, just punt it for a reissue. While in there, move the 'ret' variable to the only section where it gets used. This avoids confusion the scope of it. Cc: stable@vger.kernel.org Fixes: eb0089d629ba ("io_uring: single shot poll removal optimisation") Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-01-10io_uring/poll: add hash if ready poll request can't complete inlineJens Axboe1-5/+12
If we don't, then we may lose access to it completely, leading to a request leak. This will eventually stall the ring exit process as well. Cc: stable@vger.kernel.org Fixes: 49f1c68e048f ("io_uring: optimise submission side poll_refs") Reported-and-tested-by: syzbot+6c95df01470a47fc3af4@syzkaller.appspotmail.com Link: https://lore.kernel.org/io-uring/0000000000009f829805f1ce87b2@google.com/ Suggested-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-30io_uring: combine poll tw handlersPavel Begunkov1-33/+21
Merge apoll and regular poll tw handlers, it will help with inlining. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/482e59edb9fc81bd275fdbf486837330fb27120a.1669821213.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-30io_uring: improve poll warning handlingPavel Begunkov1-1/+1
Don't try to complete requests if their refs are broken and we've got a warning, it's much better to drop them and potentially leaking than double freeing. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/31edf9f96f05d03ab62c114508a231a2dce434cb.1669821213.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-30io_uring: remove ctx variable in io_poll_check_eventsPavel Begunkov1-2/+1
ctx is only used by io_poll_check_events() for multishot poll CQE posting, don't save it on stack in advance. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/552c1771f8a0e7688afdb4f538ead245f53e80e7.1669821213.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-30io_uring: carve io_poll_check_events fast pathPavel Begunkov1-19/+22
The fast path in io_poll_check_events() is when we have only one (i.e. master) reference. Move all verification, cancellations checks, edge case handling and so on under a common if. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/8c21c5d5e027e32dc553705e88796dec79ff6f93.1669821213.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-29Merge branch 'for-6.2/io_uring' into for-6.2/io_uring-nextJens Axboe1-14/+19
* for-6.2/io_uring: (41 commits) io_uring: keep unlock_post inlined in hot path io_uring: don't use complete_post in kbuf io_uring: spelling fix io_uring: remove io_req_complete_post_tw io_uring: allow multishot polled reqs to defer completion io_uring: remove overflow param from io_post_aux_cqe io_uring: add lockdep assertion in io_fill_cqe_aux io_uring: make io_fill_cqe_aux static io_uring: add io_aux_cqe which allows deferred completion io_uring: allow defer completion for aux posted cqes io_uring: defer all io_req_complete_failed io_uring: always lock in io_apoll_task_func io_uring: remove iopoll spinlock io_uring: iopoll protect complete_post io_uring: inline __io_req_complete_put() io_uring: remove io_req_tw_post_queue io_uring: use io_req_task_complete() in timeout io_uring: hold locks for io_req_complete_failed io_uring: add completion locking for iopoll io_uring: kill io_cqring_ev_posted() and __io_cq_unlock_post() ...
2022-11-25io_uring/poll: fix poll_refs race with cancelationLin Ma1-1/+2
There is an interesting race condition of poll_refs which could result in a NULL pointer dereference. The crash trace is like: KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 0 PID: 30781 Comm: syz-executor.2 Not tainted 6.0.0-g493ffd6605b2 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 RIP: 0010:io_poll_remove_entry io_uring/poll.c:154 [inline] RIP: 0010:io_poll_remove_entries+0x171/0x5b4 io_uring/poll.c:190 Code: ... RSP: 0018:ffff88810dfefba0 EFLAGS: 00010202 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000040000 RDX: ffffc900030c4000 RSI: 000000000003ffff RDI: 0000000000040000 RBP: 0000000000000008 R08: ffffffff9764d3dd R09: fffffbfff3836781 R10: fffffbfff3836781 R11: 0000000000000000 R12: 1ffff11003422d60 R13: ffff88801a116b04 R14: ffff88801a116ac0 R15: dffffc0000000000 FS: 00007f9c07497700(0000) GS:ffff88811a600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffb5c00ea98 CR3: 0000000105680005 CR4: 0000000000770ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> io_apoll_task_func+0x3f/0xa0 io_uring/poll.c:299 handle_tw_list io_uring/io_uring.c:1037 [inline] tctx_task_work+0x37e/0x4f0 io_uring/io_uring.c:1090 task_work_run+0x13a/0x1b0 kernel/task_work.c:177 get_signal+0x2402/0x25a0 kernel/signal.c:2635 arch_do_signal_or_restart+0x3b/0x660 arch/x86/kernel/signal.c:869 exit_to_user_mode_loop kernel/entry/common.c:166 [inline] exit_to_user_mode_prepare+0xc2/0x160 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline] syscall_exit_to_user_mode+0x58/0x160 kernel/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x63/0xcd The root cause for this is a tiny overlooking in io_poll_check_events() when cocurrently run with poll cancel routine io_poll_cancel_req(). The interleaving to trigger use-after-free: CPU0 | CPU1 | io_apoll_task_func() | io_poll_cancel_req() io_poll_check_events() | // do while first loop | v = atomic_read(...) | // v = poll_refs = 1 | ... | io_poll_mark_cancelled() | atomic_or() | // poll_refs = IO_POLL_CANCEL_FLAG | 1 | atomic_sub_return(...) | // poll_refs = IO_POLL_CANCEL_FLAG | // loop continue | | | io_poll_execute() | io_poll_get_ownership() | // poll_refs = IO_POLL_CANCEL_FLAG | 1 | // gets the ownership v = atomic_read(...) | // poll_refs not change | | if (v & IO_POLL_CANCEL_FLAG) | return -ECANCELED; | // io_poll_check_events return | // will go into | // io_req_complete_failed() free req | | | io_apoll_task_func() | // also go into io_req_complete_failed() And the interleaving to trigger the kernel WARNING: CPU0 | CPU1 | io_apoll_task_func() | io_poll_cancel_req() io_poll_check_events() | // do while first loop | v = atomic_read(...) | // v = poll_refs = 1 | ... | io_poll_mark_cancelled() | atomic_or() | // poll_refs = IO_POLL_CANCEL_FLAG | 1 | atomic_sub_return(...) | // poll_refs = IO_POLL_CANCEL_FLAG | // loop continue | | v = atomic_read(...) | // v = IO_POLL_CANCEL_FLAG | | io_poll_execute() | io_poll_get_ownership() | // poll_refs = IO_POLL_CANCEL_FLAG | 1 | // gets the ownership | WARN_ON_ONCE(!(v & IO_POLL_REF_MASK))) | // v & IO_POLL_REF_MASK = 0 WARN | | | io_apoll_task_func() | // also go into io_req_complete_failed() By looking up the source code and communicating with Pavel, the implementation of this atomic poll refs should continue the loop of io_poll_check_events() just to avoid somewhere else to grab the ownership. Therefore, this patch simply adds another AND operation to make sure the loop will stop if it finds the poll_refs is exactly equal to IO_POLL_CANCEL_FLAG. Since io_poll_cancel_req() grabs ownership and will finally make its way to io_req_complete_failed(), the req will be reclaimed as expected. Fixes: aa43477b0402 ("io_uring: poll rework") Signed-off-by: Lin Ma <linma@zju.edu.cn> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> [axboe: tweak description and code style] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25io_uring: make poll refs more robustPavel Begunkov1-1/+35
poll_refs carry two functions, the first is ownership over the request. The second is notifying the io_poll_check_events() that there was an event but wake up couldn't grab the ownership, so io_poll_check_events() should retry. We want to make poll_refs more robust against overflows. Instead of always incrementing it, which covers two purposes with one atomic, check if poll_refs is elevated enough and if so set a retry flag without attempts to grab ownership. The gap between the bias check and following atomics may seem racy, but we don't need it to be strict. Moreover there might only be maximum 4 parallel updates: by the first and the second poll entries, __io_arm_poll_handler() and cancellation. From those four, only poll wake ups may be executed multiple times, but they're protected by a spin. Cc: stable@vger.kernel.org Reported-by: Lin Ma <linma@zju.edu.cn> Fixes: aa43477b04025 ("io_uring: poll rework") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/c762bc31f8683b3270f3587691348a7119ef9c9d.1668963050.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25io_uring: cmpxchg for poll arm refs releasePavel Begunkov1-5/+3
Replace atomically substracting the ownership reference at the end of arming a poll with a cmpxchg. We try to release ownership by setting 0 assuming that poll_refs didn't change while we were arming. If it did change, we keep the ownership and use it to queue a tw, which is fully capable to process all events and (even tolerates spurious wake ups). It's a bit more elegant as we reduce races b/w setting the cancellation flag and getting refs with this release, and with that we don't have to worry about any kinds of underflows. It's not the fastest path for polling. The performance difference b/w cmpxchg and atomic dec is usually negligible and it's not the fastest path. Cc: stable@vger.kernel.org Fixes: aa43477b04025 ("io_uring: poll rework") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/0c95251624397ea6def568ff040cad2d7926fd51.1668963050.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25io_uring: add io_aux_cqe which allows deferred completionDylan Yudaken1-2/+2
Use the just introduced deferred post cqe completion state when possible in io_aux_cqe. If not possible fallback to io_post_aux_cqe. This introduces a complication because of allow_overflow. For deferred completions we cannot know without locking the completion_lock if it will overflow (and even if we locked it, another post could sneak in and cause this cqe to be in overflow). However since overflow protection is mostly a best effort defence in depth to prevent infinite loops of CQEs for poll, just checking the overflow bit is going to be good enough and will result in at most 16 (array size of deferred cqes) overflows. Suggested-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Dylan Yudaken <dylany@meta.com> Link: https://lore.kernel.org/r/20221124093559.3780686-6-dylany@meta.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25io_uring: defer all io_req_complete_failedDylan Yudaken1-1/+1
All failures happen under lock now, and can be deferred. To be consistent when the failure has happened after some multishot cqe has been deferred (and keep ordering), always defer failures. To make this obvious at the caller (and to help prevent a future bug) rename io_req_complete_failed to io_req_defer_failed. Signed-off-by: Dylan Yudaken <dylany@meta.com> Link: https://lore.kernel.org/r/20221124093559.3780686-4-dylany@meta.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-25io_uring: always lock in io_apoll_task_funcDylan Yudaken1-1/+2
This is required for the failure case (io_req_complete_failed) and is missing. The alternative would be to only lock in the failure path, however all of the non-error paths in io_poll_check_events that do not do not return IOU_POLL_NO_ACTION end up locking anyway. The only extraneous lock would be for the multishot poll overflowing the CQE ring, however multishot poll would probably benefit from being locked as it will allow completions to be batched. So it seems reasonable to lock always. Signed-off-by: Dylan Yudaken <dylany@meta.com> Link: https://lore.kernel.org/r/20221124093559.3780686-3-dylany@meta.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-23io_uring: iopoll protect complete_postPavel Begunkov1-1/+1
io_req_complete_post() may be used by iopoll enabled rings, grab locks in this case. That requires to pass issue_flags to propagate the locking state. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/cc6d854065c57c838ca8e8806f707a226b70fd2d.1669203009.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-22Revert "io_uring: disallow self-propelled ring polling"Jens Axboe1-2/+0
This reverts commit 7fdbc5f014c3f71bc44673a2d6c5bb2d12d45f25. This patch dealt with a subset of the real problem, which is a potential circular dependency on the wakup path for io_uring itself. Outside of io_uring, eventfd can also trigger this (see details in 03e02acda8e2) and so can epoll (see details in caf1aeaffc3b). Now that we have a generic solution to this problem, get rid of the io_uring specific work-around. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-22io_uring: pass in EPOLL_URING_WAKE for eventfd signaling and wakeupsJens Axboe1-0/+8
Pass in EPOLL_URING_WAKE when signaling eventfd or doing poll related wakups, so that we can check for a circular event dependency between eventfd and epoll. If this flag is set when our wakeup handlers are called, then we know we have a dependency that needs to terminate multishot requests. eventfd and epoll are the only such possible dependencies. Cc: stable@vger.kernel.org # 6.0 Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-21io_uring/poll: remove outdated comments of cachingLin Ma1-6/+1
Previous commit 13a99017ff19 ("io_uring: remove events caching atavisms") entirely removes the events caching optimization introduced by commit 81459350d581 ("io_uring: cache req->apoll->events in req->cflags"). Hence the related comment should also be removed to avoid misunderstanding. Fixes: 13a99017ff19 ("io_uring: remove events caching atavisms") Signed-off-by: Lin Ma <linma@zju.edu.cn> Link: https://lore.kernel.org/r/20221110060313.16303-1-linma@zju.edu.cn Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-21io_uring: fix two assignments in if conditionsXinghui Li1-2/+5
Fixes two errors: "ERROR: do not use assignment in if condition 130: FILE: io_uring/net.c:130: + if (!(issue_flags & IO_URING_F_UNLOCKED) && ERROR: do not use assignment in if condition 599: FILE: io_uring/poll.c:599: + } else if (!(issue_flags & IO_URING_F_UNLOCKED) &&" reported by checkpatch.pl in net.c and poll.c . Signed-off-by: Xinghui Li <korantli@tencent.com> Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/r/20221102082503.32236-1-korantwork@gmail.com [axboe: style tweaks] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-18io_uring: disallow self-propelled ring pollingPavel Begunkov1-0/+2
When we post a CQE we wake all ring pollers as it normally should be. However, if a CQE was generated by a multishot poll request targeting its own ring, it'll wake that request up, which will make it to post a new CQE, which will wake the request and so on until it exhausts all CQ entries. Don't allow multishot polling io_uring files but downgrade them to oneshots, which was always stated as a correct behaviour that the userspace should check for. Cc: stable@vger.kernel.org Fixes: aa43477b04025 ("io_uring: poll rework") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/3124038c0e7474d427538c2d915335ec28c92d21.1668785722.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-17io_uring: fix tw losing poll eventsPavel Begunkov1-0/+7
We may never try to process a poll wake and its mask if there was multiple wake ups racing for queueing up a tw. Force io_poll_check_events() to update the mask by vfs_poll(). Cc: stable@vger.kernel.org Fixes: aa43477b04025 ("io_uring: poll rework") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/00344d60f8b18907171178d7cf598de71d127b0b.1668710222.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-17io_uring: update res mask in io_poll_check_eventsPavel Begunkov1-0/+3
When io_poll_check_events() collides with someone attempting to queue a task work, it'll spin for one more time. However, it'll continue to use the mask from the first iteration instead of updating it. For example, if the first wake up was a EPOLLIN and the second EPOLLOUT, the userspace will not get EPOLLOUT in time. Clear the mask for all subsequent iterations to force vfs_poll(). Cc: stable@vger.kernel.org Fixes: aa43477b04025 ("io_uring: poll rework") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/2dac97e8f691231049cb259c4ae57e79e40b537c.1668710222.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-11io_uring/poll: lockdep annote io_poll_req_insert_lockedPavel Begunkov1-0/+2
Add a lockdep annotation in io_poll_req_insert_locked(). Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/8115d8e702733754d0aea119e9b5bb63d1eb8b24.1668184658.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-11-11io_uring/poll: fix double poll req->flags racesPavel Begunkov1-12/+17
io_poll_double_prepare() | io_poll_wake() | poll->head = NULL smp_load(&poll->head); /* NULL */ | flags = req->flags; | | req->flags &= ~SINGLE_POLL; req->flags = flags | DOUBLE_POLL | The idea behind io_poll_double_prepare() is to serialise with the first poll entry by taking the wq lock. However, it's not safe to assume that io_poll_wake() is not running when we can't grab the lock and so we may race modifying req->flags. Skip double poll setup if that happens. It's ok because the first poll entry will only be removed when it's definitely completing, e.g. pollfree or oneshot with a valid mask. Fixes: 49f1c68e048f1 ("io_uring: optimise submission side poll_refs") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/b7fab2d502f6121a7d7b199fe4d914a43ca9cdfd.1668184658.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-29io_uring/poll: disable level triggered pollJens Axboe1-1/+1
Stefan reports that there are issues with the level triggered notification. Since we're late in the cycle, and it was introduced for the 6.0 release, just disable it at prep time and we can bring this back when Samba is happy with it. Reported-by: Stefan Metzmacher <metze@samba.org> Reviewed-by: Stefan Metzmacher <metze@samba.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-08-13io_uring: make io_kiocb_to_cmd() typesafeStefan Metzmacher1-8/+8
We need to make sure (at build time) that struct io_cmd_data is not casted to a structure that's larger. Signed-off-by: Stefan Metzmacher <metze@samba.org> Link: https://lore.kernel.org/r/c024cdf25ae19fc0319d4180e2298bade8ed17b8.1660201408.git.metze@samba.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: add abstraction around apoll cacheJens Axboe1-13/+5
In preparation for adding limits, and one more user, abstract out the core bits of the allocation+free cache. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: move apoll cache to poll.cJens Axboe1-0/+12
This is where it's used, move the flush handler in there. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: consolidate hash_locked io-wq handlingPavel Begunkov1-5/+7
Don't duplicate code disabling REQ_F_HASH_LOCKED for IO_URING_F_UNLOCKED (i.e. io-wq), move the handling into __io_arm_poll_handler(). Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/0ff0ffdfaa65b3d536131535c3dad3c63d9b7bb0.1657203020.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: clear REQ_F_HASH_LOCKED on hash removalPavel Begunkov1-5/+2
Instead of clearing REQ_F_HASH_LOCKED while arming a poll, unset the bit when we're removing the entry from the table in io_poll_tw_hash_eject(). Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/02e48bb88d6f1480c94ac2924c43ad1fbd48e92a.1657203020.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: don't race double poll setting REQ_F_ASYNC_DATAPavel Begunkov1-3/+3
Just as with io_poll_double_prepare() setting REQ_F_DOUBLE_POLL, we can race with the first poll entry when setting REQ_F_ASYNC_DATA. Move it under io_poll_double_prepare(). Fixes: a18427bb2d9b ("io_uring: optimise submission side poll_refs") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/df6920f509c11115aa2bce8b34dc5fdb0eb98920.1657203020.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: don't miss setting REQ_F_DOUBLE_POLLPavel Begunkov1-8/+10
When adding a second poll entry we should set REQ_F_DOUBLE_POLL unconditionally. We might race with the first entry removal but that doesn't change the rule. Fixes: a18427bb2d9b ("io_uring: optimise submission side poll_refs") Reported-and-tested-by: syzbot+49950ba66096b1f0209b@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/8b680d83ded07424db83e8745585e7a6d72826ef.1657203020.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: fix multishot poll on overflowDylan Yudaken1-2/+4
On overflow, multishot poll can still complete with the IORING_CQE_F_MORE flag set. If in the meantime the user clears a CQE and a the poll was cancelled then the poll will post a CQE without the IORING_CQE_F_MORE (and likely result -ECANCELED). However when processing the application will encounter the non-overflow CQE which indicates that there will be no more events posted. Typical userspace applications would free memory associated with the poll in this case. It will then subsequently receive the earlier CQE which has overflowed, which breaks the contract given by the IORING_CQE_F_MORE flag. Signed-off-by: Dylan Yudaken <dylany@fb.com> Link: https://lore.kernel.org/r/20220630091231.1456789-9-dylany@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: add allow_overflow to io_post_aux_cqeDylan Yudaken1-1/+1
Some use cases of io_post_aux_cqe would not want to overflow as is, but might want to change the flags/result. For example multishot receive requires in order CQE, and so if there is an overflow it would need to stop receiving until the overflow is taken care of. Signed-off-by: Dylan Yudaken <dylany@fb.com> Link: https://lore.kernel.org/r/20220630091231.1456789-8-dylany@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: add IOU_STOP_MULTISHOT return codeDylan Yudaken1-2/+9
For multishot we want a way to signal the caller that multishot has ended but also this might not be an error return. For example sockets return 0 when closed, which should end a multishot recv, but still have a CQE with result 0 Introduce IOU_STOP_MULTISHOT which does this and indicates that the return code is stored inside req->cqe Signed-off-by: Dylan Yudaken <dylany@fb.com> Link: https://lore.kernel.org/r/20220630091231.1456789-7-dylany@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: clean up io_poll_check_events return valuesDylan Yudaken1-11/+16
The values returned are a bit confusing, where 0 and 1 have implied meaning, so add some definitions for them. Signed-off-by: Dylan Yudaken <dylany@fb.com> Link: https://lore.kernel.org/r/20220630091231.1456789-6-dylany@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: move POLLFREE handling to separate functionJens Axboe1-23/+27
We really don't care about this at all in terms of performance. Outside of having it already be marked unlikely(), shove it into a separate __cold function. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: optimise submission side poll_refsPavel Begunkov1-21/+67
The final poll_refs put in __io_arm_poll_handler() takes quite some cycles. When we're arming from the original task context task_work won't be run, so in this case we can assume that we won't race with task_works and so not take the initial ownership ref. One caveat is that after arming a poll we may race with it, so we have to add a bunch of io_poll_get_ownership() hidden inside of io_poll_can_finish_inline() whenever we want to complete arming inline. For the same reason we can't just set REQ_F_DOUBLE_POLL in __io_queue_proc() and so need to sync with the first poll entry by taking its wq head lock. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/8825315d7f5e182ac1578a031e546f79b1c97d01.1655990418.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: refactor poll arm error handlingPavel Begunkov1-23/+21
__io_arm_poll_handler() errors parsing is a horror, in case it failed it returns 0 and the caller is expected to look at ipt.error, which already led us to a number of problems before. When it returns a valid mask, leave it as it's not, i.e. return 1 and store the mask in ipt.result_mask. In case of a failure that can be handled inline return an error code (negative value), and return 0 if __io_arm_poll_handler() took ownership of the request and will complete it. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/018cacdaef5fe95d7dc56b32e85d752cab7607f6.1655990418.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: change arm poll return valuesPavel Begunkov1-2/+5
The rules for __io_arm_poll_handler()'s result parsing are complicated, as the first step don't pass return a mask but pass back a positive return code and fill ipt->result_mask. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/529e29e9f97f2e6e383ccd44234d8b576a83a921.1655990418.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: add a helper for apoll allocPavel Begunkov1-16/+28
Extract a helper function for apoll allocation, makes the code easier to read. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/2f93282b47dd678e805dd0d7097f66968ced495c.1655990418.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: remove events caching atavismsPavel Begunkov1-10/+8
Remove events argument from *io_poll_execute(), it's not needed and not used. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/12efd4e15c6a90cf9e5b59807cfcb57852b51dc7.1655990418.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: clean poll ->private flaggingPavel Begunkov1-3/+17
We store a req pointer in wqe->private but also take one bit to mark double poll entries. Replace macro helpers with inline functions for better type checking and also name the double flag. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/9a61240555c64ac0b7a9b0eb59a9efeb638a35a4.1655990418.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: add a warn_once for poll_findPavel Begunkov1-0/+5
io_poll_remove() expects poll_find() to search only for poll requests and passes a flag for this. Just be a little bit extra cautious considering lots of recent poll/cancellation changes and add a WARN_ON_ONCE checking that we don't get an apoll'ed request. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/ec9a66f1e22f99dcd02288d4e42f3cc6bb357804.1655684496.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: fix io_poll_remove_all clang warningsPavel Begunkov1-2/+5
clang complains on bitwise operations with bools, add a bit more verbosity to better show that we want to call io_poll_remove_all_table() twice but with different arguments. Reported-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/f11d21dcdf9233e0eeb15fa13b858a05a78eb310.1655684496.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: clean up tracing eventsPavel Begunkov1-3/+2
We have lots of trace events accepting an io_uring request and wanting to print some of its fields like user_data, opcode, flags and so on. However, as trace points were unaware of io_uring structures, we had to pass all the fields as arguments. Teach trace/events/io_uring.h about struct io_kiocb and stop the misery of passing a horde of arguments to trace helpers. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/40ff72f92798114e56d400f2b003beb6cde6ef53.1655384063.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: kill extra io_uring_types.h includesPavel Begunkov1-1/+0
io_uring/io_uring.h already includes io_uring_types.h, no need to include it every time. Kill it in a bunch of places, it prepares us for following patches. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/94d8c943fbe0ef949981c508ddcee7fc1c18850f.1655384063.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: don't expose io_fill_cqe_aux()Pavel Begunkov1-16/+8
Deduplicate some code and add a helper for filling an aux CQE, locking and notification. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/b7c6557c8f9dc5c4cfb01292116c682a0ff61081.1655455613.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: mutex locked poll hashingPavel Begunkov1-21/+96
Currently we do two extra spin lock/unlock pairs to add a poll/apoll request to the cancellation hash table and remove it from there. On the submission side we often already hold ->uring_lock and tw completion is likely to hold it as well. Add a second cancellation hash table protected by ->uring_lock. In concerns for latency because of a need to have the mutex locked on the completion side, use the new table only in following cases: 1) IORING_SETUP_SINGLE_ISSUER: only one task grabs uring_lock, so there is little to no contention and so the main tw hander will almost always end up grabbing it before calling callbacks. 2) IORING_SETUP_SQPOLL: same as with single issuer, only one task is a major user of ->uring_lock. 3) apoll: we normally grab the lock on the completion side anyway to execute the request, so it's free. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/1bbad9c78c454b7b92f100bbf46730a37df7194f.1655371007.git.asml.silence@gmail.com Reviewed-by: Hao Xu <howeyxu@tencent.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: propagate locking state to poll cancelPavel Begunkov1-1/+2
Poll cancellation will be soon need to grab ->uring_lock inside, pass the locking state, i.e. issue_flags, inside the cancellation functions. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/b86781d047727c07163443b57551a3fa57c7c5e1.1655371007.git.asml.silence@gmail.com Reviewed-by: Hao Xu <howeyxu@tencent.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-25io_uring: introduce a struct for hash tablePavel Begunkov1-18/+22
Instead of passing around a pointer to hash buckets, add a bit of type safety and wrap it into a structure. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/d65bc3faba537ec2aca9eabf334394936d44bd28.1655371007.git.asml.silence@gmail.com Reviewed-by: Hao Xu <howeyxu@tencent.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
generated by cgit v1.2.3 (git 2.39.0) at 2024-11-28 20:09:22 +0300