Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
io_uring/eventfd: clean up rcu locking
Conditional locking is never welcome if there are better options. Move
rcu locking into io_eventfd_signal(), make it unconditional and use
guards. It also helps with sparse warnings.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/91a925e708ca8a5aa7fee61f96d29b24ea9adeaf.1745493845.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
authored by
Pavel Begunkov
and committed by
Jens Axboe
da01f60f
62f666df
+7
-17
+7
-17
io_uring/eventfd.c
+7
-17
io_uring/eventfd.c
···
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io_eventfd_put(ev_fd);
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}
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-
static void io_eventfd_release(struct io_ev_fd *ev_fd, bool put_ref)
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-
{
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if (put_ref)
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io_eventfd_put(ev_fd);
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rcu_read_unlock();
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}
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-
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/*
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* Returns true if the caller should put the ev_fd reference, false if not.
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*/
···
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{
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struct io_ev_fd *ev_fd;
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if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED)
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return NULL;
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rcu_read_lock();
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-
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/*
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* rcu_dereference ctx->io_ev_fd once and use it for both for checking
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* and eventfd_signal
···
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if (io_eventfd_trigger(ev_fd) && refcount_inc_not_zero(&ev_fd->refs))
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return ev_fd;
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rcu_read_unlock();
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return NULL;
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}
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void io_eventfd_signal(struct io_ring_ctx *ctx, bool cqe_event)
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{
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bool skip = false, put_ref = true;
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bool skip = false;
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struct io_ev_fd *ev_fd;
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if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED)
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return;
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+
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guard(rcu)();
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ev_fd = io_eventfd_grab(ctx);
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if (!ev_fd)
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return;
···
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spin_unlock(&ctx->completion_lock);
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}
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if (!skip)
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put_ref = __io_eventfd_signal(ev_fd);
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io_eventfd_release(ev_fd, put_ref);
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if (skip || __io_eventfd_signal(ev_fd))
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io_eventfd_put(ev_fd);
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}
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int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg,