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[GIT PULL] man/io_uring_setup.2: fix memory ordering #949

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[GIT PULL] man/io_uring_setup.2: fix memory ordering #949

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8 changes: 4 additions & 4 deletions man/io_uring_setup.2
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Original file line number Diff line number Diff line change
Expand Up @@ -109,11 +109,11 @@ call with the following code sequence:
.EX
/*
* Ensure that the wakeup flag is read after the tail pointer
* has been written. It's important to use memory load acquire
* semantics for the flags read, as otherwise the application
* and the kernel might not agree on the consistency of the
* wakeup flag.
* has been written. A full memory barrier is required because
* this is a read-after-write (which cannot be synchronized
* using acquire/release memory ordering).
*/
smp_mb();
unsigned flags = atomic_load_relaxed(sq_ring->flags);
if (flags & IORING_SQ_NEED_WAKEUP)
io_uring_enter(fd, 0, 0, IORING_ENTER_SQ_WAKEUP);
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