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block/io_uring: revert "Use io_uring_register_ring_fd() to skip fd operations"

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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1193

The commit "Use io_uring_register_ring_fd() to skip fd operations" broke
when booting a guest with iothread and io_uring. That is because the
io_uring_register_ring_fd() call is made from the main thread instead of
IOThread where io_uring_submit() is called. It can not be guaranteed
to register the ring fd in the correct thread or unregister the same ring
fd if the IOThread is disabled. This optimization is not critical so we
will revert previous commit.

This reverts commit e2848bc574
and 77e3f038af.

Cc: qemu-stable@nongnu.org
Signed-off-by: Sam Li <faithilikerun@gmail.com>
Message-Id: <20220924144815.5591-1-faithilikerun@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Tested-by: Dario Faggioli <dfaggioli@suse.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Sam Li 2022-09-24 22:48:15 +08:00 committed by Kevin Wolf
parent 1e85c7259b
commit 7845e73147
2 changed files with 1 additions and 13 deletions
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13
block/io_uring.c
View file

@ -11,7 +11,6 @@
#include "qemu/osdep.h"
#include <liburing.h>
#include "block/aio.h"
#include "qemu/error-report.h"
#include "qemu/queue.h"
#include "block/block.h"
#include "block/raw-aio.h"
@ -19,7 +18,6 @@
#include "qapi/error.h"
#include "trace.h"
/* io_uring ring size */
#define MAX_ENTRIES 128
@ -432,17 +430,8 @@ LuringState *luring_init(Error **errp)
}
ioq_init(&s->io_q);
#ifdef CONFIG_LIBURING_REGISTER_RING_FD
if (io_uring_register_ring_fd(&s->ring) < 0) {
/*
* Only warn about this error: we will fallback to the non-optimized
* io_uring operations.
*/
warn_report("failed to register linux io_uring ring file descriptor");
}
#endif
return s;
}
void luring_cleanup(LuringState *s)

1
meson.build
View file

@ -1839,7 +1839,6 @@ config_host_data.set('CONFIG_LIBNFS', libnfs.found())
config_host_data.set('CONFIG_LIBSSH', libssh.found())
config_host_data.set('CONFIG_LINUX_AIO', libaio.found())
config_host_data.set('CONFIG_LINUX_IO_URING', linux_io_uring.found())
config_host_data.set('CONFIG_LIBURING_REGISTER_RING_FD', cc.has_function('io_uring_register_ring_fd', prefix: '#include <liburing.h>', dependencies:linux_io_uring))
config_host_data.set('CONFIG_LIBPMEM', libpmem.found())
config_host_data.set('CONFIG_NUMA', numa.found())
config_host_data.set('CONFIG_OPENGL', opengl.found())