gwj / at91sam9263 · Commits

Commit 986c28d655dc9196c9c426c667c1764bd3d6d5bd

Authored by Andrea Arcangeli
Committed by Christoph Hellwig
1 parent e19252d3

fix qemu_aio_flush 

qemu_aio_wait by invoking the bh or one of the aio completion
callbacks, could end up submitting new pending aio, breaking the
invariant that qemu_aio_flush returns only when no pending aio is
outstanding (possibly a problem for migration as such).

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Kevin Wolf <kwolf@redhat.com>
Inline Side-by-side
Showing 2 changed files with 10 additions and 5 deletions
... ... @@ -103,11 +103,15 @@ void qemu_aio_flush(void)
103 103 do {
104 104 ret = 0;
105 105  
  106 + /*
  107 + * If there are pending emulated aio start them now so flush
  108 + * will be able to return 1.
  109 + */
  110 + qemu_aio_wait();
  111 +
106 112 LIST_FOREACH(node, &aio_handlers, node) {
107 113 ret |= node->io_flush(node->opaque);
108 114 }
109   -
110   - qemu_aio_wait();
111 115 } while (ret > 0);
112 116 }
113 117  
... ...
qemu-aio.h
  View file @986c28d
... ... @@ -24,9 +24,10 @@ typedef int (AioFlushHandler)(void *opaque);
24 24 * outstanding AIO operations have been completed or cancelled. */
25 25 void qemu_aio_flush(void);
26 26  
27   -/* Wait for a single AIO completion to occur. This function will until a
28   - * single AIO opeartion has completed. It is intended to be used as a looping
29   - * primative when simulating synchronous IO based on asynchronous IO. */
  27 +/* Wait for a single AIO completion to occur. This function will wait
  28 + * until a single AIO event has completed and it will ensure something
  29 + * has moved before returning. This can issue new pending aio as
  30 + * result of executing I/O completion or bh callbacks. */
30 31 void qemu_aio_wait(void);
31 32  
32 33 /* Register a file descriptor and associated callbacks. Behaves very similarly
... ...