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9pfs: only free completed request if not flushed

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If a PDU has a flush request pending, the current code calls pdu_free()
twice:

1) pdu_complete()->pdu_free() with pdu->cancelled set, which does nothing

2) v9fs_flush()->pdu_free() with pdu->cancelled cleared, which moves the
   PDU back to the free list.

This works but it complexifies the logic of pdu_free().

With this patch, pdu_complete() only calls pdu_free() if no flush request
is pending, i.e. qemu_co_queue_next() returns false.

Since pdu_free() is now supposed to be called with pdu->cancelled cleared,
the check in pdu_free() is dropped and replaced by an assertion.

Signed-off-by: Greg Kurz <groug@kaod.org>
This commit is contained in:
Greg Kurz 2016-10-17 14:13:58 +02:00
parent 6868a420c5
commit f74e27bf0f
1 changed files with 7 additions and 11 deletions
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18
hw/9pfs/9p.c
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@ -627,14 +627,10 @@ V9fsPDU *pdu_alloc(V9fsState *s)
void pdu_free(V9fsPDU *pdu)
{
V9fsState *s = pdu->s;
/*
* Cancelled pdu are added back to the freelist
* by flush request .
*/
if (!pdu->cancelled) {
QLIST_REMOVE(pdu, next);
QLIST_INSERT_HEAD(&s->free_list, pdu, next);
}
g_assert(!pdu->cancelled);
QLIST_REMOVE(pdu, next);
QLIST_INSERT_HEAD(&s->free_list, pdu, next);
}
/*
@ -679,9 +675,9 @@ static void coroutine_fn pdu_complete(V9fsPDU *pdu, ssize_t len)
pdu_push_and_notify(pdu);
/* Now wakeup anybody waiting in flush for this request */
qemu_co_queue_next(&pdu->complete);
pdu_free(pdu);
if (!qemu_co_queue_next(&pdu->complete)) {
pdu_free(pdu);
}
}
static mode_t v9mode_to_mode(uint32_t mode, V9fsString *extension)