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fixup patch "ide: avoid potential deadlock when draining during trim"

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The patch was incomplete and (re-)introduced an issue with a potential
failing assertion upon cancelation of the DMA request.

There is a patch on qemu-devel now[0], and it's the same as this one
code-wise (except for comments). But the discussion is still ongoing.
While there shouldn't be a real issue with the patch, there might be
better approaches. The plan is to use this as a stop-gap for now and
pick up the proper solution once it's ready.

[0]: https://lists.nongnu.org/archive/html/qemu-devel/2023-03/msg03325.html

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
This commit is contained in:
Fiona Ebner 2023-03-09 14:37:34 +01:00 committed by Thomas Lamprecht
parent 67cae45f41
commit 3a94e1a186
1 changed files with 25 additions and 3 deletions
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28
debian/patches/extra/0011-ide-avoid-potential-deadlock-when-draining-during-tr.patch vendored
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@ -37,15 +37,25 @@ Thus, even after moving the blk_inc_in_flight to above the
replay_bh_schedule_event call, the invariant "ide_issue_trim_cb
returns with an accompanying in-flight count" is still satisfied.
However, the issue 7e5cdb345f fixed for canceling resurfaces, because
ide_cancel_dma_sync assumes that it just needs to drain once. But now
the in_flight count is not consistently > 0 during the trim operation.
So, change it to drain until !s->bus->dma->aiocb, which means that the
operation finished (s->bus->dma->aiocb is cleared by ide_set_inactive
via the ide_dma_cb when the end of the transfer is reached).
Discussion here:
https://lists.nongnu.org/archive/html/qemu-devel/2023-03/msg02506.html
Fixes: 7e5cdb345f ("ide: Increment BB in-flight counter for TRIM BH")
Suggested-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
---
hw/ide/core.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
hw/ide/core.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/hw/ide/core.c b/hw/ide/core.c
index 39afdc0006..6474522bc9 100644
index 39afdc0006..b67c1885a8 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -443,7 +443,7 @@ static void ide_trim_bh_cb(void *opaque)
@ -76,3 +86,15 @@ index 39afdc0006..6474522bc9 100644
iocb = blk_aio_get(&trim_aiocb_info, s->blk, cb, cb_opaque);
iocb->s = s;
iocb->bh = qemu_bh_new(ide_trim_bh_cb, iocb);
@@ -739,8 +738,9 @@ void ide_cancel_dma_sync(IDEState *s)
*/
if (s->bus->dma->aiocb) {
trace_ide_cancel_dma_sync_remaining();
- blk_drain(s->blk);
- assert(s->bus->dma->aiocb == NULL);
+ while (s->bus->dma->aiocb) {
+ blk_drain(s->blk);
+ }
}
}