From c86422c5549c0983b4b4525b8f56a1c69dd67aa1 Mon Sep 17 00:00:00 2001 From: Emanuele Giuseppe Esposito Date: Fri, 13 Jan 2023 21:42:04 +0100 Subject: block: Convert bdrv_refresh_total_sectors() to co_wrapper_mixed BlockDriver->bdrv_getlength is categorized as IO callback, and it currently doesn't run in a coroutine. We should let it take a graph rdlock since the callback traverses the block nodes graph, which however is only possible in a coroutine. Therefore turn it into a co_wrapper to move the actual function into a coroutine where the lock can be taken. Because now this function creates a new coroutine and polls, we need to take the AioContext lock where it is missing, for the only reason that internally co_wrapper calls AIO_WAIT_WHILE and it expects to release the AioContext lock. This is especially messy when a co_wrapper creates a coroutine and polls in bdrv_open_driver, because this function has so many callers in so many context that it can easily lead to deadlocks. Therefore the new rule for bdrv_open_driver is that the caller must always hold the AioContext lock of the given bs (except if it is a coroutine), because the function calls bdrv_refresh_total_sectors() which is now a co_wrapper. Once the rwlock is ultimated and placed in every place it needs to be, we will poll using AIO_WAIT_WHILE_UNLOCKED and remove the AioContext lock. Signed-off-by: Emanuele Giuseppe Esposito Signed-off-by: Kevin Wolf Message-Id: <20230113204212.359076-7-kwolf@redhat.com> Reviewed-by: Emanuele Giuseppe Esposito Signed-off-by: Kevin Wolf --- hw/scsi/scsi-disk.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'hw') diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c index e493c28814..d4e360850f 100644 --- a/hw/scsi/scsi-disk.c +++ b/hw/scsi/scsi-disk.c @@ -2332,10 +2332,15 @@ static void scsi_disk_reset(DeviceState *dev) { SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev.qdev, dev); uint64_t nb_sectors; + AioContext *ctx; scsi_device_purge_requests(&s->qdev, SENSE_CODE(RESET)); + ctx = blk_get_aio_context(s->qdev.conf.blk); + aio_context_acquire(ctx); blk_get_geometry(s->qdev.conf.blk, &nb_sectors); + aio_context_release(ctx); + nb_sectors /= s->qdev.blocksize / BDRV_SECTOR_SIZE; if (nb_sectors) { nb_sectors--; -- cgit v1.2.3