| Message ID | 20110302150422.GA13257@us.ibm.com |
|---|---|
| State | New |
| Headers | show |
On Wed, Mar 2, 2011 at 3:04 PM, Ryan Harper <ryanh@us.ibm.com> wrote: > If the block device has been closed, we no longer have a medium to submit > IO against, check for this before submitting io. This prevents a segfault > further in the code where we dereference elements of the block driver. > > Signed-off-by: Ryan Harper <ryanh@us.ibm.com> > --- > block.c | 5 +++++ > 1 files changed, 5 insertions(+), 0 deletions(-) > > diff --git a/block.c b/block.c > index 92dd3fe..534e1bc 100644 > --- a/block.c > +++ b/block.c > @@ -2407,6 +2407,11 @@ int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs, int num_reqs) > return 0; > } > > + /* don't submit writes if we don't have a medium */ > + if (bs->drv == NULL) { > + return -1; > + } > + Most other bdrv_*() calls will error out immediately if !bs->drv. Here you check only after returning success for num_reqs == 0. I don't think it makes a huge difference and can see how these semantics are handy (saves caller checking for num_reqs == 0), but I wanted to point it out. More importantly, we're not obeying the contract of this function here. reqs[].error must be set to -ENOMEDIUM before returning -1. Otherwise the caller thinks that reqs[] callbacks will still be invoked in the future and cannot complete those requests. Stefan
diff --git a/block.c b/block.c index 92dd3fe..534e1bc 100644 --- a/block.c +++ b/block.c @@ -2407,6 +2407,11 @@ int bdrv_aio_multiwrite(BlockDriverState *bs, BlockRequest *reqs, int num_reqs) return 0; } + /* don't submit writes if we don't have a medium */ + if (bs->drv == NULL) { + return -1; + } + // Create MultiwriteCB structure mcb = qemu_mallocz(sizeof(*mcb) + num_reqs * sizeof(*mcb->callbacks)); mcb->num_requests = 0;
If the block device has been closed, we no longer have a medium to submit IO against, check for this before submitting io. This prevents a segfault further in the code where we dereference elements of the block driver. Signed-off-by: Ryan Harper <ryanh@us.ibm.com> --- block.c | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-)