Re: [Libguestfs] libnbd: When are callbacks freed

On Thu, Jul 13, 2023 at 09:53:58AM +0000, Tage Johansson wrote: > Apologize if resending, but I'm not sure my previous email was > actually delivered. > > > On 7/12/2023 10:33 PM, Eric Blake wrote: > > > >On Wed, Jul 12, 2023 at 03:19:59PM +0000, Tage Johansson wrote: > >>Hello, > >> > >> > >>While writing some tests for the Rust bindings, I discovered a > >>memory leak > >>with Valgrind due to a completion callback not being freed. More > >>specificly, > >>the completion callback of `aio_opt_info()` doesn't seem to be if > >>`aio_opt_info()` failes. In this case, `aio_opt_info()` was called in the > >>connected state, so it should indeed fail, but it should perhaps > >>also call > >>the free function associated with the callback. > >Can you paste the valgrind output showing the leak? > > > The Valgrind output is very Rust specific and only shows the Rust > allocations which goes into the completion callback and are lost. > > > But if you apply the following patch (which modifies > tests/opt-info.c) you shall see that the completion callback is not > called.

> > I have replaced a call to `nbd_opt_info()` with a call to > `nbd_aio_opt_info()` and passed in a completion callback which just > calls `exit(EXIT_FAILURE)`. So if the completion callback is called > the test should fail, which it doesn't, at least not on my machine. Isn't that OK? Only .free is required to be called.