Re: [Qemu-devel] [PATCH for-1.4] migration: restrict scope of incoming fd read handler

[Kevin Wolf]

Am 11.02.2013 17:01, schrieb Stefan Hajnoczi:
> The incoming migration is processed in a coroutine and uses an fd read
> handler to enter the yielded coroutine when data becomes available.
> 
> The read handler was set too broadly, so that spurious coroutine entries
> were be triggered if other coroutine users yielded (like the block
> layer's bdrv_write() function).
> 
> Install the fd read only only when yielding for more data to become
> available.  This prevents spurious coroutine entries which break code
> that assumes only a specific set of places can re-enter the coroutine.
> 
> This patch fixes crashes in block/raw-posix.c that are triggered with
> "migrate -b" when qiov becomes a dangling pointer due to a spurious
> coroutine entry that frees qiov early.
> 
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
> Note: this patch replaces "[PATCH for-1.4 stable] block: handle spurious
> coroutine entries".  It's an alternative fix that I hope Kevin will like more.

Yes, this looks much better to me.

Kevin