On Wed, 2011-10-19 at 12:43 +0100, Roger Pau Monne wrote:
> # HG changeset patch
> # User Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>
> # Date 1319024152 -7200
> # Node ID 5941638b04693f7d8bfa2d6b5563132f54942a28
> # Parent a2a3c4d7333ec15b818b3403f148ad61c254ea82
> libxl: handle the return value of wait_for_dev_destroy select and pass it to
> caller function.
>
> Handle the return value of the select call inside wait_for_dev_destroy
> properly, and return 0 if the device is removed, or 1 if a timeout or error
> happened. Use the return value of wait_for_dev_destroy inside
> libxl__device_remove to properly return from that function.
>
> This patch should be applied after Ian Campbell's v3 "libxl: rationalise
> libxl_device_* APIs".
>
> Signed-off-by: Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>
>
> diff -r a2a3c4d7333e -r 5941638b0469 tools/libxl/libxl_device.c
> --- a/tools/libxl/libxl_device.c Tue Oct 18 13:36:43 2011 +0100
> +++ b/tools/libxl/libxl_device.c Wed Oct 19 13:35:52 2011 +0200
> @@ -367,6 +367,7 @@ int libxl__device_disk_dev_number(const
> return -1;
> }
>
> +/* Returns 0 if a device is removed, 1 if an error or timeout occurred */
> static int wait_for_dev_destroy(libxl__gc *gc, struct timeval *tv)
> {
> libxl_ctx *ctx = libxl__gc_owner(gc);
> @@ -436,7 +449,7 @@ retry_transaction:
> struct timeval tv;
> tv.tv_sec = LIBXL_DESTROY_TIMEOUT;
> tv.tv_usec = 0;
> - (void)wait_for_dev_destroy(gc, &tv);
> + rc = wait_for_dev_destroy(gc, &tv);
> xs_rm(ctx->xsh, XBT_NULL, libxl__device_frontend_path(gc, dev));
> } else {
> rc = 1; /* Caller must wait_for_dev_destroy */
If wait_for_dev_destroy returns 1 (error or timeout) then this will get
returned to the caller, where it means "you must wait". But they will
not be expecting this (because they passed wait==1) and even if they
were having them call wait_for_dev_destroy when it has already timed out
doesn't seem likely.
I think the right thing is for wait_for_dev_destroy to return 0 or an
ERROR_* where one of the ERROR_* can be ERROR_TIMEDOUT and for this to
be propagated to the caller.
The caller in libxl__devices_destroy needs to do something with this
return value as well. It would be good to consume all the watches but
return the first error, or something like that.
Ian.
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