Re: git: ef6fcc5e2b07 - main - nfsd: Add VNET_SYSUNINIT() macros for vnet cleanup

On Mon, Feb 20, 2023 at 09:12:41PM +0000, Rick Macklem wrote:
R>     nfsd: Add VNET_SYSUNINIT() macros for vnet cleanup
R>     
R>     Commit ed03776ca7f4 enabled the vnet front end macros.
R>     As such, for kernels built with the VIMAGE option will malloc
R>     data and initialize locks on a per-vnet basis, typically
R>     via a VNET_SYSINIT().
R>     
R>     This patch adds VNET_SYSUNINIT() macros to do the frees
R>     of the per-vnet malloc'd data and destroys of per-vnet
R>     locks.  It also removes the mtx_lock/mtx_unlock calls
R>     from nfsrvd_cleancache(), since they are not needed.

In the netinet/netinet6/TCP/UDP we came to a style where we avoid
using IS_DEFAULT_VNET(). Instead doing global and per-vnet init
in the same function:

static globalfoo;
VNET_DEFINE_STATIC(foobar);

static void
foo_vnet_init()
{
	initialize(V_foobar);
	if (IS_DEFAULT_VNET(curvnet))
		initialize(globalfoo);
		
}
VNET_SYSINIT(foo_vnet_init, ....)

We can do a separate init of global state and separate of per-VNET:

static globalfoo;
static void
foo_init()
{
	initialize(globalfoo);
}
SYSINIT(foo_init, ....)

VNET_DEFINE_STATIC(foobar);
static void
foo_vnet_init()
{
        initialize(V_foobar);
}

This allows to:

* guarantee that global state is initialized earlier than per-vnet
* separate all global vars from all vnet vars, and keep them together, easier to maintain
* makes it easier to write VNET_SYSUNINIT() that is complement to VNET_SYSINIT()
* makes it easier to write SYSUNINIT(), if module is unloadable
* sometimes global SYSINIT cab be avoided, if a static initializer is enough

What do you guys think?

-- 
Gleb Smirnoff