Re: Revisiting DTrace syscall provider

[Paul Goyette <paul%vps1.whooppee.com@localhost>]

On Wed, 25 Feb 2015, Ryota Ozaki wrote:

> On Wed, Feb 25, 2015 at 2:38 PM, Paul Goyette <paul%vps1.whooppee.com@localhost> wrote:
> > On Wed, 25 Feb 2015, Paul Goyette wrote:
> >
> > > modules that provide sys-calls.  Without the module loaded, the syscall
> > > entry point is known no-op; when the module tries to unload, all of its
> > > syscalls are checked, and if any of them points to somewhere NOT THE NOOP,
> > > unload is prevented.
> >
> >
> > Actually, the code checks to see if any those syscalls are currently active
> > for any processes.
> >
> > IIRC, the relevant code is in routine syscall_disestablish() in file
> > src/sys/kern_syscalls.c
>
> Thank you for your suggestions! I'll check them.
>
> BTW, how about using moudle_hold(9) for the refcount?
> Shouldn't we use it for the purpose?

You could use module_hold().  But can you guarantee (for some value of 
guarantee) that module_release() will be called in all cases, including 
errors (ie, unexpected process exit).  :)




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