Re: [PATCH] Re: export of sys_call_table

["David S. Miller" <davem@redhat.com>]

   From: "Brian F. G. Bidulock" <bidulock@openss7.org>
   Date: Tue, 8 Oct 2002 16:20:17 -0600

   This version (courtesy of Dave Grothe at GCOM) uses up/down
   semaphore instead of read/write spinlocks.
   
Oh really?

   +static int (*do_putpmsg) (int, void *, void *, int, int) = NULL;
   +static int (*do_getpmsg) (int, void *, void *, int, int) = NULL;
   +
   +static rwlock_t streams_call_lock = RW_LOCK_UNLOCKED;
           ^^^^^^^^
   +
   +long asmlinkage sys_putpmsg(int fd, void *ctlptr, void *datptr, int band, int flags)
   +{
   +	int ret = -ENOSYS;
   +	read_lock(&streams_call_lock);
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   +	if (do_putpmsg)
   +		ret = (*do_putpmsg) (fd, ctlptr, datptr, band, flags);
   +	read_unlock(&streams_call_lock);
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   +	return ret;
   +}