Date: Wed, 7 Dec 2016 11:44:49 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Mark Johnston <markj@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r309658 - head/sys/vm Message-ID: <20161207110947.V1119@besplex.bde.org> In-Reply-To: <201612062252.uB6Mqjhr019191@repo.freebsd.org> References: <201612062252.uB6Mqjhr019191@repo.freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, 6 Dec 2016, Mark Johnston wrote: > Log: > Provide dummy sysctls for v_cache_count and v_tcached. > > Some utilities (notably top(1)) exit if any of their input sysctls don't > exist, and the removal of the above-mentioned PG_CACHE-related sysctls > makes it difficult to run such utilities on different versions of the > kernel without recompiling. > > Requested by: bde Thanks. > Modified: head/sys/vm/vm_meter.c > ============================================================================== > --- head/sys/vm/vm_meter.c Tue Dec 6 22:48:28 2016 (r309657) > +++ head/sys/vm/vm_meter.c Tue Dec 6 22:52:45 2016 (r309658) > @@ -314,3 +314,14 @@ VM_STATS_VM(v_forkpages, "VM pages affec > VM_STATS_VM(v_vforkpages, "VM pages affected by vfork()"); > VM_STATS_VM(v_rforkpages, "VM pages affected by rfork()"); > VM_STATS_VM(v_kthreadpages, "VM pages affected by fork() by kernel"); > + > +#ifndef BURN_BRIDGES > +/* > + * Provide compatibility sysctls for the benefit of old utilities which exit > + * with an error if they cannot be found. > + */ > +SYSCTL_UINT(_vm_stats_vm, OID_AUTO, v_cache_count, CTLFLAG_RD, > + (u_int *)NULL, 0, "Dummy for compatibility"); > +SYSCTL_UINT(_vm_stats_vm, OID_AUTO, v_tcached, CTLFLAG_RD, > + (u_int *)NULL, 0, "Dummy for compatibility"); > +#endif I don't like casting NULL, but SYSCTL_* enforces type safety for pointers to variables in a way that breaks normal use of NULL. You are supposed to obfuscate this by spelling the value as SYSCTL_UINT_NULL. This is actually documented in sysctl(9). Bruc
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20161207110947.V1119>