Re: SMP question w.r.t. reading kernel variables

2011-04-20 Thread Rick Macklem
On Tue, Apr 19, 2011 at 12:00:29PM +, freebsd-hackers-requ...@freebsd.org wrote: Subject: Re: SMP question w.r.t. reading kernel variables To: Rick Macklem rmack...@uoguelph.ca Cc: freebsd-hackers@freebsd.org Message-ID: 201104181712.14457@freebsd.org [John Baldwin] On

Re: SMP question w.r.t. reading kernel variables

2011-04-20 Thread Alan Cox
On Wed, Apr 20, 2011 at 7:42 AM, Rick Macklem rmack...@uoguelph.ca wrote: On Tue, Apr 19, 2011 at 12:00:29PM +, freebsd-hackers-requ...@freebsd.org wrote: Subject: Re: SMP question w.r.t. reading kernel variables To: Rick Macklem rmack...@uoguelph.ca Cc:

Re: SMP question w.r.t. reading kernel variables

2011-04-20 Thread Rick Macklem
[good stuff snipped for brevity] 1. Set MNTK_UNMOUNTF 2. Acquire a standard FreeBSD mutex m. 3. Update some data structures. 4. Release mutex m. Then, other threads that acquire m after step 4 has occurred will see MNTK_UNMOUNTF as set. But, other threads that beat thread X to step 2

Re: SMP question w.r.t. reading kernel variables

2011-04-20 Thread Rick Macklem
[good stuff snipped for brevity] 1. Set MNTK_UNMOUNTF 2. Acquire a standard FreeBSD mutex m. 3. Update some data structures. 4. Release mutex m. Then, other threads that acquire m after step 4 has occurred will see MNTK_UNMOUNTF as set. But, other threads that beat thread X to